AF447

[Dani]

I have reservations about a flat spin with no forward motion; but with the information publicly available it may be impossible to rule it out.

The theory of a flat spin is completly unfounded. I don't know where this idea started, but I guess it came from Bea's expression "with a high rate vertical acceleration".

Now think just one moment: If you would flat spin a widebody airliner (which I still believe is impossible), what acceleration happens during impact? In the spinning axis of the fuselage, right in the middle, there is nearly zero forward motion and heavy negative vertical acceleration. Perfect for the flat spin theory.

Now change to other parts of the aircraft, e.g. the tail. What acceleration appear there? Because of the rotational speed, there would be heavy decceleration to the side. Which is known to be not happened. Because the vertical stabilizer was found as a whole. It would have simply been clipped of the fuselage.

That's what Bea wanted to tell us: All forces they could assess where vertical decelleration. This happens in a relatively straight flight profile with high sink rate. There was some forward motion, too, I'm sure. But the forward decceleration was way slower and thus didn't deliver marks on the wreckage.

So, please, abandon the spin theory. It's useless.

Dani

[JD-EE]

ttsce - really brief - for Inmarsat satellite frequencies the answer is "some" but not dramatically. The antenna tracking test for Inmarsat-M antennas was suited for a ship in very rough weather that would normally include a deluge. And that's in the same band as the new stuff.

JD-EE

[WhyIsThereAir]

Personally I'll believe almost any scenario that does NOT require the airplane to have gone "straight down" when the problem occurred. I believe this lets out flat spin, and may even let out normal spins and spiral dives.

Why? Because if we believe the ocean current drift data and see where stuff was recovered on the 6th and back-plot it, it ends up about 30nm before the 02:10 ACARS fix. So if the problem happened instantly at 0210, the plane has to turn around in zero distance and cover 30 miles backward. Since it isn't likely it turned around in zero distance and it isn't likely the problem happened exactly at 02:10, the plane probably covered closer to 100+miles horizontally from failure to impact.

Now, let's come up with a failure scenario that starts at 02:13-02:14 or later and ends up 30nm south of the 02:10 fix.

[BOAC]

Now, let's come up with a failure scenario that starts at 02:13-02:14 or later and ends up 30nm south of the 02:10 fix. - err, you mean like maybe they turned back towards the mainland following the 'problem', as previously mooted?

[OleOle]

My point is not to throw a judgment on the position relative to the weather. It is that the a/c was not riding on the airway centerline with the AP in NAV mode straight into the storm, as have been suggested earlier. The pilots almost certainly attempted deviations. I don't pretend this is a big piece of information either.

Looking at the flight path (http://www.bea-fr.org/anglaise/actualite/af447/reconstitued.flight.path.jpg) it seems the 2:10 position is the only one slightly off course. If that was due to systematic inaccuracy of the position records one would assume previous postions to be similarly off track.

Not beeing on centerline at 2:10 could be due to a decision to deviate, but could also be a result of the trouble that began around this time.

[FORDGT40]

Ttcse

"The rotational speed of a large aircraft in a spin or flat spin would be slow. Approximately 3-4 secs per rev?"

Unless my maths have let me down :), with a revolution every 4 seconds, then the tail would have been rotating sideways at circa 100mph - this is a significant speed.

David

[Dani]

ttcse,

Any guesses where the 'torsional' component of separation for the vs came from?

They could come from whatever twisting forces. During an impact, you experience tremendious forces, and the tail is the last one to get them passed on. They could also be in a slight turn.

The report says: "The distortions of the frames showed that they broke during a forward motion with a slight twisting component towards the left."

So, if they are right, the forward motion is bigger than the twisting. That couldn't be the case if in a flat spin.

Anyway, the discussion about spin or not is useless. Because it doesn't deliver a theory about the cause, only about the outcome. We are not interested how they crashed, but why they did (Boac, you remember our discussion in the THY/AMS thread?)

Dani

[WhyIsThereAir]

So if the problem happened instantly at 0210, .

THE problem? Clearly ACARS is saying something is happening at 0210.

Yep, THE problem. Yes, we know that something started to happen around 0210 that looks a lot like pitot icing, but might be something else. But many have asked why pitot icing caused a problem here and it didn't for many other planes.

So I presume that the reports starting at 0210 are indications of Bad Things, but that they are not THE problem, since they don't seem to be sufficient by themselves. I presume THE problem (disorientation, food poisioning, both pilots asleep, pick a reason, whatever) occurred subsequently to the first 0210 report, but maybe before the last 0214 report. This is of course pure supposition - but at this point supposition is all that we have informaiton for.


the plane has to turn around in zero distance and cover 30 miles backward. Since it isn't likely it turned around in zero distance and it isn't likely the problem happened exactly at 02:10, the plane probably covered closer to 100+miles horizontally from failure to impact.

Keep in mind
1)that would be re-entering that cell(indications that particular one reached FL500) they just passed thru (when viewed from above) to go toward the south.

Yes it would. You will note I did not say they voluntarily turned around. I said "X marks the spot" was a spot on their track before the 0210 position. They got there somehow.

2)as they couldn't reach 100 miles in 4 minutes, how would you then explain the termination of messages at 02:14?

Explain? I don't, insufficient data. I can guess lots of things. Maybe they lost electrical. Maybe they crashed at 0214. Maybe something else happened. Keep in mind we don't know where they were at 0214. If the flat spin scenario will get you 'straight down' to the ground in 4 minutes starting at 0210, maybe some other spin will get you 30 miles south of 'straight down'.

While I try to figure out how to do that why don't you work on a solution for landing with mostly a vertical descent onto their belly upon arrival at the backtracked debris zone.

I already did that several posts back. Stall it in nose high at about a 45 degree glideslope. The acceleration vector will be about normal to the "down" direction in the cabin, and the tail hitting first will rip off the VS in the manner the BEA wants it to go.

[sirgawain123]

Could an attitude of 5 degrees nose up and power to CT (AFAIK A330 SOP for innacurate IAS above FL10) help inducing a stall to a heavy A330 at FL37? at certain ISA temps and fast A/C speeds?
B/R

[320 driver]

Dani

So, if they are right, the forward motion is bigger than the twisting. That couldn't be the case if in a flat spin.

Anyway, the discussion about spin or not is useless. Because it doesn't deliver a theory about the cause, only about the outcome. We are not interested how they crashed, but why they did (Boac, you remember our discussion in the THY/AMS thread?)

Dani

You are making statements that are totally unsupported.

What evidence is there that the rotational element in a flat spin is greater than the forward. None at all. You just 'invented' that 'fact'. A flat spin can easily have a fairly modest rotational element if the autorotational forces are small due to a number of factors. Speculation on a rate of rotation is fruitless, it is slower for larger aircraft but we cannot say how slow.

Your repeated assertion that large aircraft cannot flat spin is frankly valueless. You have no evidence to support that. The dynamic forces that create a flat spin in small aircraft can easily be scaled up. Also, several large aircraft have entered spins. If you enter a spin then all that is required to make it a flat spin is longitudinal force (e.g. power).

So 1. Large aircraft can spin. Many have. 2. A spin WILL flatten if you apply longitudinal force.

Therefore it is feasible to flat spin a large aircraft.

I am not saying that this is what happened but it would be foolish to dismiss it.

[Arnold E]

I am amazed that not one of you responded to the obvious, that is, without the wreck and/or the CVR/FDR no one can draw any positive conclusions, everything is spectulation.:confused:

[phil gollin]

To get back to reality.

The nominal life of the data recorders' under-water beacons is up very shortly.

Does anyone know ;

a: Any serious reports of the work being done in searching for the data recorders and their possibilities of success (including depth of water being searched) ?

b: Is the expected life "conservative" and whether it is likely that they will continue to operate (if they are so doing) for a reasonably longer time ?

AND,

I ASSUME, that if they give up the acoustic search for the data recorders that that will be the end of the serious search for the remains of the aircraft ?

Any sensible information gratefully received.

.

[petermcleland]

So are the previous statements about bodies being "unclothed" and all exhibiting "typical flail injuries" normally associated with meeting the high speed airflow of airframe breakup, now being discounted? Surely post mortem examination of bodies is the most precise evidence available in this case. It should be possible to clearly establish whether a body was ejected into a high speed airflow and then fell at terminal velocity till it hit the sea...As opposed to a body that was inside an aircraft that struck the sea.

[iakobos]

ttsce - really brief - for Inmarsat satellite frequencies the answer is "some" but not dramatically. The antenna tracking test for Inmarsat-M antennas was suited for a ship in very rough weather that would normally include a deluge. And that's in the same band as the new stuff
Ships have no or little limitations in terms of space, weight or aeodynamics.
There is no comparison between a 20dB+ parabolic antenna (with tracking) on a ship and an a/c planar omnidirectional antenna.

So they do specifically state which satellite was in use and that basically puts them almost dead center under it. It would take something fairly dramatic for them to lose the satellite. A 30 degree or so change in attitude that was not corrected by the antenna steering logic could do it.
Steering logic ? are you sure Aero-L antennas (L band !) have tracking capabilities ?
Dead center or not does not make a difference, be it 35,800 or 37,000km, same thing.
Point is, the link is not 100% guaranteed, and while L band is a lot less sensitive to precipitations or proximity to the core of a storm than eg. Ku band, it still is not immune.

[320 driver]

My understanding (talking to an avionics development eng) is that the battery life of the FDR and CVR beacons is very conservative. As in most things in aviation, they are built with generous margin to ensure that they meet the specifications in any forseeable circumstances.

[Dani]

320 driver:
What evidence is there that the rotational element in a flat spin is greater than the forward. None at all.

what? Definition of a flat spin is that there is no forward movement at all, while, at the same time, there is a great rotational movement. How do you define flat spin?

Of course, my statements are purely speculative, as are yours, as are all the others. I merely say that there isn't a widebody that ever has spun. Period.

ttcse urged my to deliver examples of other aircraft accidents, but I think it is your turn to show me one single accident where there was a spin. If you have ever tried to stall an airliner (real or in a sim), you see the slugishness, the inertia, that doesn't allow them to spin. It's more like a lazy spiral downwards.

If the aircraft is crippled to a certain extent, that may be different. Bea states that this was most probably not the case. Not crippled in this context is defined by still all important part where attached: fuselage, wing, stabilizers.

Dani

[takata]

320 driver:
My understanding (talking to an avionics development eng) is that the battery life of the FDR and CVR beacons is very conservative. As in most things in aviation, they are built with generous margin to ensure that they meet the specifications in any forseeable circumstances.

Hi,
It was my understanding also until I read lately a paper from the pinger manufacturer. The manufacturer opinion is that the pinger signal is expected to fade very quickly after operating for 30 days. I can't provide the link for it, as I didn't recorded it, but the sense of this statement was very clear: do not expect any signal lasting very long after the designed 30 days. Hence, the accoustic search will stop after 40-45 days because it would be useless to do otherwise.

If the accoustic search is unsuccessfull, the next step would focus on finding the airframe wreckage using adequate means. The BEA first examinations are not ruling out the existence of large pieces of wreckage at the bottom of the Ocean and its a good thing.

The very bad case would have been a shattered field of small wreckage making it almost impossible to precisely locate it but it doesn't fit with the impact clues revealed.

[320 driver]

what? Definition of a flat spin is that there is no forward movement at all, while, at the same time, there is a great rotational movement. How do you define flat spin?

That is NOT a definition of a flat spin. A flat spin is one where the attitude is close to the horizontal plane. Forward motion doesn't enter into it. It is entirely possible to have a flat spin with some forward motion.

Please stop posting comments that extend far beyond your knowledge.

[320 driver]

Dani

Air China span a 747 in a well documented incident off the coast of California.

Dai Davies talks extensively about risk of spinning large gets in 'Handling Tne Big Jets' which is regarded by most as the seminal work on large aircraft handling. If Dai Davies thinks there is enough spin risk to warrant writing about prevention and recovery then I suggest the risk is real.

Or are you prepared to tell us all that you think Dai Davies got it wrong?

[aguadalte]

My question now to the Airbus gurus here is does the airplane allow you to exercise your piloting skills to maximimun advantage in an untrained and or unplanned situation? Remember, I am a Boeing/Douglas guy. Can you pull as hard as may be required? The difference between hitting the ground/ocean and recovery may well be pull hard on the horizion.

I will leave this open for discussion. Obviously the TWA aircraft under Capt. Gibson's command survived a 6 g recovery. The B-727 was never designed for this load factor, and the airframe in question was retired.

I do not want to hear BS about airframe certifiaction standards, comparrison in G loadings, etc. I will supply a link soon to the TWA incident, but I would hope that all professional aviators on this thread are aware.''To answer your question:
Even in ALT LAW 2, Pitch Control is identical to ALT LAW 1 where flight law is a Load Factor demand law, similar to Normal Law, with limited pitch rate feedback and gains, depending on speed configuration.

Low Speed and High Speed Stability is available but with Pitch Attitude Protection Lost.
There is no Bank Angle Protection.
And,
In case of 2 ADR failure, there is No Low Speed Stability;
In case of 3 ADR failure, there is No High Speed Stability.

I therefore would tend to suggest that one could only pull 2,5 G's except if, due to other associated failures, the aircraft would change to Direct Law and Pitch Inputs would be then directly commanded by the pilots.

In other words, only in Direct Law, pilots are allowed to pull more than 2,5 G's...

To answer mine:
IMHO, this means also, that due to High and Low Speed Stabilization (where the aircraft gives inputs to the flight controls to prevent stalling it [and therefore, spin it]) and also to the fact that AoA data is provided to BUSS - Back Up Speed Scale, via the IR part of the ADIRU, in order to enter a stall the aircraft would have to have changed to Direct Law.

FCOM Abnormal Procedures tells us that even in a situation where two IR's or 3 ADR's are lost, Flight Controls Laws would still be ALT LAW 2.
This leads to me thinking that Human Factors may have played a role in the outcome of this accident. Pure speculation I must concede, as most of the argumentation I've seen in this thread.
Easy to accept that, in the middle of the stressing Unreliable Airspeed Indication troubleshooting, the (unprotected/unguarded) IR's were disconnected by mistake (in step of ADR's) in an attempt to display Backup Speed Tape...the rest one can guess. That's much easier, for me, to accept that, than a total failure of aircraft systems, tail fin or brake apart in several pieces.

Ready (and maybe deserving) to be flamed, now...

P.S.- Here's a partial transcript of Airbus Publication: SAFETY FIRST of Dec 2007 written by Joelle Barthe (Flight Operations Engineer, Airbus Industrie)

(my bolding)

In order to decrease the crew workload in case of
unreliable speed, Airbus has developed the Back-
Up Speed Scale (BUSS) that replaces the pitch
and thrust tables. The BUSS is optional on
A320/A330/A340. It is basic on A380, being part
of the ADR Monitoring functions.
This indication is based on angle of attack (AOA)
sensor information, and is therefore not affected
by erroneous pressure measurements.
The BUSS comes with a new ADIRU standard
(among other new system standards), where the
AOA information is provided through the IRs and
not through the ADRs. This enables selecting all
ADRs off without loosing the Stall Warning
Protection.
The AOA information provides a guidance area in
place of the speed scale. When the crew selects
all ADRs OFF, then:
• The Back-Up Speed Scale replaces the PFD
speed scale on both PFDs,
• GPS Altitude replaces the Altitude Scale on both
PFDs.
The Back-Up Speed Scale then enables to fly at
a safe speed, i.e. above stall speed and below
maximum structural speeds, by adjusting thrust
and pitch.

[takata]

It is incredible the amount of imagination caused in people minds by this vertical stabilizer wreckage recovered. One wonder if they are realizing that if the hydraulic system was cripled for whatever reason, and it will be in any case of structural damage implying the rudder, the maintenance computer won't simply address a four minute string of unreliable speed related problems...

On the other hand, when two different materials are assembled together, each one with singularly different resistance and deformation behavior, it is not very hard to understand that a separation will very likely result once a critical level of acceleration is applied.

[Mr Optimistic]

I have tried to search but with 155 pages....

What physical evidence there is, compared to other 'flat spin accidents' pointed out here, seems to show a surprising lack of 'component' as opposed to 'structural' damage (eg the VS separated at the root but little other crumpling, the weak galley structure with right angle joints still intact and pristine trays, the section of wall/bulkhead with jump seats, the control surface with a longtitudinal tear), also no clear (in these views) witness marks of secondary impacts with other translating objects.

Has anyone posted a view of the a/c showing the likely position of the recovered parts on the airframe and were all these recovered in the same general patch of ocean ?

Also worth bearing in mind that the sea wasn't flat: initial impact forces may have been concentrated on certain parts of the structure.

If this has been done over a thousand times here I know what to expect:\

[320 driver]

IMHO, this means also, that due to High and Low Speed Stabilization (where the aircraft gives inputs to the flight controls to prevent stalling it [and therefore, spin it]) and also to the fact that AoA data is provided to BUSS - Back Up Speed tape, via the IR part of the ADIRU, in order to enter a stall the aircraft would have to have changed to Direct Law.


Are you sure the aircraft has to be in Direct Law to stall. My undrestanding of the alt law low speed stabilisation term is that it only introduces a modest nose down term to resist inadvertent stalling but that there was no absolute alpha protection as there is in Normal Law.

[Graybeard]

What law was controlling the flight test A330 when it stalled and crashed?

[augustusjeremy]

and also to the fact that AoA data is provided to BUSS - Back Up Speed tape, via the IR part of the ADIRU, in order to enter a stall the aircraft would have to have changed to Direct Law.Which explains the Qantas incident.

P.S. - Who knows whether they (AF447) went back to normal law or not...

EDITING: The AoA is normally provided by the ADRs - The "BUSS" provides it through IR as a backup. So the doubt remains as to the role of a defective IR in the "standard" AoA output

[Murmur]

Of course not, because airliners don't spin.

Pulkovo Aviation Enterprise Flight 612 - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Pulkovo_Aviation_Enterprise_Flight_612)


Marco

[Graybeard]

It is a spin when one wing is stalled more than the other. The rotation results from the less-stalled wing providing more lift than the other.

A stall occurs when both wings stop flying about equally. Recovery occurs if the cg is ahead of the C/L, center of lift, as the nose will drop, and flying speed is regained.

If the cg is behind the C/L of stalled wings, the nose will not drop, and the plane will not regain flying speed. This is a flat spin. It does not require rotation. As above, for rotation there has to be a partly unstalled wing. Per Wiki, the flat spin angle of attack will be between 65 and 90 degrees, which means there could be some forward speed.

Modern airliners are intentionally flown at aft cg near the safe limit. A load shift will put the cg behind the C/L, and this has happened countless times, usually with cargo.

GB

[VONKLUFFEN]

Big threat... many opinions.. just tell me where is the original preliminary report please.
Thanks

[captplaystation]

Have to agree with petermcleland in the post above, it is absolutely imperative the Brazilians furnish the BEA with the findings of the post mortems or that a further post mortem takes place following the release of the bodies.
There has been enough historical data I am sure to correlate the type of injuries and cause of death with a particular scenario, or at least to help in discounting other theories, which could be invaluable until more concrete data (hopefully) becomes available from further wreckage recovered, or with some chance the recorders.
Any idea why the Brazilian authorities wouldn't make this info available to the BEA as soon as the work had been completed ? , strange indeed :confused:

[Finn47]

Originally posted by Takata

The manufacturer opinion is that the pinger signal is expected to fade very quickly after operating for 30 daysThis is because of the properties of the lithium battery, I think. The nominal voltage stays the same for the specified 30 days and then some, but once the voltage starts to drop, the drop is rather dramatic and therefore the beacon stops sending any acoustic output at some point, rather sooner than later.

Extended battery life would not be too difficult to achieve. Another 200 grams of additional weight perhaps. Peanuts, really.

[aguadalte]

BUSS - Back Up Speed SCALE http://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/thumbs.gif

Right, I already corrected it, thanks.:\

Graybeard:
What law was controlling the flight test A330 when it stalled and crashed?


The aircraft was under Normal Law, but crashed because due to an earlier selection of an altitude of 2000' (if I remember correctly, they had been flying circuits before that Take-Off) the aircraft "grabbed" ALT* mode during a simulated engine failure after V1, and was allowed to stall. (Protections are not active during ALT* transition modes).

[LeandroSecundo]

Hi,

Extended battery life would not be too difficult to achieve. Another 200 grams of additional weight perhaps. Peanuts, really.

http://www.pprune.org/tech-log/379055-cvr-fdr-battery-life.html

Bye.

[Poit]

My apologies for wading in to the discussion a while ago, highlighting similarities in the condition of bodies with previous mid-air accidents.

I've been put in my place by the recent report, and realised that whilst I (like the rest of you) am very concerned and interested in what happened that night, I am not close to the investigation, I am not privvy to all the available information, and as such I really shouldn't have 'waded in' with yet another peice of conjecture.

I was impressed with the honesty and detail of the prelim report, and I now have full confidence that the experts are doing their very best. Let's leave them to do their jobs.

In the mean-time I think we're just going to need some patience.

[BryceM]

I don't know about the status of the search, or about the 'true' battery life of the devices. Other people have commented on these issues. I used to work in the hydrographic survey industry, so I can comment on finding AF447 in the event that the pingers aren't detected.

A quick look on Google Earth at the seafloor in the region of the accident shows that it's pretty rugged. This means that finding the wreckage using the usual methods (sidescan sonar) might be tricky - boulders, cliffs, etc all give shadows which can look like wreckage, or the wreckage return can be hidden in those shadows. If you spent enough money doing surveys in all directions (so that the shadows are cast in different directions in each survey), and were scrupulous about investigating all potential contacts and databasing them ... eventually you would be 99% certain to find it. How long would it take & how much money? Could be 'a long time' and 'a lot'. I don't know the size of the search area, so I couldn't begin to estimate, but certainly tens of millions of dollars, and hundreds if it goes on for very long. You'd need deepwater ROVs to video each contact, and the day rates for the vessels which deploy those are very high (like $250k per day, IIRC).

If the wreckage is largely in one place, which may be the implication of the BEA report, it would seem sensible to continue searching. If it had fragmented in flight, chances of finding specific individual pieces (e.g. FDR, CVR) would be pretty poor. (I mean: you could spend $1bn and not find the CVR & FDR; so you would have to make a judgement up front as to whether it's worth doing the search, based on whether you think the debris field will be localized or scattered over tens of square miles).

I guess some people would have a view on whether it's in the interests of the French gov't to try very hard to find the wreckage. (I don't believe that sort of thing for a second, myself ... maybe I'm just naive).

[TheShadow]

The one very real way in which you can complicate your recovery from a loss of control (spin or whatever) is to have the autopilot surreptitiously auto-trim in as much back-trim as possible. However the pilot doesn't need to organize that, the autopilot will do that all by itself, quite unnoticed by the pilot - as the speed erodes. That pitfall of an autopilot disguised contrary control force is why medium size turboprop airliners are required to be handflown in heavy icing conditions. The phenomenon of autopilot kickout immediately followed by autorotation (i.e. a spin) has been the undoing of many an inattentive crew - after a short period of ice accumulation. We have the recent examples of the DHC8-400 in the US and the Turkish 737 at Amsterdam to emphasize the stealthy suckertrap of auto-trim.

But what was happening to the THS (trimmable horizontal stabilizer) and auto-trim aboard AF447 when the pitot malfunction occurred? Could that pitot icing indication glitch have emulated the icing performance loss scenario? Can the pitot's induced false speed reading predicate the auto-trim's response? Can the auto-trim then be well out of whack nose-up and yet the autopilot still soak up the "stick"-load in order to maintain the stipulated altitude?

If this was in fact (or could've been) the case, what would have happened when autopilot, auto-thrust and (presumably) auto-trim dropped out? How difficult (or improbable) would recovery be if the autopilot kicked out due to it holding greater than a kick-out threshold force of forward elevator?

I imagine a pitch-up into a stall and a wing-drop flick into autorotation would likely be an instant development. Would the pilot, now in manual control and Alternate Law, have any clue as to what was happening? - such that he could correct the out-of-trim configuration and regain control?

Or is it more likely that the combination of unaccustomed manual flight at high altitude, sudden IMC, Alternate Law and roll/pitch/yaw could mask the
back-trim and leave the pilot totally flummoxed?... You only need scant seconds of very nose-low to exceed VNe. And of course we're disregarding here what could have happened to one or both engines thrust during that pitch-up - which may have provided the asymmetry for spin entry.

I've got first hand experience of what happens to a JP5A (Jet Provost) pilot subjected to loads of elevator back-trim when handed over to for spin recovery. They were always non-plussed. The learning experience exceeded the syllabus for spinning but similar to inspin and outspin aileron's effects, it was a worthwhile exercise to file away in instant recall.

in order to enter a stall, the aircraft would had to have changed to Direct Law. Is this statement still operative once the speed input to the ADIRS is wholly corrupted? The aerodynamics of a pitch-up at high altitude would trump that law - methinks.

If the cg is behind the C/L of stalled wings, the nose will not drop, and the plane will not regain flying speed. This is a flat spin. It does not require rotation. As above, for rotation there has to be a partly unstalled wing. Per Wiki, the flat spin angle of attack will be between 65 and 90
degrees, which means there could be some forward speed.

Modern airliners are intentionally flown at aft cg near the safe limit. A load shift will put the cg behind the C/L, and this has happened countless
times, usually with cargo.

More food for thought. Think centrifugal force in a large aircraft spin. Even if it wasn't a flat spin to begin with, anybody/anything loose in the cabin will migrate towards the rear, pushing the CofG even further AFT. Even with baffles, this might also be the case for some of the fuel. Any thrust left on the engines will also tend to flatten the spin. Any heavily back-trimmed aircraft will tend to want to remain in a flat spin, particularly as the thrust increases with height loss (for any given set throttle lever position).
.

[augustusjeremy]

100mph horizontal does surprise me. I would be interested in seeing your math, pm it to me if you don't mind.

A330 length: 58m

radius of spin circle: 29m

circumference: 2piR (pi =~ 3.14etc) =~ 2 * 3.14 * 29 = 182.12 m

182.12/4 (a 'complete' spin each 4s) = 45.53m/s (the tail is running along the path of the circumference)

45.53m/s = 45.53m * 3600/h =~ 164km/h

aprox. 100mph

:ok:

[Will Fraser]

augustusjeremy

4 seconds per rotation = ~175'/sec.

175 feet/sec. = ~10,500'/minute = ~ 115 mph.

115 mph with an axis w/o horizontal velocity.

With horizontal velocity, add for lead, subtract for lag.

The wing tip or tail could have a velocity through air approaching 200mph.

[augustusjeremy]

augustusjeremy

4 seconds per rotation = ~175'/sec.

175 feet/sec. = ~10,500'/minute = ~ 115 mph.

115 mph with an axis w/o horizontal velocity.

With horizontal velocity, add for lead, subtract for lag.

The wing tip or tail could have a velocity through air approaching 200mph.

Yes...

I am not an aerodynamicist but maybe the momentum exerted by the vertical stabilizer in this context in such a large (long) aircraft explains why they're harder to put into a flat spin.

It would depend on the center of rotation/gravity/mass, I believe

[Mr Optimistic]

centrifugal force = speed squared divided by r. So 45*45/30 -ish, getting on for 7g.

[Will Fraser]

Given the pic of the Fuji B707 and B-70, (not that they are representative), rotation in a fully developed flat spin would seem to be almost nonexistent. Any rotation would add asymmetric lift (especially to a swept wing design) and tend to revert the a/c to a conventional spin.

BEA's statement re: flat and nearly vertical impact is sustained by the reasoning that dictates virtually nil or nil rotation.

[JuggleDan]

captplaystation,

Any idea why the Brazilian authorities wouldn't make this info available to the BEA as soon as the work had been completed ?I recall that the official position of the Federal Police of Brasilia, which contradicts BEA's statements, is stated here (http://www.lefigaro.fr/flash-actu/2009/07/02/01011-20090702FILWWW00545-af447autopsie-brasilia-contredit-paris.php) by the AFP:
We have received no official request from the French Embassy or from anyone in France. If there is no demand, it is obvious that they will not receive something they did not ask forMy guess is that the Federal Police of Brasilia expects the BEA to follow some official channels (police SOPs!), and that for some reason the BEA neglects or does not wish to do so.

[Will Fraser]

Which could tend to demonstrate how important to BEA the pathologies are. Being not present at autopsy doesn't preclude including the data thus derived from its report. Rather a blunder and rather transparent? I'm sure it's an oversight and BEA will "append" to its initial report, right?

As important as forensic pathology is, that BEA would pitch a hissy is to me a sign of things to come. Stalling and foot dragging is what I claim here. One could not in any way claim BEA was overzealous. Why not an FAA investigation for Euro mishaps, a BEA for 'western'??

[Belgique]

4 seconds per rotation = ~175'/sec.

175 feet/sec. = ~10,500'/minute = ~ 115 mph.

115 mph with an axis w/o horizontal velocity.

With horizontal velocity, add for lead, subtract for lag.

The wing tip or tail could have a velocity through air approaching 200mph.

The airborne Fin detachment argument for sideways tail velocity in a spin is misbegotten and cannot be sustained.
WHY?
The spinning (or flat spinning] aircraft is in a downward helical flight-path, so everything is relative to that spiral flight-path. The actual sideways velocity relative to the air in that flight-path would be minimal.

The only time that "relative to the world at large" sideways yawing motion would become pertinent to fin detachment would be upon entering the new medium (i.e. the sea).
.

[einhverfr]

100mph horizontal does surprise me. I would be interested in seeing your math, pm it to me if you don't mind.So would I. My quick calculations were 50-70mph horizontal motion for the tail in a flat spin.

Math: The A330 is almost 200ft long, rounded to 200 ft (1 significant digit for quick calculations. This creates a rotational radius of 100ft.

Multiply by pi and we get 314 ft for the spin circumference. This gives us about 55 to 69 miles per hour. Rounding back to one significant digit gives us 50-70 mph.

EDIT: Calculations are wrong. Should be double: 100 through 140mph. Forgot the 2 in 2(pi)(r)

[SandyYoung]

I can't believe that the pinger output is so poor. Instead of sending out lots of weak signals what's clearly needed is a smaller number of really loud signals per hour.

That would have no effect on battery life which is a function of power output and duty cycle. In fact it might extend it. A previous post about 'slower' pings reducing the search area can't be right given that ships travel quite slowly. In any event a very loud ping could be located not be sailing right over it but by triangulation.

Given that most of the planet is covered by water it's likely that planes will come down in it from time to time. Why then are pingers so weak?

[cwatters]

Might be better if it started out rapidly pinging and then slowed down after say a week?

[SaturnV]

whyisthereair and ttcse, takata developed a hypothesis largely based on the wreckage sighted in the several days prior to June 6 that AF447 had deviated right and possibly attempted a return in the direction of the St. Peter and St. Paul rocks.

The Brazilian Air Force's search grids June 2 through 5 were consistent with his hypothesis. These grids were generally east of the track, and once they spotted slicks of oil and other possible wreckage from the plane east of the track, the Air Force concentrated in these areas. However, the BEA report makes no mention of the oil and debris sightings before June 6, and one can now fairly conclude these were determined to be unrelated to AF447 and are discounted.

It was a search grid to the west of the track on June 6 that led to the recovery of the first bodies and wreckage determined to have been from the plane.

A bit after takata posted his hypothesis, there were a series of posts (some by me) with various plots of the surface currents over time, showing direction and speed. These posts were deleted, presumably for straying too far off-topic. In one of the deleted posts, I included the coordinates for where the VS was recovered. I found the coordinates on another site, an unofficial one, and as I recall these were for degree, minute, and perhaps second. (It would take a bit of searching to find them again.)

The plots of the surface current consistently showed, during the first week of June, the drift to be more from west to east, and from south to north, rather than the obverse. The recoveries on the days following June 6 are increasingly north of the recoveries on June 6 and June 7, until by about June 9th or so, nothing is recovered south of the latitude of Tasil.

The inference I drew is that the impact point is almost certainly to the west of where the first bodies were recovered on June 6. How far south of the recovery latitude is conjecture without detailed and accurate data on the current.

