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AF447

Old 6th Jul 2009, 19:22
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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....
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Old 6th Jul 2009, 19:40
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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

Last edited by takata; 6th Jul 2009 at 20:11. Reason: typos
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Old 6th Jul 2009, 19:43
  #3123 (permalink)  
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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.

Last edited by PJ2; 6th Jul 2009 at 19:56.
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Old 6th Jul 2009, 19:53
  #3124 (permalink)  
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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.
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Old 6th Jul 2009, 20:07
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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)!
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Old 6th Jul 2009, 20:09
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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.
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Old 6th Jul 2009, 20:23
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Originally Posted by woodvale
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.
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Old 6th Jul 2009, 21:01
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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.)
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Old 6th Jul 2009, 21:03
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CVR/FDR

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.
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Old 6th Jul 2009, 21:08
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drift hypothesis

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).



Last edited by takata; 6th Jul 2009 at 22:11.
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Old 6th Jul 2009, 21:08
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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."
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Old 6th Jul 2009, 21:25
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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.
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Old 6th Jul 2009, 21:28
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Originally Posted by 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'.
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.
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Old 6th Jul 2009, 21:35
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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.



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).





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



June 8.



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



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



The surface current between May 31 and June 4, centered on June 2


The surface current between June 5 and June 9, centered on June 7 (NOAA/NASA charts).


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.
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Old 6th Jul 2009, 22:02
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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.
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Old 6th Jul 2009, 22:10
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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.

Last edited by Hyperveloce; 6th Jul 2009 at 22:21.
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Old 6th Jul 2009, 22:21
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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.

Last edited by singpilot; 6th Jul 2009 at 22:21. Reason: spelling and phase of moon.
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Old 6th Jul 2009, 22:21
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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
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Old 6th Jul 2009, 22:24
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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
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Old 6th Jul 2009, 22:24
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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

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. [I can’t envision why the pilot would want to do the latter in scheduled operations. It does not compute.]

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 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. [If that didn’t happen, the aircraft would be considered ‘unstable’ and fitted with a stability augmentation device to restore the minimum stability required for the certification category.]

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

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 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.

Last edited by surplus1; 7th Jul 2009 at 00:21. Reason: Correct typos
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