Hindsight is always 20/20, but if the Brazilian Air Force had run search grids west of the track on June 2nd, the wreckage might have been found sooner. The grids on June 1 are along the projected track from the reported position at 0210 to Tasil; the two top grids on June 2nd are the grids to the east of the two along-the-track grids of June 1, and a search consistent with the surface current if AF447 had crashed on its track,

http://i136.photobucket.com/albums/q199/tahitiplage/SNAG-0290.jpg

[Graybeard]

For a flat spin to develop, you would expect the cg to be aft of the C/L. The cg was probably 20 feet or more aft of the center of the plane - about where the main gear is attached. The plane rotates about the cg.

Regardless, if a tail fin can't stand 100-140 mph sideward force, how would it hold up in a heavy windstorm on the ground?

This descent no doubt resembled a falling leaf more than a rotational spin.

GB

[Mr Optimistic]

The inertial forces refer to the acceleration necessary to maintain the motion irrespective of atmosphere. The forces necessary to shift air out of the way are additional. However, I am sceptical also, these are huge implied forces. You would need all the inertias and the aero coefficients to do it properly. No doubt someone with the model and the computer will do it. Can't see how it's consistent with the preliminary findings though.

[Graybeard]

"Why then are pingers so weak?"

Before about 1980, airliners had no pingers. Can you imagine how many pingers have been built that were never used at all? Many thousands. There have been only a handful of accidents in the last 30 years where a pinger speeded recovery of the recorders, let alone being crucial to success.

The return on investment in pingers has to be pretty poor.

GB

[Will Fraser]

Graybeard

I'm not sure anyone was trying to connect the VS separation as a result of a spin. If so, I would think it unlikely as well. In fact, the VS separation most likely would have been prior to a spin, if separated at altitude. It is difficult to disagree with BEA re: VS anyway; they have the piece itself, and one hopes they wouldn't have stated the 'result' in the absence of evidence ?
For some,
There seems to be some confusion re: spin and upset. A spin is a final and consistently terminal mode of flight. An upset can include anything prior, in general terms. An a/c, leaving controlled flight, can tumble, break up, slip, skid, invert, tumble again, etc. BEA has no way of knowing, I would submit, what preceded their conclusion of mode at impact. An a/c wants to fly, an upset is not sustainable, the a/c will seek a regime that 'balances' whatever forces act upon it. This is usually a spin, (In the absence of control input) but in general, if most of the surfaces are intact, they work to defeat an imbalanced conservation of the energy it has. When an F-18 departs controlled flight, the pilot lets go of everything. The computer and a/c recover flight on their own. The a/c wants to fly. It takes a lot of work and crossed controls to make an a/c tumble. A spin is not cute, but it is consistent, and stable, in most cases ? Comment?

This brings me to a couple other points. If I were writing the report, a descent as described by BEA would be my decision as well. I am not privy to the information, but it is as benign a result as can be divined, if the purpose is political, and not forensic.

The BEA decry the lack of perfomed autopsy info yet who believes it wasn't made available to them?

In the absence of any (sic) forensic pathology results, they have the audacity to proclaim that the 'bodies were in fairly good shape'.
Excuse me, but in my anatomy class and autopsies at which I was present, I can't remember any one saying as a proper Medical conclusion that John Doe was in 'pretty good shape'. What's the purpose of stating anything that isn't specific and doesn't conform to accepted standards, if not politics?

[Squawk_ident]

mm43

INTOL to TASIL is 364NM and irrespective of the SALPU ORARO intermediate reporting waypoints, the ETA TASIL was 0220z based on M0.82 FL350 OAT 45°C. This gives a GS of 477NM -10KT headwind = 467K

BEA have previously published the auto SATCOM 10 min reports transmitted from departure Rio de Janerio up to and including 0210z. Checking the A/C positions would tend to suggest that there was an easterly component in the headwind and the A/C had drifted nearly 3NM left of track by 0200z. Reference to the MET data published by BEA would also confirm an increasing east component in the wind closer to TASIL.

The wind was from east or north until TASIL max 20kt. AF447 was under autopilot and AT and was perfectly on track and time until until SALPU whatever the wind was.

ATLANTICO requested ETA TASIL from AF447 following the by INTOL SELCAL check (01:35:43). There has been no evidence presented by BEA to suggest that ATLANTICO actually tried to SELCAL the aircraft when not receiving an answer to the requested time at TASIL.
Agreed and here lies the problem. If Atlantico had tried to establish contact either via SELCAL or HF later on, either negative or positive answer would have been mentioned somewhere in the report and it is not the case. We have to admit that -1/ the last attempt by Atlantico to contact 447 was after INTOL at 01 36 14 -2/No ETO TASIL was received by Atlantico.
The requested time for TASIL would suggest that ATLANTICO did not require reports at either SALPU or ORARO - probably due to no known conflicting traffic.

Agree but Atlantico had the ETO given by the crew. Respectively 0148 and 0200 but not TASIL and it was needed to relay the ETO to DAKAR.
From where does 0220 come from? ADS-C may be or estimation by Atlantico from the latest radar reception, but if the position is correct until SALPU (0148 under radar contact and the same given by 447) the ETO ORARO is not respected according to what the ACARS has send as we can see from the published position report.
The speed was reduced at or just after SALPU. Why?
The latest known position indicated in the report is at 02 10 34 by ACARS at N2.98 W30.59, that is to say 71 NM to TASIL and about 10 minutes to go to TASIL at the actual speed. At that time and according to its Mach 0.82 the 447 should have been already at TASIL.

Other than ACARS messages that indicate the SATCOM ANT was still locked to the satellite at 0214z, and the rejected attempts by AF447 to log on to DAKAR ATC, the only other recorded contact with the A/C was the last squawk received at 0148z when approx 250NM from SBFN secondary radar.

Agree. It is consistent with the ETO given by the crew until SALPU estimated at 0148.

[takata]

BryceM - Pinger Life:
Orchestrating a search of this type would not be simple: you're forced to use a bunch of vessels of opportunity, most of whom know nothing about survey techniques, don't have software which allows them to easily plot and run survey lines, may not have survey grade (D)GPS, aren't familiar with the requirements of an acoustic survey, don't have a common means for sharing information, etc. Well-meaning but inept, in all probability. (That's not meant to be offensive - these things are more complicated than they first appear, is all).Actually, it is not the case. The means (vessels and crews) employed are trained for the job and equipment/communications and softwares are not lacking. They already have been used and succesfully recoved orange boxes in the past:

LOUIS DREYFUS ARMATEURS has been working in close cooperation with the BUREAU d'ENQUÊTES et d'ANALYSES (BEA) since Monday 1st June as soon as the accident was announced.
LDA crews and teams have already demonstrated their skills in similar operations with :
- the recovery of the two flight recorders from the Boeing plane that crashed near Sharm El Sheikh in 2004. They were found by more than 1,000 meters depth.
- the recovery of the flight recorder from the Air Moorea plane that crashed in 2007. The black box was found by around 650 meters depth.
Louis Dreyfus Armateurs (http://www.lda.fr/press_release-54.html)

Fairmount Glacier & Fairmount Expedition (reinforced by USN/CG team operating the TPLs):
http://www.lda.fr/img/387_fairmount-003.jpg

And the oceanographic vessel of Genavir (IFREMER/Marine Nationale) "Pourquoi Pas?" which is used as GQG for the operation:
Descriptif du Pourquoi pas ? (http://www.ifremer.fr/flotte/navires/hauturiers/pourquoipas/descriptif.htm)
(its in French but the technical description of the scientific equipment include 950 m² of command posts, laboratories, computer systems (including ultra short waves DGPS system, and so on)
http://wwz.ifremer.fr/var/institut/storage/images/media/institut/airbus_a330/le_navire_oceanographique_pourquoi_pas/369227-1-fre-FR/le_navire_oceanographique_pourquoi_pas.jpg

http://wwz.ifremer.fr/var/institut/storage/images/media/institut/airbus_a330/nautile_et_atalante/369137-1-fre-FR/nautile_et_atalante.jpg

http://wwz.ifremer.fr/var/institut/storage/images/media/institut/airbus_a330/mise_a_l_eau_du_robot_teleopere_victor_6000/369353-1-fre-FR/mise_a_l_eau_du_robot_teleopere_victor_6000.jpg

About the organisation of the search, it is described in the BEA report:

1.16.1 Sea Searches
1.16.1.1 Context of the searches
The estimated area of the accident is over the Atlantic Dorsal Chain. The search is proceeding there in an unfavourable environment due to the depth and to the topography of the seabed. This seabed is little known and presents, over short distances, depths going from 900 metres to approximately 4,600 metres. The distance from dry land implies a lack of radar coverage and radio communication difficulties.
The search area was initially defined based on the airplane’s route and the last position contained in the ACARS messages. This makes an area with a radius of 40 NM, extending over more than 17,000 km2 and located more than 500 NM from the coasts.
The searches on the surface made it possible to locate bodies and airplane parts from 6 June onwards. The position of the floating elements allowed a search zone to be defined based on the work on the currents and the winds. The following figure shows the underwater search area.

http://takata1940.free.fr/images1/search.jpg

1.16.1.2 Principle of the underwater searches
As the aircraft's recorders were each equipped with an underwater locator beacon, it was best to prioritise an acoustic search initially, nevertheless taking into account the limited range of the beacons, which is about two kilometres at most. The propagation of acoustic waves in a liquid medium, which depends on many interdependent parameters such as the salinity and the temperature of the water, must also be taken into account. When an acoustic wave is propagated in the sea, it is subjected to refractions and this generates multiple trajectories. The acoustic waves may also be deflected in such a way that there is a "shadow" region which is never reached by these waves.

Acoustic searches using beacons which transmit at 37.5 KHz (± 1 KHz) are in general more effective than searches using sonar, magnetometers and video cameras. Nevertheless, the duration of the beacon transmission is limited, being certified for a minimum transmission duration of thirty days from immersion. Taking into account the range of the beacons, the hydrophones must be brought closer to the source of transmission, by towing specialized equipment near the seabed. The underwater search devices that are used after localisation of the wreckage must also take into account the depth and uncertainty of the area. In the case of the accident to flight AF447, provision has been made for specialized devices able to descend to a depth of six thousand metres.

1.16.1.3 Resources deployed by France
. By the Ministry of Defence
The French Navy deployed the frigate Ventôse and the Mistral BPC (projection and command ship), which have been taking part in the search and recovery operations for the floating bodies and debris. They have been assisted by their on-board helicopters and Naval Aviation and Air Force planes.
The Emeraude (hunter killer nuclear submarine) was sent to the area to complete the acoustic search system.

. By the BEA
In relation to towed acoustic devices, the BEA approached the US Navy. The latter has two towed pinger locator (TPL) hydrophones and uses them regularly to search for civil or military aircraft crashed at sea.
The US Navy TPLs can operate at up to a depth of six thousand metres. They operate on a waveband between 5 and 60 KHz which includes the frequency transmitted by the underwater locator beacons. The average detection range of the TPLs is estimated at two kilometres at least.

To optimize the use of this equipment, the BEA chartered two available ships from the Dutch subsidiary of Louis-Dreyfus Armateurs. These two tugs are the "Fairmount Expedition" and the "Fairmount Glacier".

The BEA also chartered the oceanographic ship "Pourquoi Pas ?" from IFREMER together with its specialized exploration and intervention resources, the "Nautile" submarine and the “Victor 6000” ROV, which are able to operate at a depth of up to six thousand metres. These vehicles can also map the site of the accident.acoustic search system. The "Pourquoi Pas?" has acoustic detection equipment on board:
• an acoustic Repeater,
• a SMF (multi-beam sonar) modified to operate in passive mode,
• "ROV homer" directional hydrophones, which can be adapted to the underwater intervention resources.

1.16.1.4 Organisation of the underwater searches
Before the tugs and the submarine arrived at the estimated site of the accident, a grid network was made for the search area at the CECLANT centre in Brest by the French Navy and the BEA. The area was thus divided into blocks with sides measuring ten arc-minute lengths (that is to say squares with sides measuring approximately 10 NM at these latitudes, see figure in 1.16.1.1). In most of these blocks, depths can exceed 3,500 m. The working areas were distributed between the surface ships and the underwater resources so that the search was carried out rapidly under good safety conditions.
The tactical coordination of the searches takes place on board of the "Pourquoi Pas?". It is being conducted by the BEA together with the CEPHISMER personnel (French Navy).
The SHOM detachment on board the "Pourquoi pas?" is working to improve the knowledge of the topography of the area. The deep sea multi-beam probe can be used to collect depth data. Current measurement data and data related to the measurement of the speed of sound in the water are also being processed.
In order to use the towed pinger locators, they are towed at approximately three knots as close as possible to the seabed. In order to systematically cover the area, the tugs use lines with a spacing of 2.5 km. This takes into account the scan swath of the TPL which is approximately 2 NM.

[WilyB]

WH

In the absence of any (sic) forensic pathology results, they have the audacity to proclaim that the 'bodies were in fairly good shape'.

BEA states that the 30 bodies (or so) recovered by the French navy were fully clothed and apparently well preserved.

See, no audacity, just facts.


1.13 Medical and Pathological Information

Sailors from the Frigate Ventôse recovered about thirty bodies. A visual examination of the bodies showed that they were clothed and relatively well preserved. All of them were handed over to the Brazilian Navy to be transferred to the Recife morgue.

At this stage of the investigation, the BEA has not yet had access to the autopsy data.

[Will Fraser]

Any description of human remains is contained in an autopsy report. It is presumptuous to report any details unless one is prepared to continue with the proper process. BEA has no business divulging any information relative to the bodies. We disagree. "Apparently well preserved". Please describe in detail what that means in Medical terminology. You see? It is why bodies are wrapped and indexed immediately, so no one will pre ordain. You are mistaken. In my opinion, BEA were pre-empting the Brazilian medicos, trying to establish facts. Why no 'analysis' of the spoiler? the 'trimmable' Horizontal Stabilizer?

[BryceM]

tekata: trouble is, that's 3 ships that are appropriately equipped (by my count), plus some odds and sods (frigates? submarines?) which won't be able to contribute much. Very difficult to make an adequate search of a large area in the small time window with these resources.

Not being argumentative - what looks like a lot of resources isn't, when put in the middle of a large search area.

No offence intended to anyone involved.

[WilyB]

Please describe in detail what that means in Medical terminology. You see?

BEA is just reporting the facts as obvioulsy told by the sailors who picked up the bodies. It means that the bodies were in one piece.

I hit a rabbit once with my car. I stopped the car and picked him up: he was apparently well preserved, but very dead (and delicious with Italian herbs).

[surplus1]

surplus1, in recognizing your conjecture I believe that some of the emphasis and the correlations with previous accidents are misplaced; I covered some of these points in #3014.
Thank you for your reply. I have read and now re-read your posts # 2825 and #3014 carefully.

First let me state that I am not at all married to the idea that AF447 was in a flat spin. I am fairly convinced, due to the BEA report of compression evidence (if accurate) that it was not in a spiral or conventional spin. What I wrote was no more than one hypothesis among many.

I am also not married to the idea that this aircraft fell out of the sky due to some monstrous fly-by-wire system that failed totally causing the aircraft to plunge into the ocean.

Do I have a ‘favorite’ theory? As a matter of fact I do but as yet I have not stated it and do not plan to. You may be assured that it does not include any agendas re: Boeing v Airbus.

I do not actually discount anything, especially not the idea that the aircraft could have been fully stalled with its wings level. In fact I suspect that it was. Since I’m not aware of any stall that would stay that way for so many minutes - other than a stall in a flat spin - that is what made me postulate that possibility. Perhaps I failed to state my views with enough clarity.

But, I confess that I am not an engineer or an engineering test pilot. I’m just a retired line pilot with more than four decades in transport cockpits - enough to readily admit that I do not know everything, never have, never will, and do not have all the answers, or even a majority of them.

Over time I’ve learned a few things about stalls but unfortunately for me that does not include any knowledge of anything known aerodynamically as a “stable stall”. If you would be kind enough to tell me what that is, I would be grateful.

In those four decades of flying the line I’ve never heard of anything known aerodynamically as a “stable stall” to which you referred in all three of your posts. Of course that doesn’t mean that it does not exist, it could well be my ignorance. Again, would you please tell me what a “stable stall” is?

While I do not know factually, I am reasonably certain that the pilots of AF447 were not experimenting with stalls and did not intentionally stall their aircraft. Therefore, if the aircraft did stall on that night – something caused it.

I am extremely confused as to how you could define it by the term “stable” as well as by how that aircraft would be kept in a full stall, of both wings, wings level, over a descent of some 35,000 feet in a [near] vertical trajectory until impact. Please help me to understand what would keep one of the wings from gaining some lift and the other from rolling off during the descent. Something other than ALTN law, please.

If what you’re going to tell me is “ALTN law did it”, then tell me also why, when ALTN law makes the required control input to keep a wing from rolling off, would that not be likely to induce rotation of some type [what we call a flat spin]. What control surface(s) would you expect the computer to move in its effort to keep the wings level?

While some of the correlations with previous accidents, specifically those of the Russian aircraft both of which were TU-154 T-tail machines may be misplaced because they have different stall characteristics; the reason that I and others referenced them is because the stalls resulted from upsets due to turbulence. I think that’s relevant.

As far as I know, stalls are created only by alpha in excess of the critical angle for that airfoil. They can occur at any speed or in any attitude but always for the same reason – excessive AOA.

I’ve never flown the A330 but as far as I know it is equipped with conventional wing and empennage design and control surfaces typical of large transports. While computers normally send signals that actuate and move the control surfaces, FBW, they are not otherwise unconventional as far as I know.

To the best of my knowledge this aircraft is not inherently unstable. Therefore it would not be susceptible to ‘deep stall’ and would not require any unusual control inputs by its fly-by-wire control system. It is not an F-16. It’s just a state of the art transport with nothing unique other that its FBW features. If I am correct, it will behave in stalls just like any other large swept-wing aircraft certified in the transport category. It’s an airplane, not a starship.

Should a stall occur in a level flight attitude, I assume that the pilot will add power and attempt to lower the nose. If the pilot does not deliberately lower the nose, the application of power, due the slung position of the engines, will raise the nose even further, increasing AOA and deepening the stall. Any asymmetry at all in power application will cause a rolling moment. Application of up-aileron – either by a computer or the pilot – to stop the roll will likely induce and flatten the rotation. Since the rudder is limited by ALTN law lockout any effort to use it will be quite limited.

As I understand it, if ALTN law is removed and we go to Direct Law, the aircraft control is like any other. The only difference is that the controls are displaced as the result of an electronic signal to the actuators – rather than cables or rods porting the hydraulic fluids. If that is not correct, I’m more than willing to learn.

The one thing that I do not know is: How does the pilot force the aircraft to go from Alternate Law to Direct Law? Is that possible by a conscious act of the pilot or does the software have to make that decision for the pilot?

A large amount of nose down control input, regardless of who/what applies it, plus the additional power will break the stall but it will also produce excessive high speed very quickly, especially at high altitude. To stop that will take a lot of nose up control – quite likely to produce another high speed stall. While in normal circumstance this should not be completely beyond recovery, with high loss of altitude – does that remain unaffected if the stall was caused by extreme turbulence? If you believe that to be so I can only conclude that you have been fortunate enough to never to have encountered severe turbulence – or for some other reason you consider it to be insignificant. [The differentiation between severe and extreme is intentional on my part.]

It is true that we cannot prove that the aircraft ever entered any type of spin. Neither can we prove that it entered any type of stall. We can’t even prove that it “upset” at any time. We cannot prove that it entered a Cb or two and if it did, we do not know what level of turbulence may have been encountered or its duration. That is all speculation at this point - so take it as such.

We also cannot prove that it impacted the surface intact and right side up. Yes, there is ‘compression’ evidence in some recovered parts – and the BEA theorizes as much. That proves that those parts were compressed – but absolutely nothing else. We also cannot prove that the aircraft descended in a near vertical trajectory – regardless of whether it was right side up, wrong side down, tail down or nose down, or rotating.

Perhaps most important – at this point in time – we cannot prove how or when the VS separated from the aircraft. We only know that it did. The rest is theoretical.

We may all speculate and conjecture ‘till the cows come home but none of us has enough evidence to make a definitive conclusion, and that includes the BEA [unless they are withholding evidence for some reason.]

Aircraft are built and certificated to withstand inadvertent Cb encounters; they do not automatically stall, nor is a spin an automatic consequence of a stall. Large aircraft tend to depart controlled flight relatively gracefully in comparison small aircraft or high performance fighters. The engines do not flame out in Cbs without other contributions, and all aircraft, with their natural stability can transit the relatively short duration of these events in a reasonable stable manner when the controls are used to maintain attitude.


Candidly, I find that statement extraordinary. I do not subscribe to the idea that airliners are “built to withstand inadvertent Cb encounters”. I sincerely hope you do not plan to penetrate Cbs based on that premise. Airliners are built and certificated to withstand very specific positive and negative “g” forces. That is all. There design ‘strength’ is tested by computer modeling and on the ground. They are not intentionally flown into Cbs during flight testing. They all have specific certified ‘limits’ applicable to civil transports.

It is true that airliners do not automatically stall; it is also true that a spin is not the automatic consequence of a stall.

Whether or not transports depart controlled flight relatively gracefully or not is open to depate. What is not open to depate is that large transports do stall; large transports do depart controlled flight; large transports can exceed their certification limits. A substantial number of the pilots present at the time of departure from controlled flight are no longer available to give us their opinions.

Many transports have be lost due to stalls from which they did not recover. Many others have been lost due to encounters with Cbs. Many have exceeded their certification limits in turbulence and dives resulting from upsets; recoverd FDRs have confirmed the ‘g’ levels at which they experienced structural failure. Engines have been known to flame out as a result of turbulence – they have also been torn from their mounts in the process. Many transport airframes have been torn apart by extreme turbulence encountered in Cbs and also in clear air.

Jet engines have experienced compressor stalls and flameouts as a result of heavy turbulence. That is a matter of record. I don’t see how you could imply that it is impossible.

With all due respect, to believe that this “can’t happen” is not conducive to old age. Your postulation is a dangerous one, sir.

I readily admit that we do not know if AF447 penetrated a Cb or if it experienced severe or extreme turbulence. All that we know is that potentially severe weather existed in the area it was crossing on the night of the accident.

I offer this third party statement for your consideration:
"Current state-of-the-art in aircraft modeling cannot accurately predict aerodynamic and/or flight dynamic characteristics under departed and loss-of-control conditions." – Source: NASA, Aeronautics Research, Aviation Safety Program, IRAC (Integrated Resilient Aircraft Control, 2007)


IMHO your analytical logic fails with the assumption that the pitot systems would see different air masses on each side of the aircraft. From experience of tests and often due to the architecture of the pitot systems (cross balance pipes) this occurrence is most unlikely.

Sorry, we disagree. First of all there are no “cross balance pipes” between pitot systems. They are independent of each other. Cross balance is between static ports, not pitot tubes. Secondly, severe turbulence can disrupt airflow to pitot probes – both in updrafts and down drafts. Whether or not that will produce erroneous airspeeds and warnings will depend on the duration and intensity of the up/down drafts and the time delays built into the warning systems. I do not know what compensations may be built into the A330 systems for this purpose, if any.

Indeed there are many IF’s. Some of us are determined to associate the ACARS messages with the cause of the accident. Others believe there may be different reasons that triggered those messages after the upset was fete acompli (sp).

None of us will know what happened until the FDR and CVR have been recovered and analyzed. If in the absence of the recorders the Board still chooses to make a probable cause determination, for many of us, including me, the actual cause will remain unknown.

[takata]

BryceM:
tekata: trouble is, that's 3 ships that are appropriately equipped (by my count), plus some odds and sods (frigates? submarines?) which won't be able to contribute much. Very difficult to make an adequate search of a large area in the small time window with these resources.

Ok, but now, it is a completely different point from your previous one "Well meaning-but inept, in all probability" without having a single clue for saying that, arguing that an ad-hoc "opportunity fleet" was doing a job which should be left to the "pros".

Actually, this is a serious effort if one consider the location of the disaster which is fairly remote from Europe/USA. Having four dedicated vessels (the Navy SNA is a pretty good asset added to the detection party and a second one (US or UK) has probably already reinforced the fleet), all including specialized crews trained for the task with all the adequate equipment deployed here in less than 10 days could not have been possible without an immediate and effective planning following the crash-day.

Adding more non dedicated ressources wouldn't be the good choice, as you wisely pointed it previously, but there is not scores of specialized means, considering that the mission could last several months and that a relieve would be needed at some point.

[SandyYoung]

Graybeard,

You said "The return on investment in pingers has to be pretty poor".

How does one calculate that? If this pinger is not heard and it's required to use conventional methods to locate the CVR etc. the cost of that will likely be massive.

And if, heaven forbid, another Airbus is lost because we don't manage to learn the lessons of this loss the cost of that, both in human life and the plane, will outweigh a great many pingers.

Reading the posts here it's clear that far more information is needed. That can only come from retrieving the instruments. In any case can anyone tell us why we don't just have a massive 'ping' every hour? The listening gear on all Navy ships, especially submarines, is very sophisticated and would detect that, on a sensible sound frequency, very quickly.

Or have I missed something?

[Mad (Flt) Scientist]

.....

Over time I’ve learned a few things about stalls but unfortunately for me that does not include any knowledge of anything known aerodynamically as a “stable stall”. If you would be kind enough to tell me what that is, I would be grateful.

In those four decades of flying the line I’ve never heard of anything known aerodynamically as a “stable stall” to which you referred in all three of your posts. Of course that doesn’t mean that it does not exist, it could well be my ignorance. Again, would you please tell me what a “stable stall” is?

.....

I am extremely confused as to how you could define it by the term “stable” as well as by how that aircraft would be kept in a full stall, of both wings, wings level, over a descent of some 35,000 feet in a [near] vertical trajectory until impact. Please help me to understand what would keep one of the wings from gaining some lift and the other from rolling off during the descent. Something other than ALTN law, please.

If what you’re going to tell me is “ALTN law did it”, then tell me also why, when ALTN law makes the required control input to keep a wing from rolling off, would that not be likely to induce rotation of some type [what we call a flat spin]. What control surface(s) would you expect the computer to move in its effort to keep the wings level?

.....

If I may be so bold as to attempt to answer these points.

An aircraft can be in a "stable stall" if it possesses adequate elevator power to hold the AOA above the critical value, retains enough roll control authority to allow the crew to maintain wings level, retains enough directional stability and/or rudder power to keep sideslip relatively constrained and, in such circustances, if the crew elects to remain in the flight condition. (I'm excluding a "locked-in" stalled condition, such as a T-tail deep stall, where the crew may not have the option, at least in the pitch axis).

Without specific knowledge of A330 high-AOA aerodynamics, and just looking at the configuration, with a low set tailplane I would expect there to be plenty of elevator power - both to pitch down if desired, but also to stay post-stall as well. Assuming AB tried to get reasonable handling characteristics for the natural stall (always a good thing to do, aerodynamically, whatever "protections" you plan on building in) then there may well be a inboard/midwing stall - perhaps from the pylon/wing area? - which would imply that some (outboard) roll control should still exist.

The question then becomes, why would the crew not recover, since I believe that the configuration shouldn't be vulnerable to the locked-in case. The answer might lie in the nature of the upset and the pitch/power unreliable airspeed procedure.

Speculation: once in the post stall regime, with a high AOA, a pitch attitude near the horizon (as the procedure calls for) might not have been enough to reduce the AOA if the flight path had dropped 30 degrees or more below the horizon. Similarly, the intermediate power (I believe) called for might not have been enough for the very high drag of the developed stall. In that scenario the crew actions of flying pitch and power and maintaining wings level could, conceivably, lead to a long, stable, stalled condition with a near-zero pitch attitude, a relatively high rate of descent and a fairly low forward speed.

In the context of that speculation I'll note that fixed pitch, apply power, is the typical low altitude "recovery from stall warning" FAA training but does absolutely nothing for you at high altitudes, where you don't have the power to just drive out of the stall and need to lower the nose. The unreliable airspeed procedure is more designed to maintain you in a stable flight condition and avoid an upset, not necssarily to provide recovery from an upset once it develops.

[JD-EE]

Will Fraser, I suspect the news media should do a little explanation to their readers that the BEA reports "pretty good condition" is probably a declaration of a crewman on the vessel that picked it up with perhaps a remark or two from the medic. Broken bones but basically all in one piece is pretty good condition for somebody used to people coming apart and bleeding heavily.

edit - besides, as noted, they said "relatively well preserved" not "pretty good condition". That moots most of my comment just above.

I am beginning to wonder if the BEA formally asked to view the autopsies. I get the impression that the Brazilians are sticklers for procedure. The French may have asked informally relying on their formal status and been "rightly" rebuffed by the Brazilians. A formal request might have turned the trick.

edit- Another issue that I personally have with the report is that it's formally organized and reasonably complete but appears to be "sloppy" with critical informational clues, such as SatCom antenna and satellite used tossed in as after-thoughts. The particular SatCom transceiver used might shed more light on the ACARS communication pattern.

Upon rumination I've concluded that 1 month is a nice time limit for a plane that has faced a deadly mishap under conditions that allow its quick location and recovery of parts. The BEA could have been under such time constraints to meet the 1 month deadline that they didn't have the time needed to tighten up the report with more details on silly things that would not normally affect an investigation. -/edit

I'm willing to see this as a misunderstanding created by cultural differences.
Differences between the legal systems of the two countries involved could have added to the issue.

This is simpler than a growing conspiracy in an internet savvy world. If there is a conspiracy people like the pilots here, the engineers here, the experienced investigators here, and other specialists here would dig out the truth from almost anything they concoct to protect their backsides.

JD-EE

[JD-EE]

Squawk_ident (http://www.pprune.org/members/25961-squawk_ident) (and others)

You folks into the no proof of somebody alive from 0135 or so onwards please consider page 34 paragraph 1.16.2.1 and let me and others know of the plane itself might have tried to initiate contact with Dakar or the pilots had to interact with the equipment to make it happen.

JD-EE

[takata]

JD-EE:
Will Fraser, I suspect the news media should do a little explanation to their readers that the BEA reports "pretty good condition" is probably a declaration of a crewman on the vessel that picked it up with perhaps a remark or two from the medic. Broken bones but basically all in one piece is pretty good condition for somebody used to people coming apart and bleeding heavily.Well... about 30 out of 51 bodies were recovered by the French Navy. Most were transfered from Ventôse to BPC Mistral which is fully equiped and teamed for a very serious examinations of the "body state". Look here:
Mistral Class ? Amphibious Assault, Command and Force Projection Ship - Naval Technology (http://www.naval-technology.com/projects/mistral/)
[...]
The 69-bed, 750m² hospital is equipped with two operating theatres. If additional hospital or medevac space is required, the hangar can also be converted into a modular field hospital.

I would consider as a fact that the BEA forensic team (barred by the Federal Police) would be fully informed of any "medical observations" made by the French Navy hospital team, no matter if the Brazilian are still dragging their feet and do not fully cooperate with them.

The Brazilian Federal Police is in charge of the victims identification in cooperation with Interpol (including the French police team which is not allowed to do anything). They stated that this task was their primary one and a report would follow once the identification work will be completed. They don't want the BEA killing the suspense by revealing too much about it.

But anyway, I would consider that if the BEA mentioned this observation, it should be taken as a fact backed by a serious medical advice.

[mm43]

Squawk_ident

INTOL to TASIL is 364NM and irrespective of the SALPU ORARO intermediate reporting waypoints, the ETA TASIL was 0220z based on M0.82 FL350 OAT 45C. This gives a GS of 477KT -10KT headwind = 467KTThe distance above hasn't been taken from the sector distances on the Enroute Chart, but is the calculated distance. The distance from INTOL to the 'derniére position connue' - last known position at 0210z is 293NM, and equates to an average GS of 475KT which puts the A/C about 1 minute ahead of estimate, based on the above quote.

EDIT:-
My apologies, I now realize you are raising your question based on the 0133z position report with ETO SALPU 0148 and ETO ORARO 0200z.

No wonder ATLANTICO were requesting an ETA for TASIL! They had already checked AF447 on 6649 and if they couldn't raise them you'd think they'd have tried the secondary HF frequency of 5565.

Going back to the HF frequencies, at 00:36:40 RECIFE CENTER on VHF had already told AF447 to contact ATLANTICO on PRI 6535 SEC 5565 at INTOL. This was later retracted at 01:31:44 when RECIFE CENTER changed the HF frequencies to 6649 /5565 at INTOL and 6535 at TASIL. Once again there seems to have been confusion.

BEA do not appear to have made a comment regarding this discrepancy - it being politic not to say anything pointing the finger in the Preliminary Report.

I suspect the Captain was already taking his rest period when the transfer from RECIFE CENTER to ATLANTICO took place. END EDIT

Agree but Atlantico had the ETO given by the crew. Respectively 0148 and 0200 but not TASIL and it was needed to relay the ETO to DAKAR.
From where does 0220 come from? ADS-C may be or estimation by Atlantico from the latest radar reception, but if the position is correct until SALPU (0148 under radar contact and the same given by 447) the ETO ORARO is not respected according to what the ACARS has send as we can see from the published position report.
The speed was reduced at or just after SALPU. Why?ATLANTICO ~ DAKAR audio with the TASIL time of 0220z is on this tape:-

http://countjustonce.com/af447/audio_020709.mp3

But how ATLANTICO derived the time is another matter.

mm43

[safetypee]

surplus1, thanks for your views and the comprehensive explanation. (#3133)

First the stall: my hypothesis is that with the loss of airspeed procedure the aircraft was likely to slow down (power, attitude), which in the circumstances of weight and altitude would progress towards the stall.

Modern swept wing aircraft, in general, tend to pitch up into the stall (usually gently) – I don’t know if the A330 does this. If the nose-up pitching moment remains at post stall AOAs then without any nose down elevator the stall may be described as ‘stable’ (not the best of terms, as the condition may involve pitch and/or roll oscillations). Like a stall with full back stick, the wings may rock, but some lateral stability usually remains – why should the wings ‘roll off’.

My understanding is that in ALTN law (no speed protection) a stall is possible – AOA protection may be available, but I await an answer to my previous questions on this.
It is also my understanding that the normal control law in manual flight provides a ‘follow up’ trim function – at least with the stick free the system holds attitude. If ALTN law is the same/similar, then the aircraft may be trimmed into the stall, or at least at a very slow speed before the stall. The alternative is to use manual trim.
Without trim stick-force feedback the crew might be unaware of the trimmed state, they would have to look at the trim indicator – I have asked validating questions on this elsewhere; note similarities with conventional auto trim (also covered by TheShaddow), but the A330 systems appears not have the same mechanism as conventional auto trim, which disengages with the autopilot disconnect.

The slow speed trimmed state, together with any nose-up pitching moment could maintain the stalled condition (stable stall), which the crew may not deduce, and even with full nose down control input (not an instability), the situation is not recoverable without applying nose down trim: c.f. 737 AMS acct & UK incident. A conventional aircraft has stick force proportional to displacement from trim, whereas ALTN appears only to have to have force proportional to stick position – validation required please.

The important issues are; as stated by TheShaddow (#3106)… “But what was happening to the THS (trimmable horizontal stabilizer)” and “…. mask the back-trim and leave the pilot totally flummoxed?”; our difference is that as explained above, the nose remains high in a stalled condition.

Re turbulence: in general terms, the certification requirements require that an aircraft can withstand the ‘worst case’ gust (turbulence) from both aerodynamic and structural perspectives when flying at Vra; at slower speeds, a stall (or roll upset) is possible. Engines have similar requirements, but also like aeros/structues not necessarily considering all contributing issues. Furthermore, “what is worst case” and how is it affected by crew action; the industry still has to learn, unfortunate from accidents like those you cite.

Our views don’t differ on Cb encounters, my “inadvertent” is in the context of not premeditated or not deliberate.

Re pitot balance; I have corrected my post, and in other replies explained that the point is still relevant. Turbulence is most unlikely to cause the abnormalities reported – consider that a gust is more likely ‘alpha’ opposed to IAS change.

MFS #3136, thanks for the parallel view. In addition to your post-stall description I would appreciate comment on the trim issues.

[JD-EE]

safetypee,

I'm not a pilot and don't pretend to be one. I know commincations. That's simply where I come from.

Your description of the deep stall and coming out of it is reasonably clear. I'll add that my understanding of any stall is that you get buffeting. I further understand the aircraft had its CG shifted aft by some amount. (It sounds large to me, but what do I know?)

They were apparently or at least possibly flying into a really nasty set of conditions. Their 0210 position seems to plot to inside the West edge of the most severe of the conditions, if I am interpreting the temperature contours as being of interest relative to the severity of conditions.

Entering that region may have upset the applecart leading to a stall that, due to buffeting from the "rough air" (as pilots often say in announcements to the passengers), they were unable to notice. The arrived, somehow, at a condition that required mitigation by precisely the opposite of what they were doing. This persisted, due to no horizon reference, until they bottomed out of the clouds and got low enough the rain did not obscure vision. At that time recovery would be impossible.

Doesn't recovery with a pilot flying the plane require that the pilot actually be aware that the plane is in a stall condition? How possible is it that the poor fellows simply were not aware of the plane's true flight configuration until too late?

JD-EE trying to learn something that MIGHT explain the plane coming in relatively flat quite close to their last reported position if not behind it.

[Tailspin Turtle]

If the pilots lost attitude reference or couldn't reconcile which one to use, the default maneuver in instrument conditions is a spiral dive even if the loss of control began with a stall. A spiral dive will get the airplane from 35,000 feet to the water in less than a minute. The airplane won't come apart even if it goes supersonic if the computer is restricting load factor. If that's in fact what they got into, they could still hit wings level and flat at a high rate of sink if they finally got attitude reference back but too late to completely pull out.

[galaxy flyer]

MfS

We now practice high altitude (FL 430) stall recoveries. It is amazing, with a slow degradation of speed into the shaker, how long and how much altitude is required to regain M.75, the min to start pulling. Basically, 5-10 degrees nose down at MCT thrust and 4000-5000 feet, IIRC.

GF

[einhverfr]

How would the A330 react to a negative G stall?

[Hyperveloce]

Just read it. frustrating. no forensic data available to the BEA at the date of the report ? just visual inspection made on 30 bodies on board the Ventose frigate. In the absence of the recorded data of the flight, forensic data and associated identities when available seems of prime importance. Analysis on the debris would indicate that the structural integrity of the aircraft was not compromised before it impacted the sea surface with a high vertical speed (a high rate vertical *acceleration* is mentionned in the report). The VS would have been detached with a forward motion by the impact, but the damages on the lower part of the rudder does not seem adressed: did the aircraft impact the surface tail first, then belly ? It is said that the connecting brackets between the floor and the walls were bent backwards: is it the result of the impact with a high vertical speed and tail first/a positive pich ? does it suggest that the aircraft had also a significant horizontal speed ?
No analysis of the distribution of the debris versus their drift/date of recoverage. If the aircraft impacted the surface in one piece, the debris/bodies were initially collocated: between the debris collected on June 6 and those collected on June 9, there is a differential drift between groups of debris/bodies (approx. 15 NM on 6 days for the ones, approx 60 NM on 9 days for the others) which is very difficult to account with the NOAA data derived from satellite observations. Furthermore, if the AF 447 had been flying at mach 0.82 from the last ACARS position at 22:10Z, to 22:14:30Z the aircraft would be too much north on its way to TASIL to explain the position of the first debris collected on June 6 (it would require a drift toward the west).
About the ACARS temporary interruption at 22:13Z, a minute before the definitive interruption: no explanation offered (severe met conditions degradating the satcom link budget ? unusual aircraft attitude and possible fuselage masking ?).
It is a report a bit frustrating because about established facts only, giving the feeling that sometimes it would require a bit of interpretation or explanation (of the established facts) or even expert assumptions/opinions about possible causes. I have learnt more by reading the contributions of the good, experiented flying people here on PPruNe than by reading this report, despite less data available to them.And the main question remains unanswered: how did the pilots come to lose the control of an Airbus which is said to be fully controlable even in alternate law 2 and pich & thrust, moderate turbulences, and procedures (unreliable speed) to implement.
How the crew reacted to the cascade of fault reports, alarms and applied the procedures is surely part of the key. Stall or overspeed warnings are not recorded by the ACARS but if the crew were subjected to stall alarms whil flying in ALTN 2/pich & thrust, and instructed by the procedures to take them in account: how should they have reacted to these stall alerts ? (the Air Caraibe captain chose to ignore them despite th instructions). Would they alter the pich & thrust parameters on their own (decrease pich and/or augment thrust) to gain speed ?
Sorry for this long contribution.
Jeff

[Mad (Flt) Scientist]

It seems to me a standard stall from flight-levels to the sea is unlikely. Either the crew would recover or the natural stability of the aircraft wouldn't allow it to be sustained.

That presumes that the crew would be aware of the stalled condition. With no reliable or trusted airspeed information, and with perhaps serious doubt in the crews' minds as to the validity of altitude data also, and thus perhaps no indication of the actual flight path, I'm not sure we can assume that a stall would be easily identified from the available data.

Only a deep-stall would be a stable stall.

I disagree. Deep stalls are a form of stall where the aircraft cannot be recovered to normnal angles-of-attack by means of the aerodynamic controls, due to (typically) blanking of the empennage.

Stability merely requires that there be a combination of angle of attack and flight controls which will maintain the post-stall condition. Any aircraft with a post-natural-stall stick pusher system has to be capable of a stable stalled state if the crew so elects. Such aircraft are not, in that state, deep-stalled, because they are recoverable. (NB The A330 is not such an aircraft in terms of architecture, simply pointing out that stability /= deep stall)

[Mad (Flt) Scientist]

MFS
As for crew hindering recovery, I am a believer that all pilots can make mistakes dealing with critical urgent situations.

Otherwise, you disagreed to my "only a deep-stall would be a stable stall" but in talking it out appeared to discount it for the A330. And I am trying to be specific to the A330 and not talk for all aircraft in general.

No, I wasn't discounting the possibility of being able to control the A330 in a post stall regime - what I was pointing out that there are definite counter examples that prove that not all stable stalls are deep stalls. Therefore there exists the possibility that such is also the case for the A330. Basically deep is not the same thing as stable. What I was illustrating is that if you have enough pitch control power you can hold an aircraft at an AOA above the stall, without it being deep stalled.

If the cg was towards the aft end of the range then it's definitely possible, in my mind, that there was enough control authority in the pitch axis to hold the aircraft in the stalled condition. Depending in detail on what the (natural) stall characteristics of the aircraft are like of course - if it's a root stall I'd expect a fairly large pitch down that might not be controllable. But if it's mid wing, then it might have a post-stall solution. If its a tip stall then there'd be a pitch up, but in that case I'd expect the roll axis to be a handful which would preclude stability in that axis in all likelihood.

[ClippedCub]

Any aircraft with a post-natural-stall stick pusher system has to be capable of a stable stalled state if the crew so elects.Stick pushers aren't designed for post stall, but an accelerated stall can preclude stick pusher activation. They are intended to prevent stall. The A330 configuration won't exhibit a 'stable', or deep stall characteristic, ccrew desire or not. It will buck and roll and yaw when stalled and will not find a naturally stable position in the baseline configuration unless there is a spin element, i.e., normal or flat.

It could have been bucking all the way down, or the aft cg, and/or, reconfiguration of slinging engines and/or breaching fuel baffles could have set it up for a flat spin. The tail in this case wouldn't be enough to overcome the stalled condition. A normal spin would have imparted too much energy into the airframe on impact.

Somebody mentioned the spoiler removal as perhaps reverse flow when extended, either in the air, or somehow the airplane was traveling backwards on water entry. Another explanation would be retracted spoiler would have been ripped off by the hydraulic shock of a high AOA impact.

As an example of a similar configuration in stall, take Flight 903, an A300,

DCA97MA049 (http://ntsb.gov/ntsb/brief.asp?ev_id=20001208X07893&key=1)

NTSB Identification: DCA97MA049 .
The docket is stored in the Docket Management System (DMS). Please contact Records Management Division (http://www.ntsb.gov/info/sources.htm#pib)
Scheduled 14 CFR operation of AMERICAN AIRLINES
Accident occurred Monday, May 12, 1997 in WEST PALM BEACH, FL
Probable Cause Approval Date: 2/11/2000
Aircraft: Airbus Industrie A300B4-605R, registration: N90070
Injuries: 1 Serious, 1 Minor, 163 Uninjured.The flight was assigned an airspeed of 230 knots and cleared to descend from FL240 to 16,000 feet in preparation for landing at Miami. The FDR indicated that while the autopilot was engaged in the descent, the power levers moved from the mechanical autothrottle limit of 44 degrees to the manual limit of 37 degrees. As the aircraft leveled at 16,000 feet the airspeed decreased. The F/O began a right turn to enter a holding pattern and added some power, which stabilized the airspeed at 178 knots. However, the right bank and the resultant angle of attack (AOA) continued to increase, despite left aileron input by the autopilot. As the autopilot reached the maximum input of 20 degrees, bank angle increased past 50 degrees, and the AOA increased rapidly from 7 degrees to 12 degrees. At this point the stick shaker activated, the autopilot independently disconnected, the power was increased, and full left rudder was used to arrest the roll. The bank angle reached 56 degrees, and the AOA reached 13.7 degrees at 177 knots. The aircraft then pitched down, and entered a series of pitch, yaw, and roll maneuvers as the flight controls went through a period of oscillations for about 34 seconds. The maneuvers finally dampened and the crew recovered at approximately 13,000 feet. One passenger was seriously injured and one flight attendant received minor injuries during the upset. According to wind tunnel and flight test data the A300 engineering simulator should adequately represent the aircraft up to 9 degrees AOA. Unlike the accident aircraft; however, the simulator recovered to wings level promptly when the lateral control inputs recorded by the FDR were used. The roll disagreement between the simulator and accident aircraft began at 7 degrees AOA, and it appears that some effect not modeled in the simulator produced the roll discrepancy. Just prior to the upset the accident aircraft entered a cloud deck. The winds were approximately 240 degrees, 35 knots, and the ambient air temperature was approximately minus 4 degrees C. An atmospheric disturbance or asymmetric ice contamination were two possible explanations considered, but unproven.
The National Transportation Safety Board determines the probable cause(s) of this accident as follows:
The flightcrew's failure to maintain adequate airspeed during leveloff which led to an inadvertent stall, and their subsequent failure to use proper stall recovery techniques. A factor contributing to the accident was the flightcrew's failure to properly use the autothrottle.

Don't be surprised by the sym not matching the flight trace. This is a non-linear flow regime and the wind tunnel data would be all but useless when extrapolating full scale Reynolds numbers, and the flight test data would be limited, and taken in controlled conditions.

[Mad (Flt) Scientist]

Stick pushers aren't designed for post stall, but an accelerated stall can preclude stick pusher activation. They are intended to prevent stall.
Not true for all aircraft. On some types they are used either to provide stall identification and/or to prevent excursions to high AOA where a deep stall IS a concern, but they are set to fire post CLmax (i.e. with the wing stalled) in the interest of maximizing aerodynamic performance. But as the A330 doesn't have them anyway thats tangential.

The A330 configuration won't exhibit a 'stable', or deep stall characteristic, ccrew desire or not. It will buck and roll and yaw when stalled and will not find a naturally stable position in the baseline configuration unless there is a spin element, i.e., normal or flat.

That really depends on the details of the stall location and progression. I can conceive of it doing as you say; I can also conceive of it being relatively stable/controllable. It all depends where the wing stalls, how much of it stalls, and how sensitive it is to AOA shifts in terms of progression.

[ClippedCub]

I can also conceive of it being relatively stable/controllable.The stick pusher can be post stall for accelerated stalls. The evidence, and experience points to sustained stalls on conventional airplanes being an unstable event unless stabilized by gyroscopic forces.

[RatherBeFlying]

Re turbulence: in general terms, the certification requirements require that an aircraft can withstand the ‘worst case’ gust (turbulence) from both aerodynamic and structural perspectives when flying at Vra; at slower speeds, a stall (or roll upset) is possible.I would add that the 'worst case' gust is a certification standard that nature can and does exceed at times, perhaps at the 10^^-9 frequency.

[philipat]

surplus1:


Perhaps most important – at this point in time – we cannot prove how or when the VS separated from the aircraft. We only know that it did. The rest is theoretical.




I thought we also knew from the BEA that the VS was ripped off FROM AFT. I thought I also read that one of the spoilers had been ripped away by forces in the wrong direction, but maybe I'm wrong. This begged the question of how the aircraft could, apparently, have entered the water tail first and hence my earlier question about whether this was consistent with a spin or flat spin. I guess an attendent question would be how else the VS could be torn away from AFT?

Again, I am just trying to learn and these are questions directed to the better informed herein. I stand more than prepared to be corrected on any of these observations and mean no disrespect if my comments appear to be contradictory in any way.

[ClippedCub]

My theory is the after body was ripped away from the VS on impact, not the other way around. Either that or the horizontal separated downward in flight ripping the after body away from the vertical. The spoiler was ripped forward if extended, or upwards if retracted. A belly flop would be consistent with a stowed spoiler.

[ClippedCub]

Regarding that damaged spoiler. It could've been due to secondary flow of water after impact rather than initial flow. If at impact water was pushed away from under the wing there would then be a reversal toward the wing. Also possibly a wave might've done that. The spoiler was made to take forces from the front, who knows what it was or wasn't capable from the rear. Significant strength from backside forces probably not a requirement.

Would have to take exception to that, built pretty tough from the pictures and the design condition. Wouldn't be much weaker in the deployed, reverse flow case. The spoiler was yanked out by it's roots, and would most likely be a consequence of high rate of descent impact.

[Squawk_ident]

mm43

I now realize you are raising your question based on the 0133z position report with ETO SALPU 0148 and ETO ORARO 0200z. This raises an issue with RECIFE / ATLANTICO ATC as the filed plan showed the sector at M0.82 and it would now seem that the Captain had planned a reduction to M0.80 after INTOL. Somehow this didn't eventuate as the A/C continued to 'derniére position connue' - last known position at M0.82.


You got the point.
I knew the mp3 snippet release by the FAB . It's the only official information that TASIL was estimated at 0220. And the controller speaking to Dakar states "Mach 82" But this estimation is not correct at 0.82. It should have been 0211 something like this.

[woodja51]

I agree that the initial report is a bit light on any sort of conclusion.. as yet..but ...

and I am not Chuck Yeager...

so certainly not overly critical of the crew as they are a product of any system...

I still can't get away from the possible mishandled loss of airspeed reference ... not say that flying a jet in turb in alternate law is easy but if all that stuff happened and you just did.....well ..... nothing!! it should stay where it is.. ie throttles in climb detent ( as per loss of airspeed so no need to do anything as the auto throttle had already disconnected ..maybe have to move them if for some reason they went into thrust lock?..) pitch.. 5 degrees.. well it is probably a bit less than that anyway on a/p disconnect at FL350 so nothing to do there..much??- but I could be wrong...??

Faced with lots of ECAM and stuff in a short space of time what would anyone do... wings level , nose on the horizon and power set to climb. Yes yes hind sight you say..

(I vaguely remember 'nose above the horizon .. speed goes down... nose below the horizon... speed goes up... from my RAAF U/A recovery stuff..)


And as far as stalls go... have done this in the simulator once or twice and ...yes accept fidelity past limits and R/N etc may not make the real jet the same ....but I believe it stalls pretty much like any aircraft.. you know heavy buffet. etc which 'elevator forward sufficient to unstall the wings' works to fix... aft c/g maybe more unstable ..yes..spin prone B/A ratios and stuff maybe..

I think this is what we all really want to know.... how it managed to get away from the drivers, and if it was mechanical/environmental that started the sequence.. fine fix the fleet ( I see accelerated replacement programme in place)... but I don't see anyone grounding their jets as yet so guess the blame is going to come back to the pilots.... or never be known.

Time for training to look at these type of events and react accordingly.. but facts yet to be known so just ideas at moment.

W

[wall-e]

That's interesting

Air France 447 - AFR447 - A detailed meteorological analysis - Satellite and weather data (http://www.weathergraphics.com/tim/af447/)

[Nightrider]

I am beginning to wonder if the BEA formally asked to view the autopsies. I get the impression that the Brazilians are sticklers for procedure. The French may have asked informally relying on their formal status and been "rightly" rebuffed by the Brazilians. A formal request might have turned the trick.


Read between the lines, the BEA report does not give any statement about how or when a request to this effect has been issued. There may also be the attitude on the Brazil side that only an official channel (French embassy) can deal with such a request, whereas the BEA may have the attitude that they are the authorized communication partner.

SOPs are a good tool, however, they only work for the environment they are designed for. Two or more SOPs crashing into each other will most certainly contradict each other in several areas, a given fact we see in our job often enough if crew are changing employers....
"in my last company this was SOP, why is it not allowed here?"....

[LeandroSecundo]

Hi,

I am beginning to wonder if the BEA formally asked to view the autopsies. I get the impression that the Brazilians are sticklers for procedure

Read between the lines, the BEA report does not give any statement about how or when a request to this effect has been issued. There may also be the attitude on the Brazil side that only an official channel (French embassy) can deal with such a request, whereas the BEA may have the attitude that they are the authorized communication partner.Seem's from head .. it is a international law or a international agreement in the case of transmission of such forensic or other results in civil aircraft crash investigation.
Anyone can confirm ?
I think at this:
Annex 13 to the Convention on International Civil Aviation, which envisages full and free cooperation.
Convention on International Civil Aviation - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Convention_on_International_Civil_Aviation)

Aircraft Accident and Incident Investigation (http://209.85.135.132/search?q=cache:oUcVt2G930oJ:www.rnf.is/media/eydublod/Annex_13.pdf+%22Annex+13+-+Aircraft+Accident+and+Incident+Investigation%22&cd=1&hl=fr&ct=clnk&gl=be&lr=lang_en)


Bye.

[DJ77]

And the controller speaking to Dakar states "Mach 82" But this estimation is not correct at 0.82. It should have been 0211 something like this.


Squawk_Ident and mm43, I think this is unrelated with the accident but since you are doubting the positions/timing of AF447, just consider that, for whatever reason, the estimate for ORARO we read in the BEA's report is almost certainly erroneous. It should be about 0204 and that makes all other positions/estimates consistent with a GS of about 470 kt. In particular, 0220 for TASIL was correct.

[spornrad]

Speculation about human remains and autopsy results are at least inappropriate if not outright offensive, given this is a public forum that may well be seached e.g. by relatives of the deceased.

One of the worse examples lacking any respect to the victims as well as every decently compassionate person in my eyes is post #3130 http://www.pprune.org/5043385-post3130.html

Eventually BEA will obtain and study the records and release conclusions.

[SubsonicMortal]

I would like to read the pre-lim report that is posted on here somewhere but sifting through over 3000 posts will be a little time consuming. Can someone refer to the post number so I can jump to it?

Thanks

SSM

[Dave Gittins]

T'were in post #2995 (amongst others.)

http://www.aviaciondigitalglobal.com/newsFiles/20090702022842-4.pdf

DGG :ok:

[FrequentSLF]

I recall to have read somewhere in PPRuNE that on the A330 the manual selection of "Direct Law" is no possible, but can be forced shutting down the PRIMs and the SECs. If my recollection is correct, is it worth to consider that the crew was trying to get in direct law?

[takata]

Links to BEA (Bureau Enquête et Analyse)
. English page related to AF447:
News (http://www.bea.aero/anglaise/actualite/actu.htm)
. AF447 Interim Report (without Annexes) 02/07/2009:
http://www.bea.aero/docspa/2009/f-cp090601e1.en/pdf/f-cp090601e1.en.pdf
. AF447 Organisation of investigation 02/07/2009:
http://www.bea.aero/anglaise/actualite/af447/organisation.of.investigation.af447.en.pdf
. AF447 Findings 02/07/2009:
http://www.bea.aero/anglaise/actualite/af447/findings.af447.en.pdf
. AF447 Sea search operations 02/07/2009:
http://www.bea.aero/anglaise/actualite/af447/seasearch.af447.en.pdf

. French page related to AF447:
Bureau d'Enquêtes et d'Analyses (http://www.bea.aero/fr/enquetes/vol.af.447/vol.af.447.php)
. AF447 Interim Report (Including Annexes):
http://www.bea.aero/docspa/2009/f-cp090601e1/pdf/f-cp090601e1.pdf

S~
Olivier

[SaturnV]

I've reposted some surface current images in JB. Post#487 in the AF447 thread.

http://www.pprune.org/jet-blast/375943-air-france-jet-missing-25.html#post5044468

[lomapaseo]

JuggleDan

From a scientific reader's standpoint, there are two issues with this expose:
- The conclusion extends the findings of section 1.12.4 by adding that the a/c was not destroyed in flight without justifying this extension;
- The conclusion mixes as "established facts" on the one hand a long series of factual information and on the other hand a single non-factual conclusion (airplane was not destroyed in flight...).

My feeling is that the BEA is putting forward their theory (airplane was not destroyed in flight) as an established fact at a time when they probably don't have enough evidence to do so: as WF repeatedly points out, they don't have the autopsies' results yet.


I tend to read their releases a little bit higher on the surface, (I never trust translations). In other words we (the reader) should be less sure of our conclusions.

At this point I haven't seen anything that concludes what started the airplane to fall out of the sky. Like Will Fraser intimated, after it fell is all secondary to what we need to know to prevent a similar accident.

[BJ-ENG]

A reminder of the significant damage inflicted on an airframe even during a
successful ditching - US Airways Flight 1549 (Airbus A320-214 – N106US
January 15, 2009).

NTSB Structures Group Chairman’s Factual Report:
http://www.ntsb.gov/Dockets/Aviation/DCA09MA026/418719.pdf

See photos 12 through to 15 showing bulkhead and rear tail cone damage looking aft from frame 70. Displacement of the tail cone and bulkhead rupture would appear to be the result of the hydraulic action created by water ingress through the damaged underside (FR50+ photo's 16, 23, 24 in Attachment 2 - Addendum 1).

Attachment 2:
http://www.ntsb.gov/Dockets/Aviation/DCA09MA026/418716.pdf

Attachment 2 - Addendum 1:
Damage to underside:
http://www.ntsb.gov/Dockets/Aviation/DCA09MA026/419640.pdf

Attachment 4:
http://www.ntsb.gov/Dockets/Aviation/DCA09MA026/420144.pdf

Attachment 1 to the Factual Report Figures:
http://www.ntsb.gov/Dockets/Aviation/DCA09MA026/418699.pdf

See also:
FAA Report AR-95/54 Transport Water Impact and Ditching Performance:
http://www.ntsb.gov/Dockets/Aviation/DCA09MA026/419887.pdf

Original src:
CD List Of Contents (http://www.ntsb.gov/Dockets/Aviation/DCA09MA026/)

[Hyperveloce]

Hi there
The BEA report states:
"The tail fin was damaged during its recovery and transport but the photographs available made it possible to identify the damage that was not the result of the accident. The middle and rear fasteners with the related fragments of the fuselage hoop frames were present in
the fin base. The distortions of the frames showed that they broke during a forward motion with a slight twisting component towards the left." (p.35).
On another hand, it is said that most of the debris suggest a strong vertical decceleration and the action of strong compressive forces:
why don't the middle and rear fasteners of the VS with the related fragments of the fuselage hoop frames (who suggest a forward motion & slight twist) show this strong compressive structural effect ?
That the connecting brackets between the floor and the walls were bent
backwards also suggest an horizontal acceleration component ? Shouldn't the thousands of vertical Gs of the vertical impact on the belly have compressed the fasteners and fuselage hoop frames in the same way ? Why only a foward motion with a slight twist is seen on the VS ?
Jeff

[ClippedCub]

Why only a foward motion with a slight twist is seen on the VS ?

One explanation is the afterbody broke off in-flight and impacted independantly.

Another is the horizontal failed down and aft, in-flight, taking pieces of the frames with it. Both scenarios would give the illusion of the VS failing forward, when in fact the after body failed away from it.

[Chomolungma]

Well I think that what they are thinking is that it hit the surface of the water at level attitude so the deceleration from the wings and fuselage ripped the VS off forward before the empennage hit. Not sure where the damage to the rudder came from though...perhaps the tail cone.

[Will Fraser]

Continue to be far less than fluent in AB Flight Law. In an attempt to unwind back toward initial upset (I am convinced there was one), There is an interesting video of a HS failure on a light twin at high speed at low altitude, a Partenavia. The a/c was attempting a crisp pull up into a "loop", and the HS failed, downward, as you would expect. If 447's nose had dropped, perhaps a last gasp effort of the a/p as it dropped out, having sensed the Unreliable a/s as low, and with a raised AoA, would be for it to lower the nose. It is possible that crew, perhaps surprised and not a little overwhelmed at the auto disconnect, were thereby confronted with an overspeed a short while later. If it developed, and they found Alt. Law unhelpful in an urgent need to arrest a/s, would that explain their attempt at Direct Law by defeating two critical computers by switching them off? (FrequentSLF posed this bit).

If in any case the HS was overloaded in a high speed input, suffered damage, and failed downward, that might be considered consistent with a VS failure as BEA divined, "Forward" would then be a misunderstanding, but still retain validity, though not a demonstration of failure at impact with water.
Why not give BEA all latitude in 'translation' issues, and 'mistakes' in jurisdictions or protocol, to this extent, the document still reads biased, impatient, less than technical, and political. I seriously expect that BEA would want to correct their omission of all scientific 'medical' information, given that the passengers may be able to demonstrate in many ways what even the CVR/FDR could not.

Again, I think it likely some failure of the tail and/or aft pressure bulkhead occurred at high speed, post ACARS. Even if the tail failed during ACARS tx, is it not possible evidence was 'backed up'? Also, ACARS is mx, it doesn't troubleshoot? Rudder Travel Limiter loss could be its 'understanding' of a catastrophic empennage failure? Though the VS was gone, the computer may sense it as 'there goes the RTL'. With a loss of hydraulic pressure consistent with separation, its tx might be what ? If the VS loss happened when the ACARS was 'busy' or after 0214? With the possibility of statics problems and/or pressure loss in cabin, the warning may be doing its task as designed, 'faster than 1800'/min.' is consistent with a complete loss of pressure in the cabin, is it not?

My Edit. Regardless who is 'responsible' for autopsy data to be missing from the report, it is a glaring error. If the argument gets more attention than the data, you will know it was deliberate and political. No one could notice its absence without demanding its subsequent inclusion via 'append'.

IMO

[Hyperveloce]

retaining the BEA suggestion that the aircraft did impact the surface in one piece, could these two types of structural distortions (forward motion & slight twist versus strong vertical compression) also suggest that the aircraft impacted the surface at high velocity with mainly a vertical component (as said by the BEA) but with a positive pich, not only on the belly ? (tail impacted first, snapping off the VS, bending backward the connecting brackets between the floor and the walls, immediatly followed by the belly impact and the compressive stress ?).
Jeff

[einhverfr]

Hyperveloce:

why don't the middle and rear fasteners of the VS with the related fragments of the fuselage hoop frames (who suggest a forward motion & slight twist) show this strong compressive structural effect ?
That the connecting brackets between the floor and the walls were bent...

Here is my take. The VS is a large and comparatively massive bit sitting on the end of the tail, with a small connective cross section facing downward against the tail cone. With strong vertical deceleration, the VS is going to compress against the upper wall of the tail cone and in this case, probably punch through, breaking the body around it. The forward deceleration then causes the VS to continue through the air forward relative to the rest of the aircraft.

A slight leftward twist in the airframe would affect damage on the VS, and might affect its tragectory after departing the airframe. However it wouldn't affect the rest of the scenario substantively.

I don't think a forward failure would necessarily be seen from an in-flight separation because of the aerodynamic forces involved.

[echosierra69]

VS broke in a forward motion : so why the bottom part of the rudder is missing?
Assuming that the horizontal stabilizer is made of the same composites as the VS it should have broken in the same manner as the VS,for the same reason and float similarly, never mentionned anywhere.
From the photos of the brazilian marine the VS was alone (no other debris nearby) as it seems to me that some parts with the same buoyancy should have been found in its vicinity as their course after hitting the sea would only be determined by the currents.
No other debris around the VS would probably mean that it attained the water already separate from the main part of the a/c...

[Nosmo_King]

A chunk of the bottom part of the rudder was lost during the recovery process.

Compare the following two images.

1) When they found the VS

foto_3.jpg picture by DorianBanks - Photobucket (http://s635.photobucket.com/albums/uu79/DorianBanks/?action=view&current=foto_3.jpg&newest=1)

2) During recovery

6.jpg picture by DorianBanks - Photobucket (http://s635.photobucket.com/albums/uu79/DorianBanks/?action=view&current=6.jpg&newest=1)

[Chomolungma]

The preliminary report does mention they found pieces of the horizontal stabilizer. I don't know where it was found or if they made public that info.

[EMIT]

I see a lot of questions and theories based on English terms in the preliminary report.

"leur examen visuel montre que l’avion n’a pas été détruit en vol ; il paraît
avoir heurté la surface de l’eau en ligne de vol, avec une forte accélération
verticale."

is translated as

"visual examination showed that the airplane was not destroyed in flight ; it appears to have struck the surface of the sea in a straight line with high vertical acceleration."

The expression that is underlined (by me) is interpreted by some as meaning that the airplane fell almost vertically from the sky (like a brick would do), or that it dove nearly vertically into the sea.

The literal translation is "in the dircetion of flight", meaning, not sideways or backwards.

The "vertical acceleration" is treated by some as a sort of indication of speed of the entire aircraft. However, it is merely a description of the line along which the acceleration took place (and because the acceleration was in such direction that the movement of the parts was brought to a stop, a laymen would call it a deceleration). The deformation observed so far points to hitting the water with the velocity of the aircraft mainly along the longitudinal axis and downwards - that's all.

As to the terminology pertaining to the bodies: "relatively well preserved" is accurately translated, perhaps it means, besides "relatively in one piece" also "not yet decomposed" (sorry, not meant to insult any sensitive soul).

[Will Fraser]

The impact's description is confusing. It may or may not be purposely so. Vertical impact without forward movement extinguishes the need to even mention a 'direction', any direction would be irrelevent. If they meant 'in the direction of flight' I challenge them to support their conclusion. How in God's name can a heading be determined at impact? Even if it was 'important'. To prove the a/c fell 7 miles not experiencing a heading deviation? There is something more here than 'misunderstanding'.

What would BEA (and AB) have to gain by a statement that the 'direction of flight' (or even a 'straight line') was determined at impact? the intimation that the a/c was 'under control' to the 'end'. Non? Similarly, why the absence of pathologies? There is no excuse for not including the medical data. Do the discrepancies in condition of the passengers challenge your visual conclusion that the a/c "hit in one piece?"

The a/c hit intact. No scrutiny of the data, just 'intact'. These a/c don't 'disintegrate', you see. Likewise, 'From visual inspection', the Vertical Stabilizer' was attached until the a/c hit. Wait, we thought you said there was no forward momentum and the a/c landed (sic) flat? But it failed 'forward'. Quite the trick. Also, if there was a 'left twisting force' wouldn't that infer a rotation at impact, and not 'in a straight line'? Is anyone else having these problems with the report.

If the a/c was intact at impact, wouldn't it obviously hit along its longitudinal axis?

[Storminnorm]

Linge de vol, just that, Line of flight. Horizontal.

[ARFOR]

Commonality of hypothesis:-

The question remains, the mode of upset?, and the descent to the surface (with or without flight crew intervention)?

re: attempted ditching, what would they have needed?

1) An intact or at least flyable airframe; AND
2) Attitude reference (visual or synthetic); AND
3) Airspeed indication and thrust for [N1 and pitch] procedure until through the air data anomalies; AND/OR
4) Descent into thicker air where thrust/underspeed would become less critical (increased handling margin); AND/OR;
5) Following thrust loss (no indication that happened) a glide descent.

It follows that:-

A. If the aircraft had descended, or flew through a rare WX generated air data collection systems problem (still hypothesis only) and eventually exit (in a recoverable/flyable state with thrust available):-

1) - If no other damage had occurred, the lost air data would eventually return (as per similar events) and the crew could fly out presumably (as per similar events) and recover/return to normal flight (including ACARS output); OR
2) - If the aircraft suffered engine failure, it could be recovered to a glide for troubleshooting (would it still output ACARS?), relight/restart and return to normal flight, or ditch; OR
3) - The aircraft suffered structural failure due to airframe overloading (commanded or aerodynamic loads/or both) + possible engine failure resulting in terminal descent in one of the ‘uncontrolled/uncontrollable modes’ discussed at length in this thread; AND/OR
3a) - The aircraft may have been in a situation with (any of the following) combinations of unusual attitude, O/speed, Stall, Spin, Thrust loss, Asymmetric thrust, insufficient or incomplete control authority (surfaces/systems) with insufficient airframe AND/OR control authority AND/or altitude remaining to affect a recovery to normal flight

B. Clearly, unfortunately it did not recover normal flight. Why? Possibilities:-

- Loss of flight instrumentation systems (continued)
- Loss of other systems after 02h13+
- Loss of thrust; and/or
- Loss of airframe components critical to controlled flight; and/or
- Stalled flight, unrecoverable

Outcome:-

Water impact flat at high (vertical) speed is going to be similar to the BOAC 707 at Fuji.

For those that have not seen them, the photos from above of the wreckage of the 707, latitudinal parts layed out pretty much as expected with a vertical profile (FLAT), main gear legs, wing roots, fuse parts, unsurprisingly where they were expected to be, flat as a lizard drinking!. The compression on impact reduced most components to less than 1m in vertical dimensions. That is the fuse, wings and all else;-

A water impact flat (at high speed) is little different to a hard surface!
BEA says (they think) a horizontal fuse (or near enough), vertical impact with the water??

Q1. Would a galley wall with packs installed not compress to a foot tall or so with that sort of vertical inertia impact?
Q2. Would the other visible (photo) items recovered such as medical kit be as ‘uncompressed’ as shown in a fuselage high g flat impact?
Q4. would an attached VS look as pristine along its vertical proflie if it had hit the hard deck at high G?
Q3. Why would most of the debris sink (not much on the surface to recover)?

Some of you have narrowed in on the ‘likely’ failure scenario. Is that important? Only if, there is an inherent weakness in the airframe! Do I think there is an inherent weakness in the airframe? NO

Do I wonder about the flight management/C of G/protections that will ensure the airframe is not put in an ‘outside of reasonable/design envelope’ mode, YES!

WHY?

You all are close me thinks!!

[ClippedCub]

Compare the following two images.

1) When they found the VS

foto_3.jpg picture by DorianBanks - Photobucket (http://s635.photobucket.com/albums/uu79/DorianBanks/?action=view&current=foto_3.jpg&newest=1)

2) During recovery

6.jpg picture by DorianBanks - Photobucket (http://s635.photobucket.com/albums/uu79/DorianBanks/?action=view&current=6.jpg&newest=1)

Allowing for forshortening from photographic aspect, the two photos indicate the same damage and extent.

[overthewing]

I wonder if the description of the bodies as being '...relatively well preserved. All of them were handed over to the Brazilian Navy to be transferred to the Recife morgue. At this stage of the investigation, the BEA has not yet had access to the autopsy data.', is to forestall any claim by the Brazilians that the bodies were not in a good enough condition for the autopsies to reveal useful information?

It seems extraordinary to me that the autopsy information has not been shared with the BEA. The injuries to the bodies must be one of the biggest clues about what happened on the plane.

I know the BEA had scheduled their preliminary incident report for end June. Is there not a similar deadline for a preliminary autopsy report?

[takata]

Will Fraser:
Again, I think it likely some failure of the tail and/or aft pressure bulkhead occurred at high speed, post ACARS. Even if the tail failed during ACARS tx, is it not possible evidence was 'backed up'? Also, ACARS is mx, it doesn't troubleshoot? Rudder Travel Limiter loss could be its 'understanding' of a catastrophic empennage failure? Though the VS was gone, the ACARS may sense it as 'there goes the RTL'. With a loss of hydraulic pressure consistent with separation, its tx might be what ? If the VS loss happened when the ACARS was 'busy' or after 0214?- 2723 Flight Control Ruder Travel Limiter Fault Cockpit Warning is documented beyond any doubt. RTL is a function of airspeed which fault once speed data became unreliable, then it is displayed in cockpit. This is totally unrelated with Hydraulic Systems and failures.

But one may decide that both CMS (Central Maintenance System) is unreliable and is displaying by ACARS some erratic faults unrelated to the right system in order to bend the facts to theory. Then, instead of displaying 29. Hydraulics faults on the three hydraulic circuits linked to the rudder (Blue (B), Yellow (Y), Green (G)), the faulty CMSs will use Flight Controls warnings instead.

With the possibility of statics problems and/or pressure loss in cabin, the warning may be doing its task as designed, 'faster than 1800'/min.' is consistent with a complete loss of pressure in the cabin, is it not?What would be consistant with a complete loss of cabin pressure would be a 21. EXCESS CAB ALT, CRC aural Warning, Master Warning displayed, indicating that the Cabin altitude is exceeding 9,550 ft at cruise altitude.

The cabin vertical speed advisory (cockpit signal) is related to the controller ability to monitor the DeltaP (external and cabin differential pressure) changing in excess of 1,800 ft/mn. A change of aircraft indicated altitude (real or instrumental) would trigger such an advisory if the differential pressure is in excess of the function.

But one may follow the same logic as for the RTL and consider that as a major failure of the whole pressurization system, because the tail (fin) separated in flight... consequently, "you will know it was deliberate and political".

S~
Olivier

[woodvale]

Nice as it would be to know exactly what happened and why, we can still learn a great deal from this accident by examining what might have happened.

It is quite likely that they flew unintentionally into a CB.
1. Do we interpret Wx Radar correctly at high altitude?
2. In areas of probable turbulence, is our seat harness secure enough to make us part of the airframe and thus able to concentrate on flying the aircraft?
3. Do we understand the forces involved within a CB?
4. Unreliable airspeed as trained in the Simulator is normally an academic exercise to fly some sort of approach. It does not address the problem of it occurring in turbulence. Can we maintain an attitude on the standby AI irrespective of what else is happening?
5. As Commanders with a heavy crew, when do we choose to take our rest?
6. Engaging the AP at 200’ and then disengaging at 500’ gives the passengers a very smooth ride but it degrades our motor skills eventually. Are our handling skills what they were or what they should be?
7. Most importantly, do we think and plan ahead or do we just react when there is a problem?

The phrase used in almost every airline is that “Safety is our highest priority!!” We all know this is only true within financial limitations. WE ARE THE SAFETY ENFORCERS.

What have I learnt and what will I do different in the future?
In answer to my points above.
1. In the vicinity of CBs at high level, modern digital radar Green is not good. In VMC conditions, in the vicinity of CBs, I will look at the lovely clouds but also concentrate on what I can get out of the radar picture by manipulating the radar controls so that in the middle of the night I will know what the picture may mean.
2. I will use the top straps in anticipation rather than when it happens, I always use the bottom one..
3. I’ve never had a problem with this, CBs scare me. On 3 occasions close to them I’ve suffered the effects of engine icing at TATs below -40°. (warmer than this I would have had the EAI on anyway)
4. I’m fortunate enough to have been trained in the old days, I can remember well enough but these days we don’t train how to cope with limited panel and disorientation. In any case, no matter how good a Sim is, the seat of the pants feelings in there are not real. This is the crux of the matter, something occurred that put them into a CB, they lost control and the main instruments. Having got in there, I doubt may of us would have survived.
5. I have never left the flightdeck when passing the ITCZ unless there has been another Captain in the left seat.
6. I understand that airline managements are accepting that the pendulum has swung too far, we should all be encouraged soon to occasionally, when circumstances are right, fly manually. Even a few minutes of handling will reconnect eyes, hands and brain but we must be conscientious, don’t just fly manually in CAVOK.
7. I’m Old, I’m not Bold but, I’m always thinking, “WHAT IF”.

Possibly this post will be ridiculed, more experienced pilots will understand it, I hope some less experienced pilots will just think, without jumping down my throat.

[p51guy]

woodville,

Yes, your post probably won't last long. Being an old pilot too and also trying not to lose my basic skills before auto everything took over I hand fly some on each flight. Most of my posts get deleted if I question how well the automatic airplane pilots can hand fly if the automatics and primary instruments fail. But a few readers see it before it goes away. Good luck.

[takata]

ARFOR:
Commonality of hypothesis:
[...]
2) - If the aircraft suffered engine failure, it could be recovered to a glide for troubleshooting (would it still output ACARS?, YUP!)I don't think so. In case the aircraft suffered double engine failure, it should switch to EMER ELEC mode with only HF1 and VHF1 available => No more ACARS by SATCOM.

woodvale:
3. I’ve never had a problem with this, CBs scare me. On 3 occasions close to them I’ve suffered the effects of engine icing at TATs below -40°. (warmer than this I would have had the EAI on anyway)This is an important point and such an issue is also relevant considering AF447 case, at least, as much as the never ending 'Rudder & Computer glitches" thesis, already discussed to death, as well as the spin/stall unrecoverable upsets.

Here is a document about such kind of issue from the 44th AIAA Aerospace Sciences Meeting and Exhibit, 9 - 12 January 2006, Reno, Nevada:

The Ice Particle Threat to Engines in Flight
http://airs-icing.org/AIRS_II/AIAAReno2006/AIAA-2006-206-739.pdf
Authors:
*Jeanne G. Mason - Boeing Commercial Airplanes , Seattle WA, USA, 98124
*J. Walter Strapp - Environment Canada, 4905 Dufferin St., Downsview, ON, M3H 5T4, Canada
*Philip Chow - Honeywell International, 111 S. 34 St., Phoenix, Arizona, USA, 85034

Abstract:
This paper discusses jet engine powerloss and damage due to ingestion of ice particles. In the mid-90s several commercial airplane jet engines experienced more frequent powerloss in ice particle conditions, resulting in a focused investigation, and a greater awareness that led to recognition of similar events on other aircraft. Since the mid-90s, events have been more numerous, and costly, and have generated greater industry interest. These events have been predominately associated with flight at high altitude near deep convective systems, often in tropical regions. Data are presented from flight-testing and an event data base to support the contention that the events are caused by ingestion of high concentrations of ice particles, and that supercooled liquid water is either of secondary importance or not required. The basic theory of how ice accretes in the engine by this process is described. Complex issues facing industry to mitigate the problem, and simulation of the ice particle environment are discussed.

Everyone should read it and comment.
S~
Olivier

[bobusse]

Woodvale,
I rushed to keep a copy before it desappears.
How right is your contribution.
Again,BRAVO

[ARFOR]

takata Re: Resumption of ACARS output (following dual ENG FAIL and EMER ELEC) :-

If the RAT deployed, no ACARS dice eh?

Controlled flight prior to ENG FAIL? ACARS?

Irrespective, are you suggesting they might have entered a 'controlled' glide?

[PJ2]

woodvale;
Possibly this post will be ridiculed, more experienced pilots will understand it, I hope some less experienced pilots will just think, without jumping down my throat.
Your response will only be ridiculed by those who don't fly or don't know the 330 yet want instant answers anyway. You know exactly what you're talking about.

To you, to p51guy and others who fly but have essentially left this thread to the guessers, we know the lessons are there for the patient and wise who are starting out in this career and that is where to seek best value from this thread. Pro-active decision-making and avoidance are the keys.

I suspect here very strongly but am not allowed to say so because I have no "evidence", that this crew likely went from benign flight conditions with some moderate turbulence to a rapidly degrading airplane in both the technical and controllability senses in less time than it takes to read this post.

At 0210Z, it was already too late. Those who wonder why no distress call was made do not comprehend such circumstances or the rapidity with which such things occur or the ensuing chaos and strange motions, sounds, sensations and behaviours of a once-familiar aircraft and operating environment.

Someone said a transport category aircraft loses control "gracefully" - very true, simply due to it's mass, and this is the very aspect which makes any actions and any recovery at high altitude, (as testified by those who have done high altitude stalls), dubious, especially in the circumstances this crew found themselves.

It's all been said in a hundred different ways, and the focus on minutae about how such a mass behaves in a stall, one's definition of "flat" spins etc etc, is all post facto.

Woodvale, your "up front during weather" notion is part of that kind of preventative thinking. Everything after 0215Z or so is after the fact.

takata;

I will take time to read the suggested document thank you. I understand your reasons to suggest a controlled glide.

In response to present posts,... I suggested a dual engine flameout last week but the notion was never responded to.

I consider this outcome a distinct possibility if what the BEA said actually happened the angle of attack would be such that the airflow would no longer be "through" the engines but perpendicular to their axis and as such would flame out.

Such a scenario has significant outcomes for hydraulics, electrics and pressurization. The RAT, which, (going from memory) would deploy with the loss of either hydraulic pressure or AC1 & AC2 busses, would not be able to develop hydraulic presssure and there for power the emergency generator, for the same reason. That would mean that only VHF1 would be powered, and that, only by the batteries.

[falconer1]

BRAVO !!!

best post in the whole thread!!!!

Thank You again

[takata]

ARFOR:
takata Re: Resumption of ACARS output (following dual ENG FAIL and EMER ELEC) :
- If the RAT deployed, no ACARS dice eh?
- Controlled flight prior to ENG FAIL? ACARS?
Irrespective, are you suggesting they might have entered a 'controlled' glide? 1. As far as I studied the system => no ACARS (RAT or not). I may be wrong.
2. If I'm suggesting they entered "controlled glide"? => YES.

Why?
a) see my post here: http://www.pprune.org/5011256-post2085.html
The drift doesn't fit with a 0210-0214 close crash. This was a pure constatation, no theory (agenda) behind, based only on the BEA genuine documents, not on various unreliable press reports, not on rumors, and I still stand correct following this actual Interim report.

b) the area searched for the CVR/FDR, until yet, is unsuccessfull but doesn't cover enough to the southern area (20-30 NM farther). This is ruling out the fast crash (0214 or close) hypothesis and it is the best case to have a chance of discovering the wreckage.... OR, the pingers were destroyed (worst case).

S~
Olivier

[ARFOR]

PJ Have you a view on the SATCOM in EMER ELEC (RAT or NOT) config?

takata Re: Your glide (complete airframe) theory:-

That depends on where the Brazilians found occupants (position, Lat long), verses the occupants found by the French (position, Lat long).

Do you agree that the two groups were miles apart (minus drift) and could not reasonably have arrived on the surface in the same location?; and then (in the days following) drifted apart (in such dissimilar directions) in two distinctly separate groups?

Following on, which group position (minus drift) are you basing your [pinger/ aft fuse wreckage] assumptions on?

[Jim Croche]

Woodvale, PJ2 and all the many posters (especially including the non-pilot experts on Satcoms etc) who have enlightened us all, thank you!

Woodvale, I sincerely hope that every young pilot who thinks he's untouchable reads your post but somehow I doubt it. So it's up to those of us who have survived to still fly, to ensure they're made fully aware of the dangers of not keeping their handling skills up to scratch and of the limitations of weather radar at high altitudes especially in tropical areas.

Now which airline in the middle east has forbidden their pilots to handfly the a/c?

[einhverfr]

PJ2:


Someone said a transport category aircraft loses control "gracefully" - very true, simply due to it's mass, and this is the very aspect which makes any actions and any recovery at high altitude, (as testified by those who have done high altitude stalls), dubious, especially in the circumstances this crew found themselves.


That might have come from misreading one of my posts. My point though was that the A330 is designed for the flight controls to degrade gracefully, not that the aircraft loses control gracefully. This is why one has 5 flight control laws (Normal, ALT1, ALT2, Abnormal Attitude, and Direct), so that when some protections are not available due to technical reasons, or are not applicable to the current aircraft state, whatever protections are applicable and technically available are used.

Of course gross upsets can happen very fast. I am hoping that folks did not take from my post that I was saying this couldn't happen.... ;)

[takata]

ARFOR:
takata Re: Your glide (complete airframe) theory:-
That depends on where the Brazilians found occupants (position, Lat long), verses the occupants found by the French (position, Lat long). Absolutely not.
The body recovery (and most of the wreckage also) was maped and time stamped (French & Brazilian), I used the official documents released by the BEA showing the day by day recovery. The pattern is obvious: the drift between 6 and 10 June was to the North. Very few bodies (1 or 2) were out of this pattern but not very far away (considering 5+ days at sea), and it may be easily explained by the turbulence of this area.

Do you agree that the two groups were miles apart (minus drift) and could not reasonably have arrived on the surface in the same location?; and then (in the days following) drifted apart (in such dissimilar directions) in two distinctly separate groups?No. Documents are not showing such a "fact".
Few maps from Brazilian presentations suggested this separation but, in fact, they matched totaly the BEA maps I reported. The explanation was that the Brazilian maps had no dates of recovery, then bodies recovered the 6th were not at the same places as bodies recovered the 9th, but were on the same pattern following the drift.

Following on, which group position (minus drift) are you basing your [pinger/ aft fuse wreckage] assumptions on? See above, there is only a single group. I took each day the northern most recovered and made an estimation of the total drift that I reported for the previous five days (0.4 m/s average). It doesn't give an accurate estimate of the crash area but it is showing that the wreckage distance is much further South (and possibly South-West) from the actual area searched based on the close to 0214 impact hypothesis (40 NM circle around 0210 position).

Beside, the tailfin was in the middle of the body pattern, following the same drift, and was recovered June 7th. I discarded other wreckages due to size, density and winds effects.

S~
Olivier

[PJ2]

ARFOR;
PJ Have you a view on the SATCOM in EMER ELEC (RAT or NOT) config?
The AOM/FCOM does not show SATCOM or ACARS available in the EMER ELEC Config, RAT or no RAT QRH procedures.

If the engines are supplying hydraulic power for the emer gen, VHF1 and HF1 are available. HF1 is not available under any other configurations; VHF1 is.

Remember, the services which must be available are under emergency circumstances and which must contemplate using the emergency electrical (hydraulic) generator run either by the engines or the RAT (very bad circumstances) right down to the ship's batteries, are prioritized towards the safety of the aircraft, not communications. "Aviate, Navigate, Communicate" is a bread-and-butter way of expressing these priorities. Ship's batteries are certified for about 30 minutes (if I recall), even under these severely reduced services.

The QRH indicates under Navigation equipment, that:

IR 1 & 3 are available until the batteries exhaust themselves - about 30 minutes;
IR 2 is available for 5 minutes;
ADR 1 is available until the batteries exhaust themselves
ADR 3 is available under engine hydraulic power (driving the emer gen) but is not available otherwise;
ADR2 is not available.

SATCOM/ACARS etc would be among the first services to be lost, by design, under the EMER ELEC Config.

The APU battery cannot be used for any other purpose other than starting the APU.

[PJ2]

einhverfr;
That might have come from misreading one of my posts. My point though was that the A330 is designed for the flight controls to degrade gracefully, not that the aircraft loses control gracefully. This is why one has 5 flight control laws (Normal, ALT1, ALT2, Abnormal Attitude, and Direct), so that when some protections are not available due to technical reasons, or are not applicable to the current aircraft state, whatever protections are applicable and technically available are used.

Of course gross upsets can happen very fast. I am hoping that folks did not take from my post that I was saying this couldn't happen....
Yes, I did mis-recall/misunderstand that statement, thank you. I was thinking more of "mass" of an airframe than I was of software design; to me, both outcomes, (degradation of control laws, LOC) are however, "graceful" in the sense that they happen relatively slowly and, in the case of loss of control of a large (widebody) airliner, insidiously, which is all I meant. Thanks again for correcting the impression.

[ARFOR]

PJ Thankyou, so we know that the aircraft had no thrust and/or stable (SATCOM aerial up) attitude after 02h 14

takata yes I followed that closely. My point, from the 'mapped positions' is:-

We cannot discount aircraft sections separating at altitude based on this drift theory (alone)?

In other words, even if (hypothetically only) the aircraft fuse separated into sections at FL350 or thereabouts, (or anywhere between FL350 and SL), what lateral dispersal could we expect on the surface (worse case)? 2,5,8 - 10nm?

Drift from those hypothetical (unknown) positions over days?

I am not saying a controlled descent was not possible, just pointing out that the dispersal does not definitively say one or the other!

The known wreckage, well that’s another story (previous post/s)!

[p51guy]

Just the evidence of high vertical G loads indicating it hit fairly flat on it's fuselage by itself doesn't mean it was in a flat spin. The Amsterdam recent incident crashed much like that landing flat but with a high sink rate. If they were in a spiral dive and saw the ocean coming towards them in the final seconds they would attempt to pull out wings level but if they couldn't they might hit flat or even nose up with a very high sink rate at impact. I hope somebody finds the black boxes to find out exactly what happened.

[BOAC]

6. I understand that airline managements are accepting that the pendulum has swung too far - excuse me for plucking from your good post, but do you have good evidence of this? It would be welcome news if so.

[barit1]

rgbrock1 -

The aero loads during a spin are not destructive; a spin starts with the aircraft in a stalled (low-speed) condition, and even in a flat spin the aircraft should be expected to hold together. The rate of descent is of course high, and in an intentional spin a pilot will be planning his recovery (or escape) at a generous altitude.

In an airliner-size aircraft, though, the long fuselage means that things near the front or the aft of the ship are subjected to a lot of centrifugal force, perhaps enough to be incapacitating. (Think tilt-a-whirl at the carnival.)

[Cazman]

If the black boxes are recovered, which is starting to look unlikely, how much good would the FDR data be? Wouldn't the data recorded be unreliable if it is coming from the computers and flight directors?

Isn't the data recorded derived from the same computers that sent the ACARS messages indicating there were problems, or does the FDR get it's information from an independent source?

I'm starting to wonder if the FDR will be just as confusing (for lack of a better term) as the ACARS messages.

I think our best shot at answers would be the CVR.

[Will Fraser]

EMIT

Your post is noted. My point in focusing on the parts of the report that are not conclusive but purport to be and the potential for people to "misunderstand" is to show how unprofessional it is. In a long life I have worked as both an investigator and a technical writer. I will leave you with this.

'ligne de vol' - Line of flight. period. The French have a word for horizontal which would have been my choice to convey 'level'. The word is, 'horizontal'. Words have meaning, and subtly guide the reader.

The a/c was not 'flying', it was crashing. Minor? Depends on one's perspective. Here we casually trash the journalist who can't get things right and displays a vocabulary that is amateurish. Do we not hold the investigators to a higher standard? Why make note of bodies discovered that were 'apparently well preserved', but not mention there were others?
No explanation for a lack of Medical data? 'We hadn't received the results' does not wash, IMO.

The Chinese say, "A half truth is a whole lie."

[takata]

ARFOR:
takata yes I followed that closely. My point, from the 'mapped positions' is:-
We cannot discount aircraft sections separating at altitude based on this drift theory (alone)?
In other words, even if (hypothetically only) the aircraft fuse separated into sections at FL350 or thereabouts, (or anywhere between FL350 and SL), what lateral dispersal could we expect on the surface (worse case)? 2,5,8 - 10nm?What the "drift" hypothesis is pointing is that the aircraft flew back at some point after 0210, turned and glided back before crashing at a distance of about 100-120 NM from where the first bodies were recovered.

If things happened like that, and in order to glide that far, the aircraft can't have broken at 35,000 ft or below, and the airframe would have to be fairly well preserved until the crash happened (with most of her control surfaces still there). I have no theory how she finaly crashed but a configuration where the pilots may have lost control of the aircraft at some point (like battery exhaustion) is much easily understandable than just because of an unreliable speed event (especially when this same company A340/330 division experienced 9 of this events during the previous 2 years - this problem was know by the pilots flying those aircraft).

Next, the "breaking appart" hypothesiss is based on "severe (forte) to extreme turbulences" which are unproven at the first place. At 0210, the turbulence level of this flight would have ranged from no turbulence to moderate (auto thrust setting). There was no communications about any turbulences from this flight ever contrary to the tale raported by Air France (1st June) at the same time as the lightning story (none or very few lightning activity reported by meteorologists in the area).

I am not saying a controlled descent was not possible, just pointing out that the dispersal does not definitively say one or the other!
The impact zone, if discovered, will reveal where and when (aproximately) this aircraft crashed and will tell us a lot about how the aircraft managed to end there. This will rule out many hypothesis by this simple fact. No impact zone discovered so far 40 NM around 0210 position is telling us also that the chance that it crashed in this already searched area are not as much probable, but not totally impossible if the pingers are not working for whatever reason.

On this map below, I reported the sea current forecast made 5th June by the French Navy Hydrographical Service (SHOM). Using the vectors and the currents strength level boundaries (up to 0.6 m/s at some points, blue values) , this give this curved line where I reported back the daily positions from d06 to 01 (crash time). Sea surface currents are only one part of the drift vector and the winds are predominently from South-East, which, depending of the weather can build this northern drift vector.
The search area is also reported and is still short of the crash area predicted (about 80 NM South-South-West of Last report).

http://takata1940.free.fr/images1/drift.jpg

[MATELO]

Can i surmise that a flat spin is possible, but highly unlikely.

So, what are the chances that there was a multiple instrument failure on board 447. if this was going on, what are the chances the pilots forgot the most important thing...... Fly the plane.

Did they get carried away with progressive faults and didnt notice the aircraft was in a steady descent for a number of mins, only for it to become more critical at lower altitudes. Did they only realise how low they were when they heard the "terrain, pull up" alarm (various accidents have been attributed to pilots worrying about minor faults, and fogetting to fly the plane). Would this result in them pulling as hard as they could on the stick, resulting in the plane trying to climb out, only to hit the ocean at a worrying speed and angle.

Not passing judgement on the aircrew, just offering up another suggestion.

[fyrefli]

The impact's description is confusing. It may or may not be purposely so. Vertical impact without forward movement extinguishes the need to even mention a 'direction', any direction would be irrelevent. If they meant 'in the direction of flight' I challenge them to support their conclusion. How in God's name can a heading be determined at impact? Even if it was 'important'. To prove the a/c fell 7 miles not experiencing a heading deviation? There is something more here than 'misunderstanding'.

Unfortunately, "en ligne de vol" happens to be one of those phrases that, when translated, is apt to subtly change meaning, whichever of the various English alternatives is used.

A someone whose French was close to fluent at one time and having just refreshed it with a week's flying and chatting to French pilots in the Alps, I agree with EMIT, a few posts ago, that its use in the original French is almost certainly intended simply to convey that the BEA believe the aircraft hit the water with its horizontal motion in the usual direction and not to imply anything about its heading.

I was tempted just to send this as a PM but the English translation seems to be causing more than localised confusion. Apologies to the mods in advance if you find this post unnecessary.

[SaturnV]

takata, with respect to drift, and possible point of impact, and whether there was a controlled glide or not.

First image is of the search grids for June 1 as flown by the Brazilian Air Force.

http://i136.photobucket.com/albums/q199/tahitiplage/SNAG-0292.jpg

Second and third images charts the recoveries of bodies and wreckage on June 6. Top image numbers the wreckage items, but gives no coordinates. Bottom image gives no item numbers, but gives coordinates. I know of only one item that has so far been described as being recovered this day from this area, and that was a seat cushion with a serial number. From an eyeball glance, I believe that if the bodies and wreckage had been where they were on June 6th, these would have been within the Brazilian Air Force search grid for June 1. (Red dots represent a body(ies).

http://i136.photobucket.com/albums/q199/tahitiplage/SNAG-0288.jpg

http://i136.photobucket.com/albums/q199/tahitiplage/SNAG-0314.jpg

The plot of the recoveries on June 7. The VS is marked in yellow.

http://i136.photobucket.com/albums/q199/tahitiplage/SNAG-0322.jpg

June 8.

http://i136.photobucket.com/albums/q199/tahitiplage/SNAG-0320-1.jpg

June 9. (These and all subsequent recoveries are now north of the latitude of Tasil).

http://i136.photobucket.com/albums/q199/tahitiplage/SNAG-0321.jpg

The surface current between June 1 and June 6 centered on 3N and 30.5W, as prepared by the French Ministry of Defense.

http://i136.photobucket.com/albums/q199/tahitiplage/SNAG-0300.jpg

The surface current between May 31 and June 4, centered on June 2
http://i136.photobucket.com/albums/q199/tahitiplage/SNAG-0289-1.jpg

The surface current between June 5 and June 9, centered on June 7 (NOAA/NASA charts).
http://i136.photobucket.com/albums/q199/tahitiplage/SNAG-0291.jpg

All the above charts and plots strongly suggest that AF 447 deviated to the west. How far west and on what heading it flew remains conjecture.

[takata]

SaturnV:
takata, with respect to drift, and possible point of impact, and whether there was a controlled glide or not.
Yes thank you, but, what is the point for reposting that?
It was already posted. The sea surface current maps that you are showing are not detailed enough and possibly build from seasonal averages. The SHOM map is much more usefull and the level of precision 10 times higher than that, and, as you may have noticed, I included it.

Nevertheless, sea surface currents are only a vector of the actual drift and the actual drift is mostly a function of the object drifted which will include plenty of other parameters, including weather. We just don't know them for building a more detailed model including all the wreckages. My point is just a rough estimation and I hope that they will cover this area soon and before the pingers will stop emitting.

[Hyperveloce]

to assess the possible drift of the bodies/debris, shouldn't surface winds (E->W) and even wave trains (SW->NE) be taken into account along with surface currents (SW->NE) being considered here ? knowing the distribution of the recovered debris in space and time, knowing all the history of the metocean data, it should be possible to rewind the movie to the 1st of June with a numerical code to get more accurate results ? typically in the realm of expertise of the IFREMER and the SHOM, and the kind of analysis I expected in the BEA report, the kind of analysis one could make to establish an underwater search area. Now, maybe a numerical code is available or some goodwilling expert in the relevant oceanic lab could help.
Jeff
PS) if it is not the case for all the debris, we know pretty well human bodies characteristics.

[singpilot]

We all forget one additional 'factor' in the sea surface search. The immediate area has every afternoon, evening and night, been subject to massive thunderstorm activity, with rain, localized downdrafts and wave-creating winds impacting the surface. Location of the storms are as variable as the winds they create as they 'migrate' across the region.

[mm43]

Squawk_ident

You got the point.
I knew the mp3 snippet release by the FAB . It's the only official information that TASIL was estimated at 0220. And the controller speaking to Dakar states "Mach 82" But this estimation is not correct at 0.82. It should have been 0211 something like this.I got the point alright, but I inadvertently used an incorrect ETO ORARO.

The BY INTOL 0133z with ETO SALPU 0148 and ETO ORARO 0200z places a new aspect on what took place during the last exchange with ATLANTICO. The following are the extracted distances and speeds from the BEA report on the track of AF447 with auto SATCOM positions. The mean GS through the period of interest was 467KT, which equates to M0.82 at FL350 OAT -46°C.

0130Z
..........78.9NM 473KT
0140Z
..........78.0NM 468KT
0150Z
..........77.4NM 464KT
0200Z
..........77.2NM 463KT
0210Z

Looking at the ETO SALPU & ORARO given at INTOL, the reason for ATLANTICO's request for the TASIL estimate becomes clearer. The reason for no response may be a little more sinister.

INTOL 0133
.................122.5NM 490KT
SALPU 0148
.................122.4NM 612KT
ORARO 0200

ATLANTICO have woken up the the large discrepancy, but for some strange reason did nothing more than call the aircraft 3 times on HF with no reported use of SELCAL.

The ETO SALPU & ORARO should have been -

INTOL 0133
.................122.5NM 467KT
SALPU 0149
.................122.4NM 467KT
ORARO 0204
.................119.4NM 467KT
TASIL 0220 (364.3/467) * 60 = 46.8 minutes.

The question I wish to raise is, "What was happening on the Flight Deck?" On the basis of the established facts there definitely seems to be no known reason why they would come up with estimates that are grossly wrong.

mm43

[takata]

Hyperveloce:
...typically in the realm of expertise of the IFREMER and the SHOM, and the kind of analysis I expected in the BEA report, the kind of analysis one could make to establish an underwater search area. Now, maybe a numerical code is available or some goodwilling expert in the relevant oceanic lab could help.

Hi Jeff,

Sure. But as far as I understand from the interim report. This area of the Ocean was not the most documented of the whole, then the Pourquoi Pas? and the SHOM team was tasked with the mission of filling the many gaps in knowledge.

The first "carroyage" was made by the Navy and, being an ex member of this establishment, I understand it like a "systematic search (very École Navale and Cartesian)" starting from the reference point (0210 last report), and not a SHOM best guess based on sea currents and drifts. Moreover, this matched the most obvious hypothesis: plane crashed at 0214, then no more than 40 NM from 0210.

Now, if the search fails to find the recorders, they will switch to SHOM method in order to locate the wreck and to reduce the perimeter (and cost/time considering the hard work it will be).

S~
Olivier

[surplus1]

To M(F)S and safetypee

Thank you gentlemen for your very informative replys. I now have a much better understanding of what you mean/meant by a “stable stall.” While I would not use that terminology myself it doesn’t matter so long as I comprehend what you intended. I’ll try to address your key points with a single post to both of you. I'm too verbose as it is.

BTW, neither one of you answered my question with respect to the pilot’s ability to deliberately take the aircraft out of Alternate Law and force it into Direct Law if he so desires and I don’t know the answer myself. Although someone posted a fine diagram indicating which protections were retained in Alternate Law and which were lost, I do not recall them exactly. Safetypee you said you believe that stall protection is lost in ALTN Law but what I want to know is: Can the pilot go to Direct Law and remove all “protections” if he chooses to do so? From what I've read, stall protection is lost but stall warning is available from the AOA source.

I ask this question because the entire concept of the automated control system seems to be that it will prevent undesirable positions/attitudes, speeds, etc., as long as we are not in Direct Law. If we carry that concept to its limits - upsets, stalls and overspeeds simply can’t occur – so there is no need to waste time or money training for recovery from them. I do not believe that to be truth.

Every effort and tons of money have been made and spent to keep the Space Shuttle safe yet the vehicle has been lost twice. We build things that we say are ‘fail safe” but nothing is truly fail proof.

While there is nothing at all wrong with fully automated flight control systems per se - they are the wave of the future - if this thread is any indication, there seems to be precious little precise understanding or solid interface between the pilots and the current systems.

As an old timer, I subscribe to Murphy’s Law: “Anything that can go wrong, will go wrong.” While I much appreciate the advances in FCS technology applied to airline transports, we have not reached a level of technology that is “fool proof” and we will not in my lifetime. Systems do malfunction or fail. This is not an Airbus problem nor is it limited to airplanes. It is systemic to all high-tech and low-tech man made systems. If I am correct then, in the case of transport aircraft, I concur with the findings of IFALPA in their June 2009 white paper. If you’re interested, you can read the complete paper here:

About IFALPA (http://www.aeropers.ch/ids/default.asp?URL=http://www.aeropers.ch/ids/file.asp?FileID=378&TopicID=241)

Sorry, I digress; back to stalls.

M(F)S – I basically agree with what you said in your first paragraph, with some qualifications. a) I’m not considering deep stalls of the type that occur in T-tail designs – they don’t apply. b) I’m fairly certain that the A330 is not susceptible to them; otherwise it would have a stick pusher; unless my information is incorrect – it does not. It follows I believe that there is enough elevator authority at all times (where the pilot is controlling the aircraft) to both recover from a stall or to keep the aircraft in a fully stalled state.

The one exception that I see to that would be stabilizer trim, which could so reduce elevator authority as to render it barely useful. [I]I do not envision that as being related to AF447. Reason: the aircraft was in level flight and trimmed for cruise somewhere around M 0.8 or 0.82. - just before the event. I see stabilizer trim as a factor in low speed flight and a scenario in which the AP is holding an altitude or a glide path and A/THR is disengaged and in flight idle. I think that is what you are refering to safetypee re the UK A320 and the 737 AMS accident/incident. If a stall is approached in that mode, when the AP disconnects and power is applied there will be a severe pitch up that the elevator may not have the authority to overcome in a timely manner unless and until the trim is removed by the pilot.

Like you I do not have specific knowledge of A330 aerodynamics at high AOA but I presume them to be quite conventional. Again, this is an airliner, not a fighter, and they all have to meet the same general certification criteria. There will probably be some device(s) to regulate spanwise flow and guarantee that roll control is retained up to and in a stall (even if reduced). Rudder to control skids and slips will also be available if it is not limited by lockout through the limiter and the FCS.

Of course if during an upset the pilot elects to trim or the automatic trim continues to function and to input trim change, it could indeed be possible to create a situation where there is not enough elevator authority to prevent a stall, or on the other side to effect a recovery from a dive. I doubt that’s a factor in this accident. Since I don’t know how much artificial feel is present in the A330 I can’t guess as to whether the pilot would decide to trim during and upset. I also don’t know at what point automatic trim stops functioning. Is it available without the AP?

Now we come to the meat and potatoes of your “stable stall” theory.

If the pilot is intentionally stalling the aircraft he will be hand flying, not the AP – speed will be reduced with back pressure at a steady rate, in flight idle, until buffet ensues or the shaker activates. If he then wishes to reach a full stall he will continue to increase back pressure until it happens. At that point, under normal conditions, the nose will drop.

The pilot can continue to apply full back pressure and the wing will remain stalled. A high sink rate will ensue and AOA will increase further. However, when the pilot runs out of back pressure (as the speed and elevator effectiveness decay),, the nose will drop again and the aircraft will begin to oscillate in pitch. [Whether side stick or yoke, there is only so much physical movement available – and only so much elevator authority.By design that is not normally allowed to exceed required inherent stability] Aircraft designs change but the laws of Physics do not. In the transport category (as in others) there are established requirements that have to be met. I am quite sure that all ABI transports meet or exceed those requirements. At this point in time what you define as a “stable stall” will end. When I say that the nose will “drop” that does not necessarily mean that it will go below the horizon (although it probably will). It does mean that the body angle or pitch attitude will decrease significantly.

During these oscillations one wing will certainly become more stalled that the other in short order and the aircraft will begin to roll in the direction of the wing that is more stalled. When up aileron/spoiler is applied on the high wing there will be a degree of yaw, which will tend to induce rotation. If this continues roll/bank angles will get progressively higher with each oscillation and the pilot will always be just a little behind the aircraft [he can’t really anticipate control inputs – he merely reacts to attitude changes that are already in progress.] Eventually he will be using full aileron back and forth and bank angles are quite likely to exceed 90 degrees eventually. He will also be using whatever rudder is available and will also be behind in its application. If there is enough altitude available and the pilot never releases the back pressure, the aircraft will enter a spin. If full rudder is available and used, it is highly probable that the VS may fail before the normal spin occurs [side loads will get pretty high with continual erratic control inputs]. If that happens the spin is likely to be “flat” since the VS is the only thing that is preventing rotation about the cg. Should the fin fail, one or more engines will most probably leave the airframe – due to severe yaw.

This url will take you to a scenario that occurred in a DC8-63. It demonstrates what I have said. They didn’t start with enough altitude to actually spin.

http://www.apstraining.com/article9_fci_training_aug03.htm (http://<a href=)

It is my belief that in line operations – no pilot is going to intentionally stall his aircraft - or if it stalls accidently attempt to keep it in what you call a “stable stall”. The stall will very rapidly become “unstable” in the extreme in any case.

In my opinion, this negates the idea that AF447 could have descended 35,000 ft in a prolonged wings level – body level – flight attitude – with a vertical trajectory - still in one piece. I just can’t buy that. If my analysis is even close to correct and the aircraft did descend – wings level body level – until impact, something else had to make that happen.

Whatever happened to them [that caused the upset] happened very fast and didn’t last very long before things were completely out of control. Most probably seconds – at best a few minutes.

At this point I don’t buy the idea that the anomalies reflected in the ACARS messages were the cause of a sudden upset. If they did cause a complete and prolonged loss of control at all, the aircraft would likely have descended in a steep spiral at very high speed or a normal spin –stalled but at relatively low speed. Either one of those would seem to preclude contact with the ocean in a “level flight attitude” or anything close to it. However, a ‘flat spin’ could produce a “level” impact of the remaining structure. I don’t believe the a/c would flat spin unless there was some structural failure at altitude. That’s not fact, it is just my opinion.

At their altitude they were not very much above the stall speed for starters, and not much below overspeed either. If they got the shaker it is quite probable that they would have added power if they could. How much is only a guess. Intense vertical gusts could prevent that. An extreme up draft could have rapidly produced an altitude increase of severl thousand feet - placing the aircraft outside of the envelope. Follow that with an equally violent downdraft and repeat the sequence several times. I'll leave the "g" to your imagination - but I respectfully submit they are going to be way in excess of +2.5 or -1.5.

If they got a high speed warning they most probably would have reduced power. With normal law – AP and A/THR engaged, if I understand correctly, those things would have happened automatically as the FCS tried to keep the aircraft within the flight envelope. The aircraft would not have stalled or experienced an overspeed – if all of that worked as intended. For what ever reason the automatic stuff wasn’t playing by the rules that night.

Extreme turbulence would most probably exceed by far the limits of the AP – causing it to disconnect. IMO, it could also exceed the parameters of the automated FCS – which would probably trigger multiple failure modes and warnings. I don't know that but it seems logical.

Everything has its parameters and limits. When uncontrollable forces exceed those limits by wide margins, things begin to fail.

I’m not suggesting that there is anything wrong with its design – I am suggesting that whatever happened very rapidly exceeded its limits. In the process multiple errors and failures occurred – triggering the automated messages. In other words I am suggesting that the system went berserk after something extreme and unusual happened to the aircraft – not before it did.

As soon as the ACARS messages were leaked everyone began to focus on the messages and to assume that whatever their meaning (we now know pretty much) they must have been the [I]cause of what ever happened to AF447 – the trigger. Most of us remembered the Qantas and Air Caraibes incidents and looked for ways to make the messages fit the cause of the accident. I was on that bandwagon as well.

Then I looked at the excellent wx analysis of Mr. Vasquez a few more times and began to wonder. I’ve flown in that part of the world. Back then we didn’t have satellites to show us pretty pictures. We had radar in the airplane but it wasn’t in living color, and yes, my airplane was the badest jet in town at the time. I had a 3-man cockpit crew – all very experienced.

Well, one dark night I inadvertently flew my airplane into a cloud. We knew the weather would be bumpy, it always was on that route, but we didn’t expect what happened next and we never saw it on the tube. There was no lightning in our immediate vicinity. It was at night and very dark outside. The canary flew into the fan and the result was feathers everywhere all at once. It got my attention and I will never forget that experience. I’m sure there are others on this forum with similar experiences. That is why old timers are afraid of Cb’s.

We didn’t upset or lose control but at times that really wasn’t because of anything that we did. I couldn’t begin to tell you how we managed to keep it right side up for the truth is the airplane went wherever it wanted to go, whenever it felt like it, and there was nothing we could do about it. Altitude gains and losses were not hundreds of feet, they were thousands of feet. The violence was more than I’d ever thought could exist. Most instruments were unreadable due to the vibrations but we didn’t lose the old steam gauges, they just weren’t very useful at all. We never even tried to change the power since it was already set for turbulence penetration – if we had wanted to I doubt we could have since keeping a hand on the throttles would have been virtually impossible. We just hung on for dear life and had our individual conversations with the Great Spirit. Somehow the airplane managed to make it through. The entire experience was only about 4 minutes long but it seemed like eternity (no pun intended). Since I’m writing this you know the airplane stayed in one piece but I have no idea how that happened. Were we scared? Yeah, you could say that; never more before or since. I vowed I would do anything to avoid a repeat of that experience. And you know what - It never did happen again. By coincidence we were over Brasil at the time, in cruise, on the way to Sao Paulo. In the future I got yelled at a couple of times for what the “suits” called ‘unnecessary diversions’ but you know what – my kids still had a dad.

If the crew inadvertently flew into a deadly cell it does not mean that they were negligent and it does not mean that they were not deviating for the weather they could see. Sometimes those things just happen.

With respect to the BEA report I have some opinions too. First of all it is a Preliminary Report, nothing more. There are lots of “interested parties” on those Boards and they are not going to agree to any “release” that might be interpreted as putting them in a ‘bad light’ when the evidence is not definitive. They will seek to include anything they can that would reduce their individual exposure.

A “break up” in flight would not be a good omen for ABI. It would reflect adversely on AF’ operational controls, it might be adverse to the flight crew and imply pilot error. Each of those “interests” will protect its own. The last thing they need is images of parts coming off the airplane in flight questioning its structural integrity or suggesting pilot error (the union won’t sit still for that).

That does not speak ill of the BEA or any of those entities. It happens everywhere. Boeing will fight tooth and nail to eliminate anything in a report that might adversely reflect on its designs. Remember what they did re: the rudder hard-overs in the 737? It took many dentists and more than one fatal accident to get them to finally admit to a flaw in the rudder PCU. Anything that suggests that the automatic systems of the ABI design failed or were unable to do their job will be resisted until there is no way out. Find a reason for that floating VS – doesn’t matter what it is – as long as you don’t imply that it may have come off in flight. That’s all very natural. The Board came up with a reason. It’s only preliminary and they can change it later if necessary. Don't read too much into a Preliminary Report.

But, somebody tell me how you can determine the failure mode of the VS by examining photos? How do you know the entire tail didn’t come off? You can’t – it will take long-term, in-depth engineering analysis and maybe even recovery of the tail section (very unlikely). They didn’t have that when they issued the Preliminary Report, just as they didn’t have the full pathology on the recovered victims of the tragedy. Those things take time – but in 24/7 hungry media you have to say something, so they did.

As the investigation proceeds, interested parties will continue to protect their interests to the extent possible. They always do in all investigations. If the recorders are recovered there will be hard evidence and the truth will eventually come out for the most part. That is how the process works and we will just have to wait. It may well take a couple years or more before we have a final report. The media frenzy will have long ended and they’ll put it on page 16 – if the bother to publish it at all. The public span of attention is very narrow.

We don’t know what happened gentlemen – but do not rule out a sudden encounter with extreme turbulence. The forces of nature are far greater than those of men and they are NOT fully predictable. There is nothing that we put together that nature is incapable of disassembling – in any variety of modes or parts.

[takata]

singpilot:
We all forget one additional 'factor' in the sea surface search. The immediate area has every afternoon, evening and night, been subject to massive thunderstorm activity, with rain, localized downdrafts and wave-creating winds impacting the surface. Location of the storms are as variable as the winds they create as they 'migrate' across the regionYes, you are right. But as far as I know, the 6-10 period had afternoons, evenings and nights also, with rain, etc. and the final drift was almost straight North for 4 days. The weather, winds, thermoclyne, salinity, density, temperature, pression is not varying all together in one day. It takes several and, as you may notice from the ITCZ, the wheather phenomenons are very cyclical and almost always at the same place.

All this for saying that it is very improbable that the drift was North one day, South the following day, East, the day after and so on...

S~
Olivier

[Brenoch]

Surplus1;

Excellent post

[cws]

Hi Gentlemen,
I flew three hours behind the AF on that day and never even heared one blip on 121.5. My question as a non Airbuspilot, isnt there a elt installed that radiates on impact/certain g-loads? If so, Boeing A/C have them, at least a few ELT Blips should have been heared/picked up by me and other A/C in the vicinity. Can you shed some light on this?
Many thanks,

[takata]

cws:
I flew three hours behind the AF on that day and never even heared one blip on 121.5. My question as a non Airbuspilot, isnt there a elt installed that radiates on impact/certain g-loads? If so, Boeing A/C have them, at least a few ELT Blips should have been heared/picked up by me and other A/C in the vicinity. Can you shed some light on this?
Hi,
Did you read in the interim report that they have recovered one AF447's ELT intact?...It was off.
They got three on board, and I guess, at least two in the cockpit with other survival equipment, but they are not automaticaly emitting "on impact". They have to be switched ON manualy. Are you sure yours are automaticaly working in this case?

S~
Olivier

[Hyperveloce]

Now, if the search fails to find the recorders, they will switch to SHOM method in order to locate the wreck and to reduce the perimeter (and cost/time considering the hard work it will be).


Given the large area already searched, I have come to think that if there was an acoustic source to be detected or detectable, It would have been detected. I hope I am wrong. About the drifting:
Drifters in area of crash of Air France flight # 447 (http://www.aoml.noaa.gov/phod/graphics/dacdata/Air_France_drifters.html)
The Global Drifter Program - Information (http://www.aoml.noaa.gov/phod/dac/gdp_information.html)
Jeff

[ClippedCub]

The Amsterdam recent incident crashed much like that landing flat but with a high sink rate. If they were in a spiral dive and saw the ocean coming towards them in the final seconds they would attempt to pull out wings level but if they couldn't they might hit flat or even nose up with a very high sink rate at impact.

The Amsterdam airplane was configured for landing. Recovering from a spiral dive before impact would imply a high speed impact.

I’m fairly certain that the A330 is not susceptible to them; otherwise it would have a stick pusher

The DC8 example is applicable, but the A300 incident I posted a few pages back is closer to the 447 configuration. The roll reversals in the DC8 report can be thought of as partial snap rolls, and are useful in determining the configuration's ability to spin.

The A330 was certified with FBW and if I understand other posters, doesn't require stick pusher because of that. The FAA wouldn't require stall protection after multiple failures and degradation for FBW status. The A330 in baseline configuration will not enter a stable stall without gyroscopic forces for stabilization. Not to say the HS didn't depart or any of a number of other things to change the airplane from baseline. The aft CG at cruise could be enough for a spin to go flat and if that's the case, then it's unlikely the HS would be enough to overcome the condition. The VS would be blanketed by the HS, i.e., lack of rudder area below the HS, and would be useless for upright spin recovery.

[cws]

@Takata
Hi, thank you for your reply, I read it but could not really comprehend it completely since I am not familiar with airbus. We have also two mobile elt which have to be manually activated but the third one is build in and is in the position armed at all times in flight, meaning it will start once a certain g-force was applied, happened even on some really hard landings...
That was the reason I was asking. I did not know that the Airbus has only mobile ELTs and no stationary built in ELT. In Boeing A/C the ELT has a own switch on the overhead panel with a three position switch on, off and armed, armed position being guarded.
Greetings

[takata]

cws:
Hi, thank you for your reply, I read it but could not really comprehend it completely since I am not familiar with airbus. We have also two mobile elt which have to be manually activated but the third one is build in and is in the position armed at all times in flight, meaning it will start once a certain g-force was applied, happened even on some really hard landings...
All right, so maybe I'm not very well informed about this and maybe PJ2 could answer this question about build-in beacon. All I know is that Air France contacted the Satellite SAR provider and they found no trace of activated beacons. If they had one build-in, it didn't turn on.
I was previously talking about the mobile ones, and it is the same as yours, two are locked in overhead panel with survival equipment in case of ditching.

S~
Olivier

[takata]

@ Hyperveloce:
Thanks for this link. I checked all this buoys before, too bad that none were drifting at the right place and, as you can see here and even on the SHOM map, this area drift is fairly different North, South, East & West from this place!
On the other hand, the drift is mostly continuous in direction for days (but not the speed) with slight variations until the reversal zone above 5N which is showing erratic and spiral drift. I'm still hoping they will be able to find the wreck soon. The deep sea relief is the main obstacle as they have to use towed sensors listening very close to the bottom.
S~
Olivier

[JD-EE]

einhverfr, way back someone posted structural drawings (or links to images of them) of the internal structure of the tail section below the VS including the very end of the pressurized section. By all appearances the tail section is flimsy compared to the rest of the plane. I'm not trying to say it was too weak to do its job. It appears just quite weak relative to the rest of the plane.

As you note the VS is attached to it securely enough but not with structural steel girders. This suggests the tail assembly is a little stronger near the pressurized section than the rear.

Suppose the rear hits first or at least in such a way that the tip of the tail is pushed upwards relative to its normal position. The nose is still pretty much unmoved. The raised tail damages the rudder and pries the VS off the rest of the tail section.

The concept of the tail hitting slightly before the rest may not be needed. But it helps visualize the process. The action of the elevators would help lever the rest of the plane into its appearance of nearly flat encounter with the water. It might also serve to further lever the VS away from the rest of the tail assembly after the middle portion was torn away from the initial tail cone collapse.

JD-EE

[Graybeard]

That's been my visualization, too, JD.

It accounts for the compression damage to the bottom of the rudder and little other impact damage.

[JD-EE]

ARFOR, as a non-pilot that summary looks good. One thing to consider, as an EE who digs RF communications and antennas, is that as long as the plane was nearly horizontal, within 20 degrees or so, more ACARS messages COULD go out if they were generated. That coupled with the high vertical speed component to its encounter with the water in normal flight orientation suggests to me that the flight of AF447 may have ended somewhere depressingly close to the last message at 0214.

(I am (rashly?) presuming that the damage encountered is consistent with the plane hitting with the wings nearly level, at the very least. As soon as one digs in the leverage should produce a distinctive damage profile. I am not sure we can say nose or tail first or purely horizontal, though. My guess, as a preceding message indicates, is that the VS was levered off the plane by the collapsing tail cone from a slightly tail first encounter with the water.)

JD-EE

[SaturnV]

takata, there is one problem with your analysis of the SHOM chart (I assume you are referring to the chart in post 3138) and the initial northward drift of bodies and wreckage that you calculated occurred between June 1 and 5. This drift lies within an area that was repeatedly overflown and searched by the Brazilian Air Force over this period, and nothing was recovered belonging to the plane.

Here are the cumulative search grids by the Brazilian Air Force June1-5:

http://i136.photobucket.com/albums/q199/tahitiplage/SNAG-0297.jpg

Note, the circle in the image above does not denote a search grid, only a radius for a subsequent search focus once bodies and wreckage were discovered on June 6.

It is no accident that the search for the FDR and CDR extends west 65 NM from the last position report, and south for only 40 NM from that position. (40 NM being the standard minimum radius for all quadrants in the search grid.)

I agree that surface winds can alter the direction and speed of objects being carried by surface ocean currents. The SIGMETS issued for this area on May 31 - June 1 describe the CBs as stationary. As I read the detailed French meteorology report, a similar pattern of CB complexes occurred daily between May 30 and June 3 over this general area.

Sur la période de quatre jours du 30 mai au 3 juin 2009, l’évolution des zones nuageuses observées est typique de ce qui est fréquemment observé dans la ZCIT, qui s’étend sur une largeur moyenne de l’ordre de 500 km

[takata]

SaturnV:
takata, there is one problem with your analysis of the SHOM chart (I assume you are referring to the chart in post 3138) and the initial northward drift of bodies and wreckage that you calculated occurred between June 1 and 5. This drift lies within an area that was repeatedly overflown and searched by the Brazilian Air Force over this period, and nothing was recovered belonging to the plane.Right. But what those maps are showing is the theoretical search considering the SAR flight plans for the aircraft involved and their theoretical range of detection.

It doesn't picture in any way how many times they flew above each area, what the aircraft crews actually were able to spot/detect because of the bad weather, luminosity, and plenty of other parameters. But maybe you are not very familiar with this kind of operation and it is pretty hard to see something fairly immersed like aircraft wreckage (or victims) when flyng at 200 kts above the sea for very long hours. A good example of the difficulty is when they tried to relocate some wreckage they spoted the day before without success during several days. Certainly, they would not have missed embarcations with survivors, but the wreckage... this is another story.

(Moreover, the SHOM map for the 5th is clearly pointing a very eastern surface current at the location where the bodies were recovered June 6, but their actual drift was still full North for 5 consecutive days...)

S~
Olivier

[westcoastflyer]

how does AF follow up on the computer flight plan?
they are highly accurate and by comparing their FP times with the FMS times ,speed errors of such a magnitude should have become apparent to the crew,not needing Atlantico to realize it.

[safetypee]

surplus1, re #3147.
AFAIK there is no ‘big switch’ enabling the pilot to select Direct Law. However, it appears that the law could be invoked by selecting off an appropriate selection of sensors (e.g. IRS) or flight control computers, but I don’t know the exact details.

Undesirable flight states; stall appears to be prevented in Alternate law (ALTN 1) by the low speed protection, IAS replaces the AOA function, but in this accident it appears that there was no IAS. AFAIK this gives ALTN 2 law – no speed protections; I don't know about any alerts.

The architecture of the A330 control system provides an adequate level of ‘fail safe’ for aviation, as defined by aviation requirements – based on experience. In this sense Airbus wasn’t the first to test these regulations as there were many test aircraft and military experience beforehand.
Many people appear to have overlooked the point that when the A330 is flown direct law it is essentially the same as the older generation aircraft excepting that, like them on occasions, you might lose VMO/MMO and Stall warnings, and if applicable stick push; in which case you took extra care at low speed.
The one significant difference that I am pursuing is the trim operation. In direct law it is via the hand wheel – the old way, but in ALT law the trim operation appears to be in some quasi state attempting to operate normally (auto-trim / follow-up trim), but not associated with the of the loss of protections, and thus may be ‘auto’ active in a stall. Furthermore, the crew may unaware of this (isolated from trim activity).

Re pilot interface with automation; one of the major issues is the crew’s understanding of the differences in the levels of automation – what are the crew responsible for and when, and then relating these states to a previous or clearly understandable method of operation; but rule 1 still applies – fly the aircraft.

I agree that nothing should be ruled out or in. We all appear to have crossed the bounding rules. The search for understanding is perhaps better achieved by questioning, opposed to statements of ‘fact’ seen elsewhere in this thread.

[JD-EE]

At 420 knots the plane is going 7 miles a minute.

At 0210 we have a position. Presuming the plane was still aimed "roughly" along the planned flightpath and presuming perhaps some pushes by storm winds where could the plane have gotten to by 0214 plus maybe a little Kentucky Windage for surviving a bit past 0214?

"Where could the plane possibly be?" might be a better search criterion than "where do the currents extrapolate backwards to at the time of the crash?"

And, of course, I am fastened on to the apparent fact that the plane was either deceased or was no longer even approximately horizontal after 0214.
Aiming of the satellite antenna is somewhere between a TV yagi on a rotator and a pair of rabbit ears in a high signal area for reference. You can be a whole lot off and it still works. Plus or minus maybe 60 degrees of vertical for a 3dB (half power) loss. Within about 35 degrees you'd have trouble picking the optimum direction without automation.

This is why "what is the region it could have reached in 5 minutes or less is my search criterion. Then match that with the currents to try to refine it all. And I have an untutored hunch that turning an A330 or anything else at FL350 is not "sharp" by any stretch of the imagination unless you are purposely entering a dive as for a bombing run.

JD-EE

[singpilot]

Remember, the 0214 time is the last received time for any datalink from AF447. Reversion to anything other than 'Normal AC Power' would have turned the ACARS system off. The plane could have been airbourne for some time after that, expanding the search area requirements.

[UNCTUOUS]

Surplus1 said
If a stall is approached in that mode, when the AP disconnects and power is applied there will be a severe pitch up that the elevator may not have the authority to overcome in a timely manner unless (and until) the trim is removed by the pilot.
Undesirable flight states; stall appears to be prevented in Alternate law (ALTN 1) by the low speed protection, IAS replaces the AOA function, but in this accident it appears that there was no valid IAS. AFAIK this gives ALTN 2 law – no speed protections;
I accept what surplus1 says about a maintained stable stall being unlikely, however his arguments don’t apply to a spin scenario. Once entered and stabilized (for whatever reason), some aircraft will remain in a sustained stick-free spin until impact. It’s the nature of the beast and a function of the momentum built up by the couples in autorotation (hence the “auto”). The most recent precedent is the TU154 crash in Donetsk. It was a very similar situation except that the pilots had attempted to outclimb the storm clouds – rather than suffered an autopilot disconnect and pitch-up. They rode it down, attempting recovery, and even managed to punch out a distress call or two.

However I don’t believe that the aerodynamic forces in play at spin entry (or during a spin) would’ve been anywhere near that required to generate fin failure/detachment. The four minutes of ACARS messages stemming from that initial failure would have started at autopilot “kick-out”.

So if we now apply Occam's Razor and then summarize:

Can't rule out pilot incapacitation yet but it's more likely that the two copilots were minding the shop and were caught out when the autopilot suddenly kicked out and they faced a severely out-of-trim aircraft pitching up into a stall/spin situation (thanks to the faulty pitot tubes and auto-trim and a confounded ADIRS).

If the auto-trim progressively wound in lots of back-trim as a result of the pitot supplying increasingly false air-data, the A330 may not have been recoverable in Alternate Law (which they were suddenly in). It's one of the unattractive aspects of a trimmable horizontal stabilizer and an autopilot that's capable of holding large out-of-trim loads.

One big fallacy is that you cannot stall a FBW Airbus. That law is trumped by a dynamic pitch-up into the tenuous aerodynamics of coffin corner flight. i.e. to say that no further pro-spin flight control inputs are required. Thanks to the high nose attitude and the couples, the stall/spin scenario is the only logical aerodynamic outcome (with or without an engine hiccup). That's what can happen in a thin air regime that pilots very very rarely fly manually in. And you can reflect upon the likelihood that such corners of the operating envelope would never have been pursued by Airbus test-pilots. Engines that are suddenly exposed to a high AoA at high power in coffin corner are also likely to stall (due intake blanking). One engine stalling would have provided the asymmetry for rapid instantaneous entry into a flat spin.

Why could it have remained a flat spin? As the aircraft descended and the air thickened, the engine would have unstalled itself (that's what happens with N over root T stalls), provided high symmetric thrust and kept the spin flattened. Distracted pilots may not have noted that the auto-thrust had also dropped out and that the throttle positions were now dictating thrust directly (after all, during a developed spin there's lots of centrifugal force and the pilots were probably not able to focus on the ECAM). They'd have been trying stick and rudder inputs for recovery. The nature of a flat spin is that recovery via unsustained flight control inputs is highly unlikely and, because of that high centrifugal force, anything not tied down in the cabin or holds would've migrated aft, further exacerbating the aft CofG complication for a flat spin.

The nature of spins generically is that the correct flight control anti-spin inputs must be made AND HELD to be ultimately effective in recovery. CRM just doesn't operate in a terminal spin - and in a FBW Airbus there's got to be a formal hand-over/take-over and a pressing of side-stick buttons, or control inputs are either negated or reinforced. The galvanic nature of a spin is not conducive to two pilots caught by surprise, agreeing on the correct throttle and stick/rudder positions and holding them static - at least not long enough for their inputs to overcome the spin's considerable inertia. Coherent analysis, communication and trouble-shooting is just not possible in a full-blown spin. AF447 has likely been one of those "points of no return" developments that lurk beyond aviation's rarely visited thresholds.

A sudden lunge into the deep recesses of coffin corner, courtesy of the triple ADIRUs finally rejecting erroneous pitot-derived data - and reacting and rejecting- is to swiftly and unexpectedly cross one of those thresholds. When examining the hazards of a known deficiency, and the urgency of any need to correct it, both EADS and the FAA should be looking at the possible complications arising at (or just outside) the edge of the operating envelope - and extrapolate from there.
.

[takata]

JD-EE:
At 420 knots the plane is going 7 miles a minute.At 468 knots (Mach 0.82) and FL350, the plane is going 7.8 miles a minute, and this was F-GZCP configuration at 0210.

At 0210 we have a position. Presuming the plane was still aimed "roughly" along the planned flightpath and presuming perhaps some pushes by storm winds where could the plane have gotten to by 0214 plus maybe a little Kentucky Windage for surviving a bit past 0214?Why would the plane be only "roughly" aimed along the planned flight path at 0210? By all calculations possible about her position, she was maybe slightly deviating 3 NM to the West, but not much. The "pushes from storm wind" is something you know for sure or is it your imagination?

This hard flying condition are not documented anywhere and all we can verify by sattelite IR imagery is that she was pretty close to the coldest part of the convective CB cells around her, but we are left without a single clue about how bad or good the real situation was. LH507 crossed 20 mn before with a 10 NM deviation West and reported only moderate turbulences. There is a strong evidence by F-GZCP thrust setting that she was not in severe turbulences at 0210. Please, give a little credit to the pilots and consider first that they will do what they were supposed to do, weather avoidance and turbulence procedures, until we got something like a hard proof that they failed to do so. The next Air France flight, 37 mn later, deviated 80 NM as it is not in the company policy to fly strait into bad weather for saving fuel. If they picked this way, it would have been painted safe (right or wrong) on their radar and they are supposed to have been trained well enough to use it, or we need evidence they were not.

"Where could the plane possibly be?" might be a better search criterion than "where do the currents extrapolate backwards to at the time of the crash?"
And, of course, I am fastened on to the apparent fact that the plane was either deceased or was no longer even approximately horizontal after 0214.Again, it is mostly your imagination: what clue do we have for considering the aircraft 'deceased' at 0214? Unreliable air speed indications? Is it enough without adding a little bit more imagination: updraft, downdraft, storms, lightnings, stall, spin, spiral, dive, upsets, tailfin wiped out, computer glitches... crash?
All the facts we know for sure about the real weather situation is resumed in one word: ice. How we know it? The ACARS are telling us that the probes are freezing, that's all and we should stick with it as the primary weather issue encountered.

Aiming of the satellite antenna is somewhere between a TV yagi on a rotator and a pair of rabbit ears in a high signal area for reference. You can be a whole lot off and it still works. Plus or minus maybe 60 degrees of vertical for a 3dB (half power) loss. Within about 35 degrees you'd have trouble picking the optimum direction without automation.

This is why "what is the region it could have reached in 5 minutes or less is my search criterion. Then match that with the currents to try to refine it all. And I have an untutored hunch that turning an A330 or anything else at FL350 is not "sharp" by any stretch of the imagination unless you are purposely entering a dive as for a bombing run.Then, all your 'search criterion' are mostly based on... imagination, but not on verified facts. Here is a relevant example where, if this incident would have ended in catastrophe a few miles before the runaway, without any communications and radar coverage, your imagination would have placed the crash site 85 nautical miles off the coast. This flight would have ceased to transmit any ACARS at 0626 @ FL345, after sending an engine failure at 0613 and when flying at FL390:

Air Transat Flight TS236, was en route at FL390 when at 05:36 UTC, the crew became aware of a fuel imbalance between the left and right-wing main fuel tanks. Five minutes later the crew concerned about the lower-that-expected fuel quantity indication, decided to divert to Lajes Airport in the Azores. At 05:48 UTC, when the crew ascertained that a fuel leak could be the reason for the possible fuel loss, an emergency was declared to Santa Maria Oceanic Control. At 06:13, at a calculated distance of 135 miles from Lajes, the right engine (Rolls-Royce Trent 772B) flamed out. At 06:26, when the aircraft was about 85 nm from Lajes and at an altitude of about FL345, the left engine flamed out. At 06:39 the aircraft was at 13,000 feet and 8 miles from the threshold of runway 33. An engines-out visual approach was carried out and the aircraft landed on runway 33. Eight of the plane's ten tyres burst during the landing.
Investigation has determined that a low-pressure fuel line on the right engine, had failed probably as the result of its coming into contact with an adjacent hydraulic line.

S~
Olivier

[ttcse]

I do enjoy reading what you big plane flyers write.

The nature of a flat spin is that recovery via unsustained flight control inputs is highly unlikely and, because of that high centrifugal force, anything not tied down in the cabin or holds would've migrated aft, further exacerbating the aft CofG complication for a flat spin. On this particular point, I do believe that it's a standard spin where the centrifugal forces would migrate everything aft. In a flat-spin they go to the nearest extremity, what's in the cockpit gets forced forward.

takataAgain, it is mostly your imagination: what clue do we have for considering the aircraft 'deceased' at 0214? On this point I'm with JD given: the preliminary report of essentially vertical impact on the belly, the projected positions at 0214 being in the neighborhood of the initial debris finds, and the most likely reason a satellite connection was lost. They tend to pair up. All other possibilities get more complex.

[auraflyer]

I think that some information that can be gathered from the raw BEA data might put paid to some of the speculation, especially if viewed chronologically. Here's my amateur attempt. There may well be errors in what follows (especially towards the end when I got tired), and I'm happy to be corrected.

Position

If we look at the BEA report, we see that the aircraft was transmitting AOC position messages approximately every ten minutes, as it was set to do (sec 1.6.8 and 1.16.2.2).

The map on page 11 has plots of positions at 00:29, 00:39, 00:50, 1:00, 1:10, 1:20, 1:30, 1:40, 1:50, 2:00 and 2:10. I assume these are all taken from those messages. Nothing thereafter.

The transmission sequence at 1.16.2.4 (p 46) shows the position according to the message for 2:10, which was received at 2:10:34. That was about 24 secs after the first relevant ACARS message (AP off) was received.

Let's examine the lead up to this.

Radio and ATC

The last successful radio conversation was with Brazilian ATC at 1:35:43 (sec 1.9.1). At this point, the aircraft was at the "edge of radar range of the Brazilian control centres" (findings, p 68).

At 1:35:15, AF447 contacted Atlantico. (fwiw, transcript is: "AIR FRANCE FOUR FOUR SEVEN, by checking INTOL zero one three three, level three five zero, SALPU zero one four eight, next ORARO zero two zero zero, selcall check Charlie Papa Hotel Quebec." (annexure 3 p 99))

They thanked the controller at 1:35:43, but did not respond to requests made by him from 1:35:46 to 1:36:14.

Hypothesis 1: The crew passed from radio coverage with Brazil at this point, all still being in order.

AF447 made 3 attempts to connect to Dakar ADS-C: at 1:33, 1:35 and 2:01. These were rejected because of a flight plan absence or mismatch (sec 1.16.2.1).

The conversation with ATLANTICO seemed to follow the first rejection attempt: the crew contacted ATLANTICO at 1:33:25 (sec 1.9.1; annexure 3 p 99). [I'm assuming all times in the report have been synchronised - see sec 1.15].

At this point they said they were at FL350 (as cleared).

Hypothesis 2: The crew was working normally at all three rejected connection attempts, as nothing was mentioned at 1:35, and I assume they would not have attempted to connect the third time if an emergency had already arisen. If correct, this suggests that they tried to connect to Dakar ADS-C about the time radio would be lost with Brazil, then contacted Atlantico presumably when they could not get on. They then tried to connect again around about the time they finished talking, and again 25 mins later.

Hypothesis 3: We know that there was never any radio contact between AF447 and Dakar (sec 1.9.2). In addition to ADS being rejected, the crew was simply unable to establish radio contact with Dakar. This was consistent with the experience of IB6024 ("difficulties") and AF459 (contact established around 3:45) (sec 1.18.3). LH507 (20 mins ahead) reports hearing nothing from AF447 on 121.5 throughout the flight: 1.18.3.

Observation 1: We are not told if anyone has attempted to identify who from AF447 was talking at that point - could put to rest some of the speculation about who was where on the flight deck.

Weather

At 2:01, based on the map at the bottom of p 30, the aircraft would have been very close to the southern edge of the CB activity. [Assuming for this purpose that the data in the title bar correctly shows that this was the plot for 2:00. Query extent of any averaging with earlier data done to produce this image.]

At 2:07, there is an image of the weather, apparently as at this instant: see sec 2.2.2 of annexure 1 (French report). [It refers to "l’image prise à 2 h 07", ie "the image taken at 2:07"].

If we estimate the position of the aircraft as 70% of the way between its position at 2:00 and 2:10, and align it over the image at sec 2.2.2 of annexure 1, we are into bad weather. The aircraft appears to be within the area of -70C, shown in figures 9 and 10 (which only show the position of the aircraft at 2:10), but not yet into the -75C weather shown in Figure 11.

By 2:10, the aircraft has either just touched on, or is just leaving, the area of -75C in Figure 11, assuming that area remains about the same within the 3 minutes since the image was taken. That is about the time (within 24 sec) of the first ACARS messages - ie AP disconnect -- and about the time of loss of windshear reaction, alternate law, autothrottle off, TCAS fault, rudder travel limit warning (p 49).

Note that these all occurred in a cascade at 2:10, even though some were not received until later: see the sequence at p 49.

Also note: "ECAM messages are transmitted in real time as soon as they are acquired. Flag or advisory messages are transmitted as soon as they have been confirmed. Fault messages are transmitted as soon as the corresponding correlation window is closed." (p 25)

Third note: There is an assumption that the position transmitted for 2:10 (+2.98, -30.59) is actually correct - see sec 1.16.2.2: "The position transmitted was the aircraft’s FM position which, in normal conditions, is close to the GPS position." I haven't seen this commented on, but it means we should keep in mind the possibility that the actual position could have differed, if something had already gone wrong.

At 2:11, we have a sequence of ACARs messages received, showing that the ACARS system was still connected.

Hypothesis 4: The aircraft did not move more than 90 degrees in any direction from normal flight up to 2:13:14, as this would have put the antenna out of contact with the satellite (I assume a 180 hemispherical envelope).

At 2:12:51, the "ADR disagree" message is received at base. The time *logged* is 2:12, so it appears that no more messages are banked up at this point. [Note: I may be wrong, my understanding of ACARS is very imperfect]

Between 2:13:14 and 2:13:45, ACARS communication is lost, for whole or part of the period; "the gap observed between the message sent at 2 h 13 min 14 s and the one sent at 2 h 13 min 45 s is due, at least in part, to a temporary interruption in the communication link between the aircraft and the satellite" (1.16.2.4, p 47)

Some time at 2:13, we have the Prim 1 and Sec 1 faults logged. They are received at 2:13:45 and 2:13:51 respectively. We also have the "FMGEC1 (1CA1) (2 h 13)" message, which "has not been fully explained at this stage of the investigation. The fact that it was “INTERMITTENT” means that the fault was detected for less than 2.5 seconds" (p 54). This is received at 2:14:20.

Some time between 2:14:00 and 2:14:14, the "maintenance status ADR2" is logged, and then received at 2:14:14. Some time between 2:14:00 and 2:14:26, the cabin vertical speed advisory is logged, and received at 2:14:26.

The last signal successfully received by the aircraft was transmitted at 2 h 14 min 28 s: page 47.

ACARS & Questions

It is at this point that data runs out, and it is not prudent to go any further without answers on known-good information.

According to PJ2, ACARS uses VHF if possible, otherwise Satcom [post 791, http://www.pprune.org/rumours-news/375937-air-france-a330-200-missing-40.html#post4972795 ]. The BEA report states that all were sent by SatCom. Corollary: no VHF, consistent with no comms to Dakar.

ACARS is also powered by the AC1 bus.

Question 1: to what backup level is ACARS powered. Say we lose AC1. Does ACARS lose power & ability to transmit? If not, at what point does it lose power? Cessation at 2:14 might only signal loss of power up to the point at which ACARS ceases to run, but there may still be power to other systems. If made out, this would direct attention towards partial/total loss of power as a factor.

Question 2: what is the behaviour of the aircraft on loss of Bus 1 - eg by lightning. How long to recovery of any power, and what happens? This will affect hypotheses why there was a loss between 2:13:14 and 2:13:45 -- could it have been electrical, rather than attitude (or both)?

Observation 2: the permanent cessation of ACARS messages after 2:14 could also be due to attitude of the aircraft. But if BEA is correct, and the aircraft at least struck the ocean flat and vertical, then (assuming the plane was intact at that point) query whether attitude was an issue -- based on geometry, the antenna could have gotten a lock even at this point. This suggests there must be some other cause for why it didn't.

Observation 3: I don't recall people having canvassed the potential of power loss on FDR/CVR recording -- query if we may be disappointed even if they are found, as in SwissAir 111 or TWA 800.

Hypothesis 5 (speculation): Could we be dealing with weather induced disconnects and/or unreliable airspeed up to 2:13, followed by a power problem. Possibly unrelated - perhaps lightning after all? Engines out? First an interruption (2:13:14 to 2:13:45) then permanent loss up to some threshold that is not sufficient to power ACARS (after 2:14:28). Or could it be weather induced problems up to 2:13, then an attitude-induced loss of ACARS from 2:13:14 to 2:13:45, followed by a power-induced loss of ACARS (and again, query what level of loss).

Hypothesis 6 (pure speculation): Faced with this kind of sequence, assuming you had some control, what would you do? Head to Fernando de Noronhas (nearest airport) or Natal? Descent and U-turn? Might we even be reduced to a glide? It is here that Takata's excellent work ought to fit in.

[takata]

ttcse:
takata
Again, it is mostly your imagination: what clue do we have for considering the aircraft 'deceased' at 0214?On this point I'm with JD given: the preliminary report of essentially vertical impact on the belly, the projected positions at 0214 being in the neighborhood of the initial debris finds, and the most likely reason a satellite connection was lost. They tend to pair up. All other possibilities get more complex.1. What clue, on this impact description, is revealing to you the location of the crash? Why would she had to impact, "level with strong vertical acceleration" only exactly at the spot (or very close to it) where the contact by ACARS was lost?
2. The bodies drifted 100 NM (to the North) in five days after the first recovery but would have drifted previously 10 NM during the same time, and in the wrong direction (to the South-West), in an area where the drift is much stronger?
3. Why are they not able to detect the flight Recorders on this primary search location?
4. Why should we consider only the more extraordinary circumstances to fit this theory when we already have a sufficient one (icing) which may explain what happened?

I'm sorry, but the complexity of the postulat is not on the side of those I've made. I fully agree that my postulat is perhaps less obvious at the first look, but it is certainly fairly simple when you look at the whole situation much closer.

S~
Olivier

[WhyIsThereAir]

Tekata, unless I'm misreading something (quite possible) I think you misinterpreted the question in JD-EE's post. I think he was saying something like

assuming they were on course at 0210 and then decided they were in a bad place and for some reason decided to turn, what is the turning circle/radius at FL350 and 468kt?
Assuming they turned starting at 0410, and further assuming they hit sometime near 0414 or a little after, where could they have hit?Its my opinion that the impact point was some place they could physically reach in a descent from FL350 to FL0, with the descent and any associated direction change starting no sooner than 0210.

I'd like to know how sharply they could have turned in Alternate 2, starting at FL350 at 0210, and possibly descending thereafter.

In other words, can we match the airplane characteristics to the drift data and end up at the same point in the water?

[JD-EE]

singpilot
Remember, the 0214 time is the last received time for any datalink from AF447. Reversion to anything other than 'Normal AC Power' would have turned the ACARS system off. The plane could have been airbourne for some time after that, expanding the search area requirements.


Very good point. I still think it would help to define a minimum search area.

JD-EE

[takata]

Tekata, unless I'm misreading something (quite possible) I think you misinterpreted the question in JD-EE's post. I think he was saying something like
assuming they were on course at 0210 and then decided they were in a bad place and for some reason decided to turn, what is the turning circle/radius at FL350 and 468kt?
Assuming they turned starting at 0410, and further assuming they hit sometime near 0414 or a little after, where could they have hit?My bad if I misunderstood something, but have a look at the situation which could develop and tell me what you would do in the seat of F-GZCP's driver?

0209.. heading to TASIL, cruise, slightly deviating to the west in order to avoid a suspected dangerous cell.
0210.. AP/A/THR kicking OFF
.. ALT2, etc, warnings
.. thrust and AOA set to adequate values (N1=91, 3.5 deg?)
.. de-icing ON
.. troobleshooting start
0214.. engines rollback (ice)
.. pitch down to avoid stall
.. start emergency descent
.. cabin vertical speed advisory
.. engines flame out (after 15 mn of flight in CBs, mostly in Anvil)
.. EMER ELEC => ACARS fails, only HF1 & VHF1 left

What to do now?
1. aviate: avoiding stall?
2. navigate: where we go?
.. Cap Verde: ahead but too far
.. Brazil (Fernando Noronha) turn needed without colliding an active cell
3. communicate: Mayday? we'll see later, hands full now

What could be the turn radius in this case? Certainly the best possible in order to keep the aircraft under human control and not to lose too much speed/altitude? The turn-East option seems locked because of the bad cells, so turn to the West?

S~
Olivier

[JD-EE]

takata - used 420 as a bogey value. Fill in your real value.

singpilot came up with a good alternative. Another is that there were no more ACARS messages to send. The former is a very real possibility. The latter seems to my untutored intuition to be far fetched.

If the plane was within 20 degrees of horizontal it could communicate any ACARS messages that might be generated. Loss of power could do that. The fact that the plane hit near horizontal with, as I read it, a strong downward component to its velocity and some unknown speed along its heading.

I am not trying to identify why. I am simply trying to identify an approximate range of when. And absent an ability to continue on with battery power, somehow, there are not many things that would have it still in one piece much after 0214. Given a position report of 0210 and a presumption that the plane MAY have initiated a turn slightly before the report was generated where could it have gotten to? First guess is about 40 nautical miles from the position report's position. Within that radius lies the plane if the sessation of ACARS messages means it had no more problems it could report or did report before conact with the water.

If it came apart at FL350, that fits the criterion. If it went onto battery power, that fits the criterion and expands the search area. If it hit the water at 0214+, that fits the criterion. That it was under power and under controlled flight after 0214 does not fit the criterion.

How it got there is another question I am NOT trying to answer. I'm simply wondering "where are the most fruitful places to initiate search for the remains?" I would contend that the most probably circle for searching would be wthin 40 nautical miles of the 02:10:34 position report. Can that be refined? I'd presume yes, with a slightly smaller number, perhaps. I pushed the time range by allowing some delays on generating the reports.

Do remember, a long time ago I asked whether there might have been other ACARS messages cued after 0214. Nobody saw fit to answer that. Can you?
I am open to answers. I'm not open to screaming fits.

JD-EE

[PJ2]

Surplus1;
BTW, neither one of you answered my question with respect to the pilot’s ability to deliberately take the aircraft out of Alternate Law and force it into Direct Law if he so desires and I don’t know the answer myself. Although someone posted a fine diagram indicating which protections were retained in Alternate Law and which were lost, I do not recall them exactly. Safetypee you said you believe that stall protection is lost in ALTN Law but what I want to know is: Can the pilot go to Direct Law and remove all “protections” if he chooses to do so? From what I've read, stall protection is lost but stall warning is available from the AOA source.
The ability to take the Airbus into Alternate or Direct Law resides within the design of the autoflight system but is a profoundly non-standard approach with this design and is entirely within test-pilot territory.

I state this strongly because it is not even in the realm of an "ad-hoc, emergency response" to a badly degraded aircraft or flight control system. I could not see this kind of system intervention condoned or even considered by any Airbus pilot nor can I see it as a legitimate response in the present discussion.

This is because the flight control system, in Normal Law, does not prevent the crew from doing what is necessary to fly the aircraft within (and slightly outside of) expected maneuvers.

I think what you're asking is, is there a switch like there is in the 777 that connects the control column/wheel "directly" with the flight controls such that the pilot can exercise as much control input as is deemed required to intervene with abnormal regimes and attitudes. The answer, for both types, is, "no" in the sense that there is no more authority than is already granted by the flight control design when the aircraft is in such abnormal states, (system failures or abnormal attitudes). I have previously posted information on this twice.

The 777 switch bypasses the (equivalent of the) primary flight control computers but still sends electrical signals to the flight control servos in "direct control" (another name for direct law). In other words, control is achieved by wire, not cables/pulleys. (I assure you that I am familiar with and have flown the DC8, DC9 and B727 and have flown "manual reversion" in all these types in simulator exercises. The A320 can be flown on engine thrust and stab trim alone, to a successful landing). This is exactly the same as the Airbus 330/340 system except that the FCPC and FCSC - primary and secondary flight control computers execute the direct flight control orders from the stick. The available authority from the sidestick in alternate 2 law and direct law is, with minor variations in alternate 2 law, the same as would be available to a 777 crew in the same circumstances.

The essential decision by the design and engineering people is, because the autoflight system is beyond it's design capabilities either during a serious system failure (hydraulic, electrical or data-loss) or a "jet upset", (> 10deg ND, 30NU, 50deg roll, approximately), it can no longer reference and interpret the situation the aircraft is in and necessarily hands control over the flight crew.

This design is not a matter of "handing the aircraft over at the worst possible time" even though that is what it looks like - it is a matter of design practicality and software capabilities in rescuing a serious loss of control. In the Airbus, loss of hydraulics or electrics means that the autoflight system may not be capable of exercising all the control that is required of it when in Normal Law and so it is designed to degrade to Alternate Law in the 320, and Alternate 1 and 2 Laws, then Direct Laws in the 330/340. There is nothing about this that either intervenes in pilot direct control or prevents a pilot from flying the aircraft as s/he will. Any one of five flight control computers on the 330 will provide full use of all flight controls without restrictions. I have posted many schematics and diagrams illustrating both these laws, the degradation of same and the aircraft attitudes and/or system faults which will cause Normal Law (C* law as it is known) to revert to Alternate and Direct laws. The 777 degrades in approximately the same way.

I have to emphasize that there is nothing in the A330 design in terms of pilot interventions that were not available in the B707/DC8 design. The flight control computers do not mysteriously "modify" pilot input to do what the engineers and designers really want but haven't told the flight crew.

To be clear because there is a question, in Alternate law 1 & 2, pitch law is referenced to 'g' loading, (same as Normal law). The AOM does not specifiy that Pitch Alternate Law restricts 'g' loading to "2.5" but I suspect they do. In Direct Law, the aircraft is a "DC8".

The essential question is, "can the pilot get whatever 'g' s/he can pull above certification limits (2.5 positive, 2.0 negative, flaps up)? The answer is, yes in Direct Law and likely no, in pitch alternate laws 1 & 2, (1 is the same as 2 in pitch).

I hope this is of some help - I'm being a bit "direct" only to save space and not to dismiss concerns. This is the way the system works - there is only complexity, but not mystery. To explain the entire 330 autoflight system here would take substantially more space and would probably not be necessary.
I ask this question because the entire concept of the automated control system seems to be that it will prevent undesirable positions/attitudes, speeds, etc., as long as we are not in Direct Law. If we carry that concept to its limits - upsets, stalls and overspeeds simply can’t occur – so there is no need to waste time or money training for recovery from them. I do not believe that to be truth.Not entirely true, and for the reasons described above. Otherwise, we have a fully-automated airplane in which the pilot is just so muich "spam in a can", as John Glenn said to NASA engineers when they refused to give the astronaut some control over his Mercury capsule. In the end, it was Glenn who saved a mission via skill and manual control when the computers could not deal with a stuck thruster...

I therefore agree completely with your "If we carry that concept to its limits...etc". As much as it seems reasonable on the surface, we can't have it both ways.
Every effort and tons of money have been made and spent to keep the Space Shuttle safe yet the vehicle has been lost twice. We build things that we say are ‘fail safe” but nothing is truly fail proof.The latter part of the statement is absolutely true. Some have mentioned Murphy's Law and variations on the theme.

Even without a creeping hubris focussed on "the mission" rather than the traps, a characteristic which can infect and even convince the most skeptical to ignore the "nay-sayers", and under the very best of managerial and engineering intentions and comprehension of the risks at hand, we can still fail extremely badly.

It is not that failures occur of course; It is what we have done with the inevitable but frequently ignored precursors to a major accident that we must surely reflect upon. For me, that is the case here, but truly that is an old aviation story indeed. What happened to AF447 after 0215Z is immaterial in terms of systems design, aircraft response and crew handling.

I note that the shuttle accidents are referenced in comparison to automation accidents regarding "tons of money" etc. I disagree with this comparison and the reasons stated, and although it is perhaps a side-bar, I would suggest, if I may, a close reading of Diane Vaughan's book, "The Challenger Launch Decision", and Moshe Farjoun's and William Starbuck's edited book, "Organization at the Limit" for a full understanding of why the Challenger and Columbia disasters occured. In almost every aspect, they bear very little relationship to this accident.

[JD-EE]

takata, sorry if I'm grinning ruefully here, sir. I don't know. Essentially I am asking regardless of the pilot's decision how far away from his position report at 02:10:34 could he have gotten in the time between 0210 and 0215.

It has been pointed out he could be further away on what, if I understand the power situation correctly, would have been an unpowered glide. That might extend the search for the second level of probability.

When we can draw those circles we learn something. If we can map drift backwards into one of those circles that means something important. If we can't, well, I notice the positions and the drift rates diagram simply do not seem to fit at all well. That suggests a problem with the data or our interpretation of it. Scrap the hypothesis and work on another. Your work is good thinking. It just arrived at a bad conclusion, likely because of presumptions about the currents that were not true. It's not your fault or anything. It's our groping for understanding with inadequate data.

JD-EE
edit - change an It's to be more specific.

[HazelNuts39]

tanaka (post#3170)

quote: "What could be the turn radius in this case? "

Turning at 468 kt TAS at various angles of bank:

Bank angle (deg) 15 30 40
Loadfactor 1.035 1.155 1.305
Turnradius (NM) 11.9 5.5 3.8
Turnrate (deg/s) 0.625 1.348 1.96

Does this help?
HN39

[SaturnV]

One comment, one note, two images.

I assume the turbulence penetration speed for an A-330 is not mach 0.82.

I re-found the lat & long for the VS recovery point on June 7 (unofficial source): 3.41N, 30.42W. The first body(ies) recovered were June 6 at 3.34'05"N 30.27'18"W. There is a progressive northward recovery of bodies and wreckage over time, although recoveries in the latter days of the search are significantly more north and west of Tasil. (I assume the searching vessels were on courses from south to north as they recovered. If they had been on a north to south course, they would have intercepted the drifting wreckage sooner.)

This is the French bathymetric profile. No coordinates are given, but if the grid is the same as the chart prepared for the bottom sediment, it is roughly centered on 3.0N and from 30.0 to 30.65W

http://i136.photobucket.com/albums/q199/tahitiplage/SNAG-0324.jpg

http://i136.photobucket.com/albums/q199/tahitiplage/SNAG-0325.jpg

Unfortunately, the western sectors of the search area are the more mountainous and rugged, and likely to impede locating and/or retrieving the FDR and CDR.

[OleOle]

What to do now?
1. aviate: avoiding stall?
2. navigate: where we go?
.. Cap Verde: ahead but too far
.. Brazil (Fernando Noronha) turn needed without colliding an active cell
3. communicate: Mayday? we'll see later, hands full now

I see the logic in your conclusion, but how long would it take to glide down from FL350 over a distance of ~100 nm ? (15-20 min?). I think the closer they would get to the surface the higher their priority to communicate would become. Taking into acount that in this scenario they would have had sufficent time (and a crew of three) one would expect distress calls to be made on 121.5 and to be picked up by nearby a/c.

[dougydog]

Just had this email sent through...

Dear All, Bonjour.

I would highly appreciate if you could answer me asap regarding our question below; we would need the answer this afternoon by latest.

many thanks for your precious and much appreciated cooperation.

merci,

Carole

Request from SNPL Air France ALPA - M. Louis JOBARD, President of SNPL Air France ALPA.

URGENT

Could you please tell us which airlines in your country, whom your union represents the pilots,

have already retrofitted (or decided to do so) their A320/A330/A340 with the system :

BACK UP SPEED AND ALTITUDE DISPLAY suggested by Airbus since 2007.

Many thanks for your diligent and precious cooperation,

With my best regards,

Ms Carole ARNAUD-BATTANDIER
International & Technical Coordinator SNPL - France ALPA
Email: [email protected]
Direct land line: +33.(0)1.49.89.24.03 / Office: +33.(0)1.49.89.24.00
Mobile: +33.(0)686.709.702

[NARVAL]

PJ2, it would be difficult to do better than your exhaustive answer. But to help (maybe) answering the question "switching deliberately from alternate to direct law" and as a former airbus driver I knew that at least, what would come to mind when you are not a test pilot, when there is no test flight engineer sitting back in the cabin with all test equipment would be ...lower the landing gear. You are in direct law and you put your hand on the trim wheel and you understand, now, what your trim balance is ...sorry if this seems very simple-minded and even stupid, but when you are lost with out-of-trim airplane and inefficient stick inputs, at least you go back to basics. It would have to be a very frightening situation to go to such extremes (apart from landing gear speed and altitude limitations which you maybe would not care about anymore) but it might save the day, only, of course, considering that the alternate law might be going mad at the absent airspeed(s) informations.

[AstraMike]

Thank you, Surplus1; for your post # 3061 and post #3144.
And thank you, Woodvale; for your post 3155 too.

It seems to me we are pretty close to saying much the same thing, certainly there are many big ifs involved at this stage and maybe always will be. My point was and is to take what seems to be judged as “known” or believed by competent authority and see if it fits anything known in the world of aerodynamics. If there is a fit, and it seems to me that there might be, surely it is interesting and should lead one to wonder about less sure assumptions.

Here, for all you spin skeptics, is a little food for thought and although I may, in the large part, be preaching to the converted, it seems it still needs to be said.

A modern swept wing airliner has somewhat different stall characteristics from straight-wing aircraft that many of us may have stalled when training in the past. The difference is that although straight wings tend and are encouraged to stall at the root first, aft-swept wings tend to want to stall at the wing-tips first, rather than at the root. With a swept wing, the Center-of-Lift may move ahead of the Center-of-Gravity (CG) at the stall causing a pitch-up moment. And so the aircraft may begin descending in a nose up attitude unless positive forward pressure on the controls is applied (Straight-wing aircraft will usually pitch down on their own accord when the stall occurs, as long as they are within aft CG limits.). That is why swept-wing aircraft have stick shakers that give an artificial warning of impending wing stall. Many also have stick pushers to force the aircraft to a lower angle-of-attack before the stall progresses too far. Many types of aircraft will tend to roll or yaw if recovery from the stall is delayed, and swept wing aircraft are particularly prone to becoming laterally unstable as the stall progresses. A spin can be thus inadvertently entered. An aircraft might be very stable in “normal” conditions, but once you find yourself at stall speeds; the rules change.

To further complicate the problem, those aircraft with engines mounted underneath the wings can experience a further pitch up, since the engines' thrust lines are below the aircraft's CG. The pitch-up associated with adding power can cause the stall to worsen, if the controls are not moved forward to counter this tendency, or if emphasis is not placed on lowering angle-of-attack first with forward pressure on the controls.

Swept-wing aircraft do not normally have the luxury of engine or propeller wash over the horizontal tail and elevator, to aid in pitch control. Therefore, if a pilot encounters an impending stall in such an aircraft, he has been taught to hold the pitch attitude and apply maximum power to minimize altitude loss and to "fly" out of the stall. The success of this recovery lies in the fact that a stall has not yet occurred (the stick shaker will typically activate at an airspeed 5-10% above the stall speed.). Thus it is not really a stall recovery at all, since a stall has not occurred.

It also seems that there are a variety of ideas regarding just what a flat spin is, clearly, a number of them are quite wrong. Let me just say that regardless of how it was entered, in a flat spin one wing will have a large angle of attack and the other a smaller angle of attack, in comparison to the relative wind, which is CB activity could be coming from almost anywhere. Both wings might be stalled, but not necessarily so and one will be stalled more than the other. Thus, you can have a doubly stalled flat spin and also a singly stalled flat spin.

In a non-spinning airplane, if one wing were producing more lift than the other, that wing would rise. So the question is; why is a flat spin stable? Or, why doesn’t the outside wing continue to roll to ever-higher bank angles? The answer is centrifugal force. In an airplane spinning about a vertical axis, the high (outside) wing will be centrifuged outward and downward (toward the horizontal), while the low (inside) wing will be centrifuged outward and upward (again toward the horizontal). In a steady flat spin, these centrifugal forces cancel the rolling moment that results from one wing producing a lot more lift than the other.

As has been mentioned previously in this thread, in the 1970s, NASA conducted a series of experiments on spin behavior. They noted that there was “considerable confusion” surrounding the definition of steep versus flat spin modes, and offered the classification scheme shown here.



SPIN MODE:............STEEP;.....Mod’ly Steep;..Mod’ly Flat;...FLAT;
ANGLE OF ATTACK...20 to 30... 30 to 45....... 45 to 65........65 to 90
NOSE ATTITUDE......extreme nose-down....... less nose-down
RATE OF DESCENT...very rapid.....................less rapid
RATE OF ROLLK.......extreme....................... moderate
RATE OF YAW.........moderate..................... extreme
wingtip-to-wingtip
DIFFERENCE in ANGLE
of ATTACK.............modest........................ large
nose-to-tail DIFFERENCE
in SLIP..................large........................... large


The angle of attack that appears in this table is measured in the aircraft’s plane of symmetry; the actual angle of attack at other positions along the span will depend on position. Notice also that in a flat spin the rate of yaw is extreme and angles of attack are quite large. indeed.

In all cases NASA studied, the flat spin had a faster rate of rotation (and a slower rate of descent) than the steep spin. Meanwhile, there are reports of experiments in which the flatter pitch attitudes were associated with slower rates of rotation. This is not a contradiction, because the latter dealt with an unsteady spin (with frequent changes in pitch attitude), rather than a fully stabilized flat spin. A sudden change to a flatter pitch attitude will cause a temporary reduction in spin rate, for the following reason.

In any system where angular momentum is not changing, the system will spin faster when the mass is more concentrated near the axis of rotation (i.e. lesser moment of inertia). By the same token, if the mass of a spinning object is redistributed farther from the axis, the rotation will slow down.

When the spinning airplane pitches up into a flatter attitude, whatever mass is in the nose and tail will move farther from the axis of rotation. Angular momentum doesn’t change in the short run, so the rotation will slow down in the short run.

In the longer run — in a steady flat spin — the aerodynamics of the spin will pump more angular momentum into the system, and the rotation rate will increase quite a lot. The rotation rate of the established flat spin is typically twice that of the steep spin.

Recovering from an established flat spin requires forcing the nose down. This brings the mass in the nose and tail closer to the axis of rotation. Once again using the principle of conservation of angular momentum, you can see that the rotation rate will increase (at least in the short run) as you do so.

As for the point of rotation, it is likely found some way from the inner wingtip following the axis of rotation from outer wingtip via c of g to inner wingtip to point of rotation – the aircraft does not “spin like a top” as some seem to think.

Lastly, in turbulence with a high angle of attack and a stalled wing, you do not need a rudder to induce a spin; adverse yaw brought on by aileron drag in an attempt to level the wings will do just fine. Which is likely why, when learning, we were always taught to use rudder only; at high angles of attack leading up to Insipient Spins. Power will hold the aircraft in the spin; as long as the engines produce thrust and I suspect there would be little if anything the crew could do to recover, regardless of skill, especially on instruments.
Do you think you could recognize a spin in IMC?

The mentioned Russian aircraft that crashed following a “flat spin” entered at altitude, in turbulence, had a Second Officer who was a qualified aerobatics pilot - not that it helped.

So far, although there are those who scoff, no one has yet suggested a solution to better fit what little is known of the end result; damage observed from recovered debris or any of the other evidence, scant though it may be, and I suspect if taken a little more seriously it would be found that other things fit a spin solution too.

Yes, there are many unknowns and much we don’t know but IF AF447 DID fly into moderate to severe turbulence and IF that did cause and inadvertent loss of control and IF that is what the ACARS messages started to try to tell home base and IF yaw and high angle of attack caused loss of power and loss of satellite communication. Would the aircraft likely end up as it did? The idea is to suggest a solution that allows the evidence to fit, not manipulate the evidence to fit a solution.

[ttcse]

takata

As for the likely sequence from 02:10 to the surface, several times others have posts which is essentially the camp I'm in. (control difficulty starting around 02:10, upset at some time, essentially stall/spin, flight ending at 02:14 or soon after, not much distance to be traveled after 02:10, fin-off at impact.) Not that it makes me credible but I don't want to repeat their work, I'll let their posts do the talking.

but this part2. The bodies drifted 100 NM (to the North) in five days after the first recovery but would have drifted previously 10 NM during the same time, and in the wrong direction (to the South-West), in an area where the drift is much stronger?With all the official, credible and yet conflicting sources of current and drift information, I'm not so certain myself what the drift at impact site was at the time of crash. One of these official sources, posted here a couple times by SaturnV using this OSCAR - Ocean Surface Currents Analyses - Realtime (http://www.oscar.noaa.gov/datadisplay/), causes trouble for your drift back-track projections. While it agrees with all the northish drifts at the middle and northern side of the 0210-0214 area, on the south side of this it shows an eastward flow. The specific place it begins, direction and speed on the date/time of the crash could very well been to the east for all we know. I can only argue for 'uncertainty' and some question of the back-track projections. I know you're aware of wind & weather conditions at the specific time of the crash that could potentially throw a wrench into the projections.

[LeandroSecundo]

Hi,

Do remember, a long time ago I asked whether there might have been other ACARS messages cued after 0214. Nobody saw fit to answer that. Can you?
I am open to answers. I'm not open to screaming fits.

JD-EEAs I commented when it was first time posted .. it's a very interesting point ... and from all the noise here I wait also some answer to this question :)
If I speculate ... the plane after 0214 was completely out of control (no more contact between antenna and satellite due to aircraft movements) or .. the plane was no more in one piece ......

Bye.

[surplus1]

Dougyboy, re your #3177

Most likely too late by now or already done but just in case: Your friend Carole might be able to use an additional source of information. I believe NWA (US) is the world's largest operator of the A-330.

She should contact ALPA-US

ATTN: Capt. Rory Kay
Executive Air Safety Chairman
email: [email protected]
US Tel: 703-689-4200

I'm certain Capt. Kay would be happy to assist in obataing that information or any other that might be helpful from US operators of ABI aircraft.

Surplus1

[AstraMike]

I thought it was well established that it took a while, days in fact, depending on surrounding temperature, before a human body would float. Equally, the conditions below the surface are different than those on the surface.

Therefore you cannot base constant drift assumptions on the bodies, until they surface.

Strangely, it seems to me that the remains are largely co-located with other debris, along a drift trail, although I stand to be corrected. If I am right - this has to be wrong, unless the debris started to surface and float at about the same time that the bodies did, give ot take a bit for wind effect.

Either way, you surely can't extend the drift line back assuming a constant drift rate? And then, what was the sea state at the time of the accident and what account has been taken of this?

There has to be an answer that precludes a 180 turn in inclaement weather where a stall or overspeed are real threats as I doubt very much that this would have been achievable and once in the throws of disaster the winds at the time, let alone wind shear, would have taken control of the direction of the aircraft, likely moving it off track.

Ciao

[BJ-ENG]

There is one view that at the time a body enters the water it either sinks or floats subject to such factors as the amount of fat content, and clothing which will trap air. Cold water tends to inhibit resurfacing, and if sufficient deep is reached no amount of decomposition gas will overcome external water pressure (Schafer 1978)

Advances in forensic taphonomy By Haglund, and. Sorg

- BJ

[SaturnV]

It does not always take a while for a body to come to the surface and float. When the Aegis shot down Iran Air in the Persian Gulf, some of the bodies floated on the surface immediately.

As for current drift, here is the plot of the last body recovered and wreckage recovered on that day (June 17).

http://i136.photobucket.com/albums/q199/tahitiplage/SNAG-0327.jpg

Here is the surface current for a five day period centered on June 17, 2009, using NOAA/NASA satellite observations (OSCAR) to generate the chart.

http://i136.photobucket.com/albums/q199/tahitiplage/SNAG-0328.jpg

To me, there looks to be a pretty fair correlation between the surface currents and the plot for recovery of the objects and body. I'll leave the calculation of Reynolds numbers for a human body half-floating on the surface to others.

The 45 day meteorology for the closest buoy (0N, 35W) can be found here:
http://www.ndbc.noaa.gov/data/realtime2/31001.drift

[Philemon]

As Air France has very bad safety statistics (4 aircrafts destroyed and 341 deaths in the past 10 years), I would like to study the report of the 1989's Dryden crash which seems to present some similarities on structural causes.

Does somebody have this report or a large summary of it ?

Thanks much...

[einhverfr]

AstraMike:


The mentioned Russian aircraft that crashed following a “flat spin” entered at altitude, in turbulence, had a Second Officer who was a qualified aerobatics pilot - not that it helped.


I thought I read that the 2nd Officer was a former national champion at aerobatics, which strengthens your point about how hard it is to recover. I cannot personally imagine any passenger liner recovering from a fully developed flat spin (maybe a fighter with thrust vectoring might be able to do it, I don't know).

[Rob21]

Here in Brazil, small a/c engaged in air-taxi/corporate operations MUST have at least one ELT, and operated by a G-Switch.

You can have as many manually operated ELTs you want, but at least one should have the G-Switch.

If this is true on much smaller a/c (including helicopters), I want to believe A300s also has one.

Supposing this is true, why not a beep was heard? ELTs transmit on 121.5, the freq. everybody is "listening" to, specially when crossing the "big lagoon"...

[DozyWannabe]

Philemon:
I don't fully understand where you're coming from. Any airline can have a run of bad luck. Pan Am's safety record form the '60s to the '80s could be considered very dodgy by your standards - hell, they lost 341 in a single incident!

Lest we forget, in the case of one of the AF hull-losses everyone got off safely. Trying to compare the Dryden crash, presumably to point a finger at AF for allowing commercial pressures to override safety when in fact the incidents are nothing alike, just smacks of a desire to smear.

[ttcse]

Rob21Supposing this is true, why not a beep was heard? ELTs transmit on 121.5, the freq. everybody is "listening" to, specially when crossing the "big lagoon"...

Or were the ELTs the new 406 MHz models???

Verbal maydays would be on 121.5 or 243.0, guys listen there. The one ELT found wasn't armed and the others drowned after some time.

[PEI_3721]

AstraMike, your ‘aerodynamics lesson’ {post 3197} showed how a modern large aircraft might enter a spin, but not with any relationship to the A330, nor why you focus on a flat spin in preference over a more common type. Similarly, where stall precedes a spin, you provide little supporting evidence, unless you agree with some of the previous ideas – then why ‘pick and choose’ evidence to suit your case.
Also the choice of spin mode appears back driven from the scant evidence of the wreckage, for which the conditions in many other scenarios might account for the damage.

If an aircraft has a tendency to drop a wing during a stall then the resultant downward attitude/motion could just as likely provide the necessary increase in airspeed to un-stall the wings – thence a spiral dive and not a spin.
All that the current evidence points too is the loss of airspeed information, procedural flight on standby horizon and power setting, and in atmospheric, procedural, and WAT conditions conducive to low speed loss of control (stall).

Noting some interesting observations on trim operation, how the loss of airspeed procedure might be adhered to in the absence of stall identification, and generalities about crew training performance, there are still many unknowns.
Should we expect the airspeed display to be regained as the aircraft descended clear of icing conditions?
If there was a loss of control and instruments were recovered, why wasn’t stable control wasn’t regained?
Please no wild speculations about locked in spins – first show that this aircraft type could, or would experience a stall, an incipient spin, then a ‘spin’, and then why ‘flat’’.

[Rob21]

ttcse,

This is strange, ELTs for extended overwater operations can be manually operated, but should actuate upon contact with water.

Unless this ELT found was completely dry, then I can understand why it didn't actuate. Switched to off position, ELTs will transmit when wet. This is a requirement, I believe.

I can be wrong, though...

[surplus1]

AstraMike - Re your # 3179 - "Flat Spin"

Thank you; excellent post.

It seems to me we are pretty close to saying much the same thing, certainly there are many big ifs involved at this stage and maybe always will be. My point was and is to take what seems to be judged as “known” or believed by competent authority and see if it fits anything known in the world of aerodynamics. If there is a fit, and it seems to me that there might be, surely it is interesting and should lead one to wonder about less sure assumptions. [Emphasis by S1]

The idea is to suggest a solution that allows the evidence to fit, not manipulate the evidence to fit a solution.

That was precisely my intent. Obviously I do not know if a "flat spin" occured. I suggested the hypothesis only because the BEA opined that the aircraft struck the ocean in a level flight attitude with a near vertical trajectory. If that did happen a "flat spin" seemed (to me) to be the only thing that could make it so. It goes without saying that a flat spin or any other type of spin - did not cause the upset but is only a possible aftermath that might fit the evidence of a touch down on the belly.

Your description of a flat spin is quite on the mark. The one place we might differ is on what would keep the aircraft in a sustained flat spin. I do not think that possible unless there is a failure of some kind in the tail section or the separation of engines from their mounts, or both. Otherwise, I believe, the "flat spin" would change to a normal spin or a spiral.

The stated impact evidence in the BEA report appears to preclude a normal spin or a spiral.

[ArthurBorges]

My personal understanding is that, at impact, the fuselage was parallel to the ocean surface.

[ttcse]

Rob21ELTs will transmit when wet. But when submerged, the radio signal would be significantly attenuated. At some minor depth unhearable by other airliners. ( And again xmitting on 121.5 or 406?? )

Off & still triggered by being wet? I could be wrong but I believe it needs to be set to the 'armed' setting. Off is off.


AstraMike, many long posts so I'm starting to skip but your #3179 was a good read.

[Hyperveloce]

"Observations of the tail fin and on the parts from the passenger (galley, toilet door, crew rest module) showed that the airplane had likely struck the surface of the water in a straight line, with a high rate vertical acceleration".


"Les observations effectuées sur la dérive et sur les éléments de la cabine
passagers (office, porte de toilettes, module de repos PNC) font apparaître que l’avion a vraisemblablement heurté la surface de l’eau en ligne de vol, une forte accélération verticale"

To me, it means that the plane's trajectory was rectilinear both in the horizontal (en ligne de vol) and vertical planes, with a velocity vector close to the vertical. It would also imply that the plane was not banking or not spinning at the impact.:oh:
Jeff

[einhverfr]

Hyperveloce:

I agree about the unlikelihood of a flat spin because if it was a spin, we would expect a strong sideways force on the VS, while BEA stated that it failed forward and only slightly to the left. This implies horizontal deceleration as well, along the line of flight.

[FrequentSLF]

To me, it means that the plane's trajectory was rectilinear both in the horizontal (en ligne de vol) and vertical planes, with a velocity vector close to the vertical. It would also imply that the plane was not spinning at the impact.

To determine if the aircraft was spinning, IMHO, you should look in which attitude was before impact, the BEA statement does not clarify that.
A spinning object when impacting ground is horizontal and has a velocity vector close to the vertical. Unless you know the horizontal vector before impact you cannot establish if was spinning or not.

[netstruggler]

une forte accélération verticale"

It seems rather sloppy text even in french. Surely it should say velocity or speed, since I don't see how it can be deduced whether or not the aircraft was accelerating at the time of impact.

[rgbrock1]

Why is it out of the realm of possibility that there could have been an uncontrolled fire on board AF447? I see no one entertaining this possibility.
Along the lines of SwissAir 111. An uncontrolled fire on board would certainly bring any aircraft down. Or am I way off base here?

[takata]

AstraMike:
I thought it was well established that it took a while, days in fact, depending on surrounding temperature, before a human body would float. Equally, the conditions below the surface are different than those on the surface.
Therefore you cannot base constant drift assumptions on the bodies, until they surfaceHi,
This is what most people think but, having being involved in several sea rescue operations in the past, I can tell you that it isn't true (or partially wrong) from direct experience. Sorry for the following details.

Like any objects in water, there is three cases: sink, float or stall.

It is based on the differential between object and sea water specific gravity. In clear water, the tendency for the large majority of humans (+90%) is to sink, because their specific gravity is higher than clear water (0.97) but in standard sea water (1.027), it is the contrary and the majority of human (+70%) is naturaly buoyant. Some will have an equal gravity and stall close to the surface but 100% submerged for some time. The buoyancy of most human is very close to 0, say 0.01 meaning that only 1% of the body will surface and it will be almost invisible at some distance.

Now, when one sink, he will go to the bottom and, if deep enough, he will never re-surface because of high pressure compressing the human body added to higher density of deep and cold water. In tropical seas, the high temperature of water means lower density and a higher sink rate.

Plenty of factors will affect people buoyancy (like age, gender, physical condition, etc.) but the most important one, considering disasters at sea, will be the clothing which may affect buoyancy one way or the other. Victims will usually float face down, with a very small part of their back immerged during several days, then they will start to turn belly up after some time, depending of the sea temperature.

In conclusion, it is nearly impossible to predict how many people will surface immediately following a disaster and it is very common to miss some of them until they reach some very remote coastal areas, sometime after drifting for months over several thousand of milles.

S~
Olivier

[Clear_Prop]

What to do now?
1. aviate: avoiding stall?
2. navigate: where we go?
.. Cap Verde: ahead but too far
.. Brazil (Fernando Noronha) turn needed without colliding an active cell
3. communicate: Mayday? we'll see later, hands full now

and...


I see the logic in your conclusion, but how long would it take to glide down from FL350 over a distance of ~100 nm ? (15-20 min?). I think the closer they would get to the surface the higher their priority to communicate would become. Taking into acount that in this scenario they would have had sufficent time (and a crew of three) one would expect distress calls to be made on 121.5 and to be picked up by nearby a/c.

Before completely ruling out the possibility that the aircraft may have glided or attempted a controlled descent/diversion and ultimately compromised ditching, is it worth considering again that the report mentions the swapped RMP1 at Rio?

I dont mean to introduce any extra area of unecessary speculation, but can we rule out takata's scenario purely on the basis of assumed certainty that comms were fully operational on the A/C? - whether post upset or for that matter during the whole flight?

Is it possible that all the radio calls leading up to the incident were made using RMP2 up until the initial point of the scenario developing; and that thereafter the person operating RMP1 subsequently took charge of putting some emergency calls in, possibly on several occasions? With a rapidly developing situation and the knowledge that they were in the midlde-of-VHF-nowhere... can we rule out the possibiility that even in a controlled emergency descent, the crew may have overlooked a function check / repeat calls on RMP2, feeling that calls had been made as per procedure?

[PJ2]

NARVAL;

Lowering the gear would certainly place the aircraft in Direct Law but to what end? The thesis is, the pilot has "more control" to push/pull the aircraft out of an abnormal attitude - the "kind of control" we find on more "accessible" designs such as those that don't have control laws to "interfere" with what the pilot would do with the controls. I submit that such thinking is faulty and not supportable in fact.

I understand the long-posited argument that when circumstances are so dire that access to all possible control (direct law) with the attendant possibly of a) high-speed-stalling of the aircraft or b) breaking the aircraft, is preferable to the certainty of a crash. But this argument presumes that there is more performance available from the aircraft, under the 'g'-loads and/or attitudes/speeds contemplated, than the control laws are permitting access to. In the absence of clear cases to the contrary, the question then becomes, is there a very slight hint of romanticism in assuming that "the airplane ain't read the manual" and that the pilots would, in all cases, be better off with immediate and full authority over all flight controls, setting aside the engineering data regarding structural and aerodynamics issues?

The argument then takes both forks in the automation road: Design software and hardware that will prevent such excursions in all cases, thereby removing the pilot altogether, or hand full authority over the aircraft in all cases, thereby placing recovery of the aircraft in the pilots' hands. Control laws in fbw aircraft occupy the design-space in between these two forks in the road.

I can't think of a single accident where this kind of reversion (instant access to Direct law via the "big red button" notion) would have made a difference in the survival of the aircraft, bearing in mind that such laws may already be exercising that very fine balance between loss of control (high-speed stall through pulling 'g') and breaking the airframe and that the aircraft has no more to give, (Perpignan case?) On the contrary, we have at least one clear example where Airbus and 777-type laws would have saved the aircraft, (AMS B737).

At the same time I recognize the complexities of the issue and would not hold out such a view if it could be demonstrated otherwise but if that were the case, (and perhaps this lies in "greatest hope" territory), likely Airbus and probably Boeing would be far ahead of any of us in responding with a different view of computerized flight and its reversion laws.

[RatherBeFlying]

une forte accélération verticale

It seems rather sloppy text even in french. Surely it should say velocity or speed, since I don't see how it can be deduced whether or not the aircraft was accelerating at the time of impact.Acceleration in this context is physics / engineering speak for the forces on impact.

In layman's terms: It hit the water going pretty much straight down in normal flight attitude.

That does not preclude horizontal or rotational components on impact, but the deformation pattern led BEA to say: Les observations effectuées sur la dérive et sur les éléments de la cabine passagers (office, porte de toilettes, module de repos PNC) font apparaître que l’avion a vraisemblablement heurté la surface de l’eau en ligne de vol, une forte accélération verticaleIf significant distortions in other planes were apparent, I expect BEA would have noted that in the preliminary.

[Will Fraser]

Jeff, EMIT,

Without intending to do so, I may have hyperfocused my disagreement with BEA terminology. In and of itself, the phrase en ligne de vol is reasonably benign. To take issue with it involves a very strict 'raison d'etre'. It may be a non charged description of horizontal for whomever wrote the piece. The writer isn't responsible, the group who approved the text is. As Surplus1 so eloquently points out, this report is composed by parties who have well defined and difficult to disguise interests in the ultimate understanding of the piece by all who read it. As such, it is a rehash of all the information already known, exclusion of information that would lay responsibility on an interested party, and is essentially useless.

Without substantiating a conclusion of hull integrity, they claim it by 'visual inspection'. No supporting engineering, no metallurgy, no independent or reviewed analysis. They rely solely on their authority to conclude to do so. This report is opportunistically political.

To those who would rely on ACARS as if it was some stand in device for FDR, the reality is far from relational. It is the poor passengers who have the most important evidence for a sincere path to the truth and consequent aeronautical progress.


Some here have already concluded ice was the procuring cause of upset.
Possible. So is a pneumatic anomaly vis a vis statics due to turbulence, or even within-the-envelope control excursions. Not to mention an upset already in progress.

The temptation for any lay theory is to base it perhaps solely on what you know best. Currents, Wx, AB systems, AF, etc. etc. I have no specific field other than 40 years of flying. Weather is my worst fear, followed by IMC vs. visual, followed a long way behind by airframe and powerplant issues.

It is worth noting that this thread is backwards. Starting with fussy even arcane and overly technical "evaluation" of what amounts to almost no evidence, I'm stuck where I was on day 1. A modern, well built, and state of the art wide body disappeared suddenly when all indications were that she was just fine. The best place to start is with what is known. A history of unreliable a/s followed by less than dependable computer track, followed by a thus far successful (albeit problematic) incident recovery. With the weather in the area of travel, and some mx tx, one would assume at the outset an upset or similar incident followed by this time an unsuccessful recovery.

"Wait for the Report".......... Why ?

Will

[HazelNuts39]

Like you, I was puzzled by the fact that, in contrast with the rest of the report, that last bullet of the Findings is so poorly worded. Was it hastily re-edited at the last minute? I guess it was probably meant to say something like:

- based on that fact, and on visual examination of various elements, it would appear that the airplane was not destroyed in flight, that it was essentially aligned with its flight path at impact, and that impact forces resulted in high values of acceleration along the airplane’s vertical axis.


I researched Wikipedia for "en ligne de vol" and got 4 rsults, including the BEA Interim Report. The best I can make of those results is "flight attitude" or "aligned with flight path"



HN39

[vovachan]

Why is it out of the realm of possibility that there could have been an uncontrolled fire on board AF447? I see no one entertaining this possibility.

Because no evidence of fire was found?

[pineridge]

Is it at all possible that the aircraft in question could have had a catastrophic encounter with hail at altitude- possibly taking out the pitots, angle of attack indicators and maybe even compromising the windshields and causing a rapid decompression, thus incapacitating the cockpit crew?

[takata]

@ PJ2, Hi,

Is it possible to ask you if you could compute how far could have glided F-GZCP following a double engine failure due to icing @ FL350 or close (~260 kts /210t), as you already suggested a long time ago (I took this very good point from you :)), including a near 180 deg turn with max energy conservation? (I guess, at this point, the turn radius would have been much less important than the amount of altitude/speed wasted).

- Would it be possible for her to dump fuel if necessary after EMER ELEC? (keeping enough to restart engines and reach F. Noronha or Brazilian coast?)
- What would have been the odds for the RAT to supply power and to restart engines, considering the heavy rain possible at lower alt?
- What would be the risk of loss of control when restarting engines?
- In the paper about engine icing, they mentioned that engines would not restart above 10,000 ft, have you got an explanation for that?

Thanks in advance (and nothing urgent to answer, just some thought)
S~
Olivier

[24victor]

Why do people make a habit of starting with "I'm not trying to be contentious" or "I don't know anything but..." and then go on to lay out meaningless theories and hypotheses which they then reverse in later posts? If you don't know, don't guess - just try asking instead.

24V

[ClippedCub]

Is it at all possible that the aircraft in question could have had a catastrophic encounter with hail at altitude

The VS L.E. paint condition rules out a mayor hail event.

[md80fanatic]

we are no closer to an answer than we were in early June. :(

Evidence retrieved is inconclusive, searches have been terminated for the most part, and the pingers are likely dead or too weak to be heard. Barring a miracle, no further physical evidence will be found (and this crash will remain a mystery).

[Hyperveloce]

the aircraft entered into a mesoscale Cb, it may have encountered moderate turbulences (AMDAR), ~02:10Z at the time when it may have experienced very low temperatures (from known last pos./traj. and satellite IR imagery), sudden cascade of fault reports, corrupted airspeeds, loss of flight assistances/ALTN 2, possible multiple stall alerts resulting from largely underestimated airspeeds due to Pitot freezing (from past cases like Air Caraïbe, not an established fact), QRH/procedures implementation, crew intructed to react to stall alerts (because based on the AoA not airspeed), pich & thrust and manual flight, possible reset attempt of PRIM/SEC (crew still struggling with their avionics around 02:13Z ? not an established fact, one of the 2 possibilities).
believing in an imminent stall as requested by the procedure (taking the opposite choise than the one made by the Air Caraibe Cpt), what would be the appropriate action then ?
pich down or/and augment thrust, trade altitude for speed ? Would the most probable outcome of such an action be an overspeed ?
If yes, between a high altitude overspeed and an aircraft falling nearly like a stone on the surface with a slightly positive pich (damages on the VS) or on its belly (as described by the BEA, but still "in line of flight", suggesting with the suitable attitude to fly), what could be the missing link/event ?
-could a high speed mach buffet resulting from the overspeed (wrong reaction to a stall alert) explain a stall initiation ? (with a rear CG at >35 % of RC). Are there such things like a stall with a positive pich ? (nose up/tail down). Could the reversed air stream have flamed out the engine or tore the spoilers/ailerons away from the wings ? could it result in a near vertical fall with very little residual lift ?
-or could an attempt to stabilize the altitude (ressource) in overspeed have generated excessive load factors (positive Gs) or aerodynamical stresses, in particular on the control surfaces like the ailerons ? could the loss of control/stall have originated from their failure ?
-or could a severe ice ingestion have flamed out the engines, making the AF 447 at best a glider without airspeeds and visibility in a tropical Cb. wouldn't this suppose a significant horizontal speed at the impact with the surface (compatible with BEA findings on debris, on the Galley G2 ?)
-or could a severe updraft or windsheer have driven the plane out of its flight enveloppe like the Russian plane ? (worsenned by the FMGEC/windsheer prot. impaired ?) doesn't this option render the Pitot freezing event as incidental ?
Jeff

[ClippedCub]

Your description of a flat spin is quite on the mark. The one place we might differ is on what would keep the aircraft in a sustained flat spin. I do not think that possible unless there is a failure of some kind in the tail section or the separation of engines from their mounts, or both. Otherwise, I believe, the "flat spin" would change to a normal spin or a spiral.

For clarification, Astramike's description of a flat spin is lifted word for word from;

DC-8 Mishap on 12 Dec 1996 N827AX -Stall Recovery in Mountainous Terrain (http://www.apstraining.com/article9_fci_training_aug03.htm)

Flat spins start from normal spins as the spin develops. For a flat spin to develop from a normal spin you need a propellor blown elevator, (which we don't have on 447), and/or aft cg, (which we do). If the cg is aft enough the aircraft is perfectly content to stay in the flat spin all the way down. Inertia keeps the airplane in the spin. The tail section is not sized, nor configured, (rudder area below the HS), to recover A330's from flat spins. Engine departure will move the cg further aft, which is good for flat spins.

Note; Excuse my somewhat, what can be construed as, contrite responses, but I'm not one for words - try to say much in as few words as possible so as not to take up my, and my audience's, time. No intention of being condescending, respect the ones that deserve it, especially the pilots. Y'all are tops at what you do. Just trying to fill-in in places.

[takata]

Clear_Prop:
Is it possible that all the radio calls leading up to the incident were made using RMP2 up until the initial point of the scenario developing; and that thereafter the person operating RMP1 subsequently took charge of putting some emergency calls in, possibly on several occasions? With a rapidly developing situation and the knowledge that they were in the midlde-of-VHF-nowhere... can we rule out the possibiility that even in a controlled emergency descent, the crew may have overlooked a function check / repeat calls on RMP2, feeling that calls had been made as per procedure?

Hi,
Very good point, added to:
1. After landing in Brazil, May 31st, F-GZCP had radio issues: RMP1 had failed. The mech switched the panels with RMP3 which was left INOP for her return leg.
2. In case of double-engine failure, followed by EMER ELEC, only VHF1-HF1 would be available... via RMP1, if working?
3. The fairly bad weather around her in all directions, considering she would have to fly lower, may by itself account for a major issue when using comms.

[Litebulbs]

The temptation for any lay theory is to base it perhaps solely on what you know best. Currents, Wx, AB systems, AF, etc. etc. I have no specific field other than 40 years of flying. Weather is my worst fear, followed by IMC vs. visual, followed a long way behind by airframe and powerplant issues.

Do you believe weather brought this jet down, of that you fear that it might have?

[RobertS975]

Thus far, there has been no reported evidence of a fire on the aircraft... no residue on the wreckage or the victims. Nothing should be off the table as yet, but so far, nothing has been found to indicate a fire.

[PJ2]

takata;
Is it possible to ask you if you could compute how far could have glided F-GZCP following a double engine failure due to icing @ FL350 or close (~260 kts /210t), as you already suggested a long time ago (I took this very good point from you http://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/smile.gif), including a near 180 deg turn with max energy conservation? (I guess, at this point, the turn radius would have been much less important than the amount of altitude/speed wasted).
I believe I had earlier posited that the engines would have flamed out in a deep stall due to extreme angles of attack, not as a result of ice (as per the paper you kindly referenced), but as possibilities are being explored I can provide the following:

With the assumed loss of airspeed reference and assuming the "glide" scenario, the crew would be faced with selecting a speed at which to descend. This selection would be based upon whether an engine re-light was the strategy or if such an option were precluded, a glide and ditching. The speed and descent strategies are substantially different but the zero-wind distance covered is about the same.

For an engine relight, the optimum speed is 300kts, the pitch attitude for 210k kg 0.5ND; the QRH indicates that using this strategy, the aircraft would take about 15 minutes to descend from FL400 to ground and travel approximately 100nm

If the strategy is to glide with the intention of ditching, the optimum speed would be "green dot", which would roughly be, (for 210T) at 350, 238kts.

For this strategy, an average descent rate of about 1300fpm is indicated. Assuming a steady descent rate from, say, FL300 (5000ft lost in sorting things out), the time to touchdown would be 23 minutes and distance covered at about 4nm/minute would be just under 100nm.

In any turn, it obviously requires more lift to both glide and to provide energy for the turn, (slightly higher 'g'), so some loss of forward distance even without an increase in rate of descent, would occur. A reasonable estimate would be 5, possibly 10nm - it wouldn't be zero, and it wouldnt' be 20nm.

All these calculations are obviously based upon timely, correct assessment and handling with regard to the QRH numbers, and as such are "best cases"; any compromises or less than optimal performance obviously reduces distance covered and time to contact.
- Would it be possible for her to dump fuel if necessary after EMER ELEC? (keeping enough to restart engines and reach F. Noronha or Brazilian coast?) The A330 does not have a fuel dump system. The A340 does. - What would have been the odds for the RAT to supply power and to restart engines, considering the heavy rain possible at lower alt?
The RAT does not "supply power" to start engines at any time. It is a hydraulic pump of minimal capacity with a two-bladed propeller mounted in the #4 flap-track canoe on the right wing. It will only supply hydraulic power to the emergency electrical generator, which may be what you're referencing? :) Engine start is possible using bleed air from the APU but, as seen below, the APU is not started until reaching FL250 in the descent.

I know of some comments that indicated that the APU will start well above this altitude but there are only so many attempts in the batteries...

I wouldn't expect "heavy rain" to play a role in any starting difficulty (due to certification tests and absence of cautions for same in either the Engine Relight QRH checklist or the All Engine Flameout - Fuel Remaining QRH drill)

For the awareness of all, here is part of an example of an "All Engine Flameout - Fuel Remaining" QRH checklist:
RAT ......................................................MAN ON
– ENG START SEL.....................................IGN
– THRUST LEVERS................................... IDLE
– OPTIMUM RELIGHT SPD ......................... 300/.82

Increase speed during descent toward 300 knots. Do not exceed MMO
At 300 knots/.82 with all engines stopped it takes about 15 minutes to descend from FL400 to the ground. The distance is about 100 NM.
In case of a speed indication failure (volcanic ash): Pitch attitude for optimum relight speed is (list of optimal pitch attitudes)
– LANDING STRATEGY................................DETERMINE
Determine whether a runway can be reached or the most appropriate place for a forced landing/ditching.
– EMER ELEC PWR (If not automatically coupled) ..............MAN ON
– VHF1 ............................................................ .........USE
– ATC ............................................................ ...........NOTIFY
IF NO RELIGHT AFTER 30 SEC :
– ENG MASTERS..................................................... .... OFF 30S/ON
Unassisted start attempts can be repeated until successful, or until APU BLEED is available.
IF UNSUCCESSFUL :
– CREW OXY MASKS (above FL 100)................................ON
WHEN BELOW FL 250 :
– APU (if operative).................................................. ... START
WHEN BELOW FL 200 :
– WING ANTI ICE .........................................................OFF
– APU BLEED....................................................... .........ON
IN SEQUENCE
– ENG MASTERS (one at a time)..................................... OFF 30S/ON
When APU bleed is available or if engine restart is definitively considered impossible :
– OPTIMUM SPEED..............................................REFER TO TABLE BELOW
- What would be the risk of loss of control when restarting engines?It is not possible to determine the capabilities and level of discipline brought to bear by any one crew upon such circumstances. There is no inherent potential for "loss of control" in the drill nor in the relight of the engines, but flight conditions, further aircraft degradation, many possible sources of distraction would all have to be considered.
- In the paper about engine icing, they mentioned that engines would not restart above 10,000 ft, have you got an explanation for that?
Would the referenced quote from the paper (pg.2) be:
The engine speed decay was also associated with an increase of Turbine Gas Temperature (TGT) and a failure of the engine to respond to the pilot commanded thrust level, thereby, receiving the name “rollback”. Engines that were shut down from the sub-idle operating condition could be restarted at an altitude of about 10,000 feet Those engines not shut down recovered to normal operation at about the same altitude.The reference here is to smaller high-bypass engines in Commuter aircraft. The A330 QRH specifies the altitudes and speeds under which both air-start and assisted starts may be expected to succeed given all other factors being equal. I am familiar with the phenomenon of icing accretion on the backs of compressor blades, notably the N1 in large, high-bypass engines such as are on the A330 and in fact we were using a procedure to address "roll-back" at one point, possibly for other (bleed) issues.

In short, I have no explanation at all for the paper's statements partly because it references commuter aircraft but also because there is no mention of this in the QRH which would advise the crew to act or execute the drills differently, (by not expecting an engine start above 10,000ft, etc).

Hope this helps, takata. While I disagree for a number of reasons with the "glide" thesis we cannot discount it.

[HarryMann]

It seems rather sloppy text even in french. Surely it should say velocity or speed, since I don't see how it can be deduced whether or not the aircraft was accelerating at the time of impact

It has been pointed out earlier that engineers using this phrase in this way means 'deceleration' i.e. force (=ma)

due to impact at high speed.

It does not mean the acceleration was 'accelerating' :=

[Litebulbs]

The A330 does not have a fuel dump system. The A340 does.

I am not saying that all do, but our one's have. I have had the privilege of watching the system used in anger!

[PEI_3721]

Ref post 3193 {surplus 1}, this uses a similar ‘backwards’ deduction path as AstraMike {post 3179}, and then invokes some structural failure to maintain the spin. I haven’t seen any reference or evidence of structural failure, so how is this line of thought justified?

Returning to previous posts on the rudder limiter (maximum rudder deflection). The limit angle is a function of CAS and is computed by the SECs (A330 controls description). With a double SEC failure, the system freezes at the limit value. This condition may have been induced by the ADC faults / shutdown, but in the process of ‘failing’ due to parameter comparison, the ADC may have registered quite a low value of CAS. IIRC the comparator trips with a discrepancy greater than 60kts IAS. Thus, if the IAS value was low, then the rudder limiter may have frozen at quite a large angle; … perhaps a point for future reference.

[PJ2]

Litebulbs;
I am not saying that all do, but our one's have. I have had the privilege of watching the system used in anger!
You know, somewhere I recall someone saying that before, so thank you for reminding me. Ours didn't and I thought it was the design itself.

takata;

If the AF447 A330 had a fuel dump system, given the kinds of equipment powered (necessary for safe flight only), on the emergency electrical generator or the batteries, I would expect that no fuel dump capability would remain. Fuel dump is simply to reduce landing weight, but these aircraft are usually certified to land at MTOWs so fuel dump would not be an "emergency" item required for safe flight.

Sorry for misleading you and thanks to litebulbs.

[safetypee]

takata #3209, re engine icing / relighting. It’s not clear which engine type or ‘report’ you are referring too.
The initial section (Mason, Strapp, & Chow) reports on a medium sized regional aircraft suffering ‘rollback’. For this aircraft / engine combination, some engines did not relight easily as the severe ice accumulation took some time to clear; also, the relight envelope was below FL200. In some instances the subsequent stages of the compressor were damaged and engine did not relight at all, or ran sub-standard.
For the large commercial transport engines, the report indicates that initial ice accumulation did not generate engine problems, but the relatively smaller amount of ice passing through the compressor as the ice melted did, i.e. a problem when exiting the conditions. In general, the effects were mild and although the report describes the instances of shutdowns as ‘failure’, it qualifies this in that all engines were restarted, even when damaged.
Thus, the ice and engine failure scenario is unlikely.

[TyroPicard]

ClippedCub
You mentioned aft cg as leading to a flat spin... from the report the a/c was close to the forward limit on departure.

The balance corresponding to the aircraft’s takeoff weight and given on the definitive loadsheet (after LMC) was 23.3% of the MAC, for a forward limit of 22.7% and an aft limit of 36.2% at takeoff.

[BOAC]

TP - do you or PJ know where the assumed cruise CofG at "between 37.3 and 37.8%" sits with any limits? All the report says is 'within the limits'.

[BigFootDriver]

"the aircraft entered into a mesoscale Cb, it may have encountered moderate turbulences "

Huh??? Should read "it may have encounter extreme turbulences"

Punching holes in 55,000 foot TRW's will always produce way more than MODERATE turbulence.


Please join me in being scared of CB's above 30,000 feet.

BFD

[PJ2]

BOAC - the max aft cg that I show (and the 330 I'm pointing to may not be the same as the AF one), for 210k kg is just over 40% - fwd limit is under 17%. WRT TP's comments above, I show different slightly figures but the MTOW I'm referencing is around 230k kg and the AF 330 MTOW is 233k kg.

[BOAC]

So it looks as if it was 'aft' then. Are you aware of any 'guidance' on Cof G management on flights such as 447 had ahead of it? Weight-wise she appears to have taken off 243kg below max.

EDIT: to ask PJ if he has any observations on chosen level and speed. (I cannot find any determination of SAT deviation from ISA in the report.)


Please join me in being scared of CB's above 30,000 feet.- actually at any height. Going under a big one is not exactly fun and going through one below 30k, erm, no......

[wsherriff]

Although not known by the "Industry", the swept wing aircraft design is subject to a pitch-up, in a strong, weather induced up-draft! (Personal experience in a Boeing 707) Management explained it away by saying I was outside the "Envelope"!!

AF 447 may have survived if it had been left to the crew's natural physical sense inputs and normal, trained, control responses! The FBW programmed control inputs, in response to the pitch-up attitude, created a complex of rapid attitude transttions beyond the "Scope"!

We must standby until the computer nerds (experts) absorb some Aerodynamics knowledge!



































































9

[phoenix leader]

All seems very quite at the moment, but is there any news on the search for the "Flight Data Recorder" (Black Box) and if not has anynone any information as to the latest on the search for it?

[Dysag]

1) Yes, it is, quite.
2) No, not anynone.

[BOAC]

Not located as far as we know at 070720092104Z. I think most people assume the 'pinger' to be 'dead' due to the time factor and the chances of locating the tail section in the sea extremely remote. It would be a very lucky event if they found the metal.

Whether or not the search will continue...?

[takata]

@PJ2:
Thank you a lot for all those very detailed infos and for answering all my questions! You saved me many hours studying the FCOM Engine's Chapters as I was totally unfamiliar with this part of the aircraft.

I duely noticed that you had previously pointed an engine flame-out during a stall, but that stall would also imply a serious loss of altitude and much less distance could be flown after an eventual recovery. Nevertheless, 90-100 NM is fitting very well my bracket of [90-115 NM] corresponding to [0.40-0.50 m/s] drift speed from 0214? position in whatever direction (preferably to the Brazilian coast or F. de N.).

I was not suggesting that F-GZCP could have planned to ditch because it would be fairly suicidal by night and bad weather in the middle of the Atlantic, possibly without comms, and absolutely nothing is suggesting a single trace of preparation. So, I was wondering about a loss of control at low altitude during a desperate attempt to restart the engines, or a battery exhaustion...

I wondered also if an eventual TAT probes icing would not affect at some point the engine monitoring if a false and higher temperature would be delivered to the system. I have no idea of the consequences.

I'll study closely your answers and will re-read the engine icing documents. @Safetypee: thank you also for the complementary and very usefull informations.

S~
Olivier

[ClippedCub]

You mentioned aft cg as leading to a flat spin... from the report the a/c was close to the forward limit on departure.Modern transports are designed with supercritical, or aft loaded airfoils to give thicker airfoils, (more fuel volume and reduced structural wing weight), compared to conventional airfoils. Think of these airfoils as conventional but with 5 to 10 degrees of flap deflection. Even with the long moment arms of the tail of transports, there can be up to a 20 count drag penalty to trim the nose down pitching moment produced by the aft loaded, cambered sections, at cruise. To mitigate this drag penalty, designers will trim at aft cg positions at cruise using fuel transfer. The pilots here can expand on procedure, and whether they would have been at max aft cg accounting for fuel burn.

We normally reference aerodynamic conditions at 25% MAC, so cg's approaching 40% are pretty far aft. Don't think even aerobatic airplanes are operated at 40% aft cg, but will check.

Edit: For the Yak 54, cg can approach 37%, but their forward cg limit is 29%. Must keep it aft for maneuverability. Abbreviated paragraphs,

Personnel from the Yakovlev Design Bureau provided the following information: The airplane is rated for nine positive Gs, and seven negative Gs. It has a roll rate of 340 degrees per second. Yakovlev Design Bureau personnel reported that according to their flight test data, at an aft center of gravity (CG) of 37 percent mean aerodynamic chord (MAC), the airplane exhibited neutral stability, but was easily controlled. At a forward CG of 30 percent MAC, the stick force per G is 4 kg (8.8 pounds). At an aft CG (37 percent MAC), the stick force per G is 1 kg (2.2 pounds). The airplane has an aerodynamic buffet that occurs before a stall. The altitude needed to recover from an upright stall was 820 feet, and 984 feet for an inverted stall. The airplane did not demonstrate any tendency to enter an inadvertent spin during stall testing.
Additionally, Yakovlev Design Bureau personnel reported that upright and inverted spins were steep and stable. The angle of attack during a normal spin was 40 to 50 degrees, with a recovery in 1/2 turn. The altitude loss for a 3-turn spin was reported to be 1,969 to 2,133 feet. The altitude loss for a 6-turn spin was 2,625 to 2,789 feet. The load factors during spin recovery did not normally exceed 2.5 Gs. A flat spin had an angle of attack of 60 degrees, with 1 turn for recovery. The altitude loss during a 6-turn flat spin was 2,297 to 2,461 feet.


The AOA for normal stall can be reduced by relaxing back pressure slightly, but still keeping it stalled. Speeds rotation. Notice that even with low mass at the airframe extremities, it still takes one turn to recover from a flat spin. The Yak-52 takes 2-3 turns. An A330 with distributed fuel load and passenger/cargo load would be extremely difficult, if not impossible, to recover from a flat spin even with larger controls.

[Art-Deco]

Hi again.
Some reflections from a sat-ops (not a pilot).
Some people here think that the 30 second blackout in the ACARS-txm:s is related to a violent turning on the a/c-body.
There could be a much simpler explanation, ACARS works in microwave band and as the a/c passes some very dense cb:s, these ones has so much high damping factors that the link budget to the satellite is disrubted. I have work for years with disrubted satellite signals when a huge cb occurs, the damping factor has varied from 10-25dB depending on the clouds formation.

I have taken the Tim Vasquez erlier calculations and added the timeframe of the ACARS. As there was a 31 second lost carrier it should be possible to calculate the exakt size of the cb:s worst area, I got approx 6km with around 780km/h, -but I may have got the wrong speed of the a/c here.

I have noticed that the a/c should have kept a straigth course until it hit the real bad CB center to get a 31 second loss of ACARS-txm:, after that the a/C came out of the "black-spot" and the txm:s resumed. If the a/c after a minute started to make a hard right (east) move, it would make further txm:s hard as it then was on the border to a heavy cb with a lot of damping on the microwave L-band.

Enlosed is Tims erlier work that I used to plot the real-time acars pos.
The clouds may have a litte differnt shape as the sat-images were taken some minutes erlier. If you the compare the debree-map, it looks like it spread like rings on the water with a little drift.

Enclosing BEA:s ACARS LOG again to compare with the images below:

2:10:10 - .1/WRN/WN0906010210 221002006AUTO FLT AP OFF
2:10:16 - .1/WRN/WN0906010210 226201006AUTO FLT REAC W/S DET FAULT
2:10:23 - .1/WRN/WN0906010210 279100506F/CTL ALTN LAW
2:10:29 - .1/WRN/WN0906010210 228300206FLAG ON CAPT PFD SPD LIMIT
2:10:34 #0210/+2.98-30.59
2:10:41 - .1/WRN/WN0906010210 228301206FLAG ON F/O PFD SPD LIMIT
2:10:47 - .1/WRN/WN0906010210 223002506AUTO FLT A/THR OFF
2:10:54 - .1/WRN/WN0906010210 344300506NAV TCAS FAULT
2:11:00 - .1/WRN/WN0906010210 228300106FLAG ON CAPT PFD FD
2:11:15 - .1/WRN/WN0906010210 228301106FLAG ON F/O PFD FD
2:11:21 - .1/WRN/WN0906010210 272302006F/CTL RUD TRV LIM FAULT
2:11:27 - .1/WRN/WN0906010210 279045506MAINTENANCE STATUS EFCS 2
2:11:42 - .1/WRN/WN0906010210 279045006MAINTENANCE STATUS EFCS 1
2:11:49 - .1/FLR/FR0906010210 34111506EFCS2 1,EFCS1,AFS,,,,,PROBE-PITOT 1X2 / 2X3 / 1X3 (9DA),HARD
2:11:55 - .1/FLR/FR0906010210 27933406EFCS1 X2,EFCS2X,,,,,,FCPC2 (2CE2)
/WRG:ADIRU1 BUS ADR1-2 TO FCPC2,HARD
2:12:10 - .1/WRN/WN0906010211 341200106FLAG ON CAPT PFD FPV
2:12:16 - .1/WRN/WN0906010211 341201106FLAG ON F/O PFD FPV
2:12:51 - .1/WRN/WN0906010212 341040006NAV ADR DISAGREE
2:13 - .1/FLR/FR0906010211 34220006ISIS 1,,,,,,,ISIS(22FN-10FC) SPEED OR
MACH FUNCTION,HARD
2:13:14 - .1/FLR/FR0906010211 34123406IR2 1,EFCS1X,IR1,IR3,,,,ADIRU2
(1FP2),HARD
2:13:45 - .1/WRN/WN0906010213 279002506F/CTL PRIM 1 FAULT
2:13:51 - .1/WRN/WN0906010213 279004006F/CTL SEC 1 FAULT
:14:14 - .1/WRN/WN0906010214 341036006MAINTENANCE STATUS ADR 2
2:14:20 - .1/FLR/FR0906010213 22833406AFS
1,,,,,,,FMGEC1(1CA1),INTERMITTENT
2:14:26 - .1/WRN/WN0906010214 213100206ADVISORY CABIN VERTICAL SPEED


http://i832.photobucket.com/albums/zz243/art-deco/meteosatmockup.jpg



http://i832.photobucket.com/albums/zz243/art-deco/intolradar.jpg


http://i832.photobucket.com/albums/zz243/art-deco/vreck.jpg

[singpilot]

Page 18 of the prelim report references this situation. AF447 had a FCMS (Fuel Management System) that used a 'trim tank' to move CofG aft for cruise. This transfer begins in climb, and, as noted, keep target CofG within 0.5% of target MAC. 37.8% was the estimated aft CofG for this segment of the flight, and actual regulatory aft limit would have been 'behind' that.

[Will Fraser]

I will continue to await the synthesis of a straightforward analysis of the only important evidence that exists to date, and that having been actively ignored, the Forensic Pathology Report. Anyone satisfied with 'apparently well preserved' ? At some point in time, "we haven't seen the Data" must become "We refuse to look at it." There remains quite a disconnect between Brazilian reports inferring a breakup and BEA's "conclusion" of an intact a/c at impact.

[steamchicken]

Without intending to do so, I may have hyperfocused my disagreement with BEA terminology. In and of itself, the phrase en ligne de vol is reasonably benign. To take issue with it involves a very strict 'raison d'etre'. It may be a non charged description of horizontal for whomever wrote the piece. The writer isn't responsible, the group who approved the text is. As Surplus1 so eloquently points out, this report is composed by parties who have well defined and difficult to disguise interests in the ultimate understanding of the piece by all who read it. As such, it is a rehash of all the information already known, exclusion of information that would lay responsibility on an interested party, and is essentially useless.

Without substantiating a conclusion of hull integrity, they claim it by 'visual inspection'. No supporting engineering, no metallurgy, no independent or reviewed analysis. They rely solely on their authority to conclude to do so. This report is opportunistically political.


Your evidence of this appears to be: that you don't speak French very well. What would you have said about a Frenchman who made similar assertions about an FAA/NTSB report entirely because he didn't understand an unusual phrase in English?

[Will Fraser]

I would tell you that it wouldn't matter to me, both authorities have divergent missions from what is 'expected' by the public. Besides, it doesn't matter what I think, what do you think of it? My source as a non French speaking person is a phD in French linguistics, whom I trust completely. Steamchicken, if you read my quote (above) for comprehension, you will note that I have softened my initial reaction, and am giving BEA some room here, and for the reasons you state. But it isn't only en ligne de vol that is concerning. There is not a chauvinistic bone in my airframe, all are vulnerable to a healthy scepticism. Do you doubt there is an element of 'circling the wagons' here? I see it, for one.
WilyB- willdothat

[WilyB]

Will Fraser:

Please re-read page one of BEA's report.


SPECIAL FOREWORD TO ENGLISH EDITION

This interim report has been translated and published by the BEA to
make its reading easier for English-speaking people. As accurate as the
translation may be, the original text in French should be considered as
the work of reference.

This part may also be of assistance:


This document has been prepared on the basis of the initial information
gathered during the investigation, without any analysis and - given the
continuing absence of wreckage, the flight recorders, radar tracks and
direct testimony - without any description of the circumstances of the
accident. Some of the points covered may evolve with time. Nothing in
the presentation of this interim report or in the points that are raised
therein should be interpreted as an indication of the orientation or
conclusions of the investigation.

In accordance with Annex 13 to the Convention on International Civil
Aviation, with EC directive 94/56 and with the French Civil Aviation
Code, the investigation is not conducted in such a way as to apportion
blame or to assess individual or collective responsibility. The sole objective
is to draw lessons from this occurrence which may help to prevent
future accidents or incidents

[xcitation]

(page 18 of BEA AF447 prelim report, english version)

1.6.4 Condition of the aircraft before departure

On arrival of the Paris-Rio de Janeiro flight the day before the accident, the Captain reported a problem at the level of the VHF1 selection key on RMP1. The aircraft has three RMPs:
RMP1 on the left-hand side, RMP2 on the right-hand side and RMP3 on the overhead panel.
The ground engineer had switched round RMP1 and RMP3 to allow the aircraft to leave, in compliance with the regulations (departure covered by a MEL). The departure covered by this MEL item did not have any operational consequences.


The 3 Brazil ATC requests were not replied to and the VHF radio had been repaired prior to take off. Coincidence? Cockpit non-response is hard to believe as they were continuing radio comms made seconds earlier. ATC tried 3 times. Also no further AF447 VHF comms after this point for 30 mins (breaking the off radar 10 min report in SOP?).
VHF is triple redundant however if one fails how do you know unless you do a test? Perhaps the earlier MEL was incorrectly identified as RMP1 switch but was actually an issue with VHF1?

Only a minor item but I want to ensure all the valid data points on the table.

[ VHF radio description:
Each RMP (Radio Managment Panel) is associated with a particular VHF (Very-High-Frequency) Radio. RMP1 is associated with VHF1, RMP2 is associated with VHF2, and RMP3 is associated with VHF3. All VHF Radios can be tuned by each RMP. When the VHF Radio selected by the RMP is not associated with that RMP, the SEL Light on that RMP as well as the RMP associated with the VHF Radio illuminates. For instance, if RMP2 has selected VHF1, the SEL Lights on RMP2 and RMP1 will illuminate.]

[singpilot]

xcitation;

A careful read of the radio contacts section shows the last voice comms at 0153 was on HF radio with ATLANTICO. To include a SELCAL check. Normal procedure was to take (noisy) HF off of speaker/headset at that point. A voice only recall from ATLANTICO requesting TASIL update would not have been 'heard'. There has been no explanation as to why ATLANTICO did not use SELCAL again to get a response from AF447.

But all of this last comm was on HF, so any involvement with VHF was moot at that point.

Also, the 'usual' setup was that the F/O was doing all the comms, and the swapped 'control panel' was between station one (Capt) and station 3 (Overhead panel). Station 2 (F/O) was never involved with swap.

Hope this helps.

[einhverfr]

PJ2: My impression of the ice particle icing paper was that engines could not be restarted usually above 10k feet because of the time required for the ice blockages to clear. Note in the paper it mentions that engines that were not shut down recovered function at about the same altitude. So while I don't doubt that A330 engines could behave differently, I don't think that it necessarily follows that they would provide power at a much higher altitude.

[JD-EE]

HazelNuts39 (http://www.pprune.org/members/305001-hazelnuts39), "Does this help?"

Wow, yes. Thank you!

You mention forty degree angle of attack, too. That probably would interrupt ACARS transmissions or at least make them less likely to succeed. It also extends the search range more along the reverse path and to the West. (Takata has good points about the currents and drift that cannot be totally ignored.)

The extreme angle of attack still means 120 degrees (round numbers) of relatively safe turn in clear air in a minute. I suspect in turbulence the more conservative figures would be used. So we do end up with a small donut hole in the South through and South East portions of the region around 02:10:34's report.

The next serious question is whether or not they thought they had a reason to head backwards. I can think of many. But more experienced pilots would do better than my guesses and imagination. It MIGHT be simpler to presume they decided to go around the storm to the left at the last moment and banked sharply for as much as a 90 degree turn. That puts them 5 miles West at the end of the turn as well as 5 miles further North (sort of rounded upwards and kept at convenient numbers for a SWAG.) Then there are (at least) three more minutes to account for. Plotting those kinds of estimates along top of takata's data will probably help form better estimates. Since takata has the originals I hope this plotting is added and reposted. (chuckle - not that I'm about to swim out there and try to find the plane myself or participate in the effort. It just might help figure out what the pilots are likely to have done during the period they may have maintained control. There might be a dollop of education that can come from it. At least it might start to dispel what begins to sound like conspiracy theories by declaring some scenarios are flat impossible.)

JD-EE

[einhverfr]

HarryMann:

It has been pointed out earlier that engineers using this phrase in this way means 'deceleration' i.e. force (=ma)


Simple way to think about it:

Airplane is travelling down. It makes contact with the water which stops the fall. This causes upward acceleration (possibly to a zero vertical speed).

Strong vertical acceleration means a strong CHANGE in the vertical component of the velocity. It doesn't necessarily mean anything beyond that.

[Hyperveloce]

cruising at ~240m/s at FL350, which altitude loss would it take to approach ~290m/s ? -3000 ft ?
Jeff

[xcitation]

A careful read of the radio contacts section shows the last voice comms at 0153 was on HF radio with ATLANTICO. To include a SELCAL check. Normal procedure was to take (noisy) HF off of speaker/headset at that point. A voice only recall from ATLANTICO requesting TASIL update would not have been 'heard'. There has been no explanation as to why ATLANTICO did not use SELCAL again to get a response from AF447.

But all of this last comm was on HF, so any involvement with VHF was moot at that point.

Also, the 'usual' setup was that the F/O was doing all the comms, and the swapped 'control panel' was between station one (Capt) and station 3 (Overhead panel). Station 2 (F/O) was never involved with swap.

Hope this helps.


Thanks SingPilot.
I had missed that switch from VHF to HF.
So that closes the VHF MEL issue.

The controller debate will continue until hopefully procedures are improved. Clearly there was a breakdown(s) in the controller handover and all the checks and balances failed. Hard to beleive post 9-11 that a passanger transport can go AWOL for several hours and not raise a red flag with someone somewhere.

[p51guy]

Would it have mattered? After all of these days of searching, three hours is meaningless.

[FanAviation]

Hi ! I'm a newbie here so I read and don't write but...
"Strong vertical acceleration means a strong CHANGE in the vertical component of the velocity. It doesn't necessarily mean anything beyond that."
Absolutely! You've got it right It is a simple statement from a frenchman with a scientific background. We do not talk of "deceleration" that is a word barely used in sciences only in more standard french. May I add the BEA report is very careful. The sentence is noted twice:
p.40 under the header "synthesis of an eye -visual- examination". To a frenchman this too is very clear it means this is what we see (with all the limitations it implies to a frenchman at least) nothing else.
Then it says "the plane has probably (vraisemblablement)) hit the surface of water in flight line ("with" but the word is missing here) a strong vertical acceleration"
p.72 Where it has to be linked with the previous sentence ("the identified elements are coming from all parts -the whole?- of the plane") and it says "their eye examination (again!) show that the plane was not destroyed in flight -because pieces coming from the whole plane dislay the same pattern of mishapenness so they might have been still in the plane when it crashed- it looks like it hit the water surface in flight line -roughtly flat attitude- with a strong vertical acceleration.
..italics +underscore= my comments.
Hope this helps our non/ french speaking and not familiar with the french culture friends here.

[PJ2]

FanAviation;
Hope this helps our non/ french speaking and not familiar with the french culture friends here.
It helps me m'sieur, many thanks!

takata;
I was not suggesting that F-GZCP could have planned to ditch because it would be fairly suicidal by night and bad weather in the middle of the Atlantic, possibly without comms, and absolutely nothing is suggesting a single trace of preparation. So, I was wondering about a loss of control at low altitude during a desperate attempt to restart the engines, or a battery exhaustion...
You're very welcome. Re "not suggesting ditching", ah okay - misunderstood. Re loss of control lower down, yes, possible but given the statements about a clear vertical acceleration component such a scenario would take a lot of altitude to develop - so any "mishandling resulting in a stall" would not occur below, say, 10,000ft as there would still be significant, not slight, forward component at collision with the sea precluding the vertical descent scenario. Obviously the further away from 02:14:59 we are, the more exponentially broader the scenarios become.

PJ2

[Will Fraser]

Hi FanAviation. I appreciate your help, and would reply that where you can characterize what has been written in the report as an analysis, description of circumstances, or conclusion, then back up and read WilyB's post, especially the red part, and see if you see any contradictions between stated purpose, and text in fact. I see many analyses, descriptions of circumstance, and conclusions; the apparent conflict vis a vis purpose versus product is clear to me. I have merely stated that the text involving a report of the condition of the bodies recovered by the French team is gratuitous, unscientific, and irrelevent. It is also a "description" (a vague one) something they warn is not appropriate.

Will :ok:

[singpilot]

p51guy said...

Would it have mattered? After all of these days of searching, three hours is meaningless.

But can you imagine if AF447 had pulled a 'Sully' and landed/ditched reasonably intact, and there were actually survivors in the water?

Every moment of delay at that point could have mattered. 6 hours to launch a SAR plane from Brest, France to backtrack the route (another 9-ish hour flight), and then arrive at TASIL at midnight the next day.....

[SaturnV]

singpilot, annex 3 of the French version of the BEA report gives the last radio contact from AF 447 as occurring at 01:35:43, "-AIR FRANCE FOUR FOUR SEVEN, thank you"

AF447 was replying to Atlantico saying this at 01:35:38: "Acionamento do código SELCALL"

Is there another section of the BEA report that describes a subsequent radio communication from AF447 at 0153?

[HarryMann]

.. and getting a drift buoy in the water at approx last know position would have happened a lot sooner perhaps too?