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nitpicker330
30th May 2011, 09:49
Airbus and Boeing stall recovery now specifies:---

1/ Immediate action to Reduce AOA to un-stall the wing
Then
2/ Secondary action to increase thrust to recover energy levels back to normal.

They don't want the nose to pitch up further by the low slung engines and immediate action of maximum thrust is inappropriate.

alright jack
30th May 2011, 09:52
I don't think the flight deck would have been quiet enough to hear the airflow due to the amount of warnings being triggered . If you're ever been in an Airbus Flight deck the repetitive warnings going off is very mentally distracting and you are not always able to cancel all of them. :sad:

nitpicker330
30th May 2011, 09:57
I've spent way too much of my life in the cockpit of the 330 777 etc and believe me there is a big difference in noise levels over the speed range. 60 KIAS to 250 KIAS would be a lot quieter....

Maybe with all else going on their brains failed to process the info being heard by their ears? Tunnel vision brought on by significant stress..

DouglasFlyer
30th May 2011, 10:01
@aeromech3

Stall Warning in A330 (OM B 1.34.10):

STALL WARNING (No ECAM message)
An aural stall warning is triggered when the AOA is greater than a predetermined angle.
This angle depends on:
- The slats / flap position
- The Speed / Mach
- The F/CTL law (normal, alternate / direct)

costamaia
30th May 2011, 10:03
@ cwatters

PPL & SLF here...

Why wasn't full power applied?Wasn't it?
From the BEA 27 May report (http://www.bea.aero/fr/enquetes/vol.af.447/point.enquete.af447.27mai2011.en.pdf): (http://www.bea.aero/fr/enquetes/vol.af.447/point.enquete.af447.27mai2011.en.pdf%29:)
"At 2 h 10 min 51, the stall warning was triggered again. The thrust levers were positioned in the TO/GA detent and the PF maintained nose-up inputs."

"The altitude was then about 35,000 ft, the angle of attack exceeded 40 degrees and the vertical speed was about -10,000 ft/min. The airplane’s pitch attitude did not exceed 15 degrees and the engines’ N1’s were close to 100%."

aeromech3
30th May 2011, 10:06
Thanks DouglasFlyer, can I assume the side stick also vibrates (stick shaker) and therefore the warning could not be misconstrued ordinarily as a Hi speed warning?

shogan1977
30th May 2011, 10:06
HI Nitpicker, I address this question to you, as your posts have been the most comforting for this SLF. This is an honest question, with no hidden agenda:

Do you think the manner in which the stall alarm sounded as events unfolded (as I read it was silent except on three occasions at least one - if not two - of which was when the pilot acted correctly...) would have a detrimental impact on the reaction of many/most (airbus) pilots? Or in other words, under the same circumstances, do you think your reaction could have been negatively affected by the stall alarm resulting in pull back, rather than push forward?

fireflybob
30th May 2011, 10:18
Psychologists have established that when human beings get "max outed" the first sensory input their brains delete is that of hearing.

DouglasFlyer
30th May 2011, 10:19
@aeromech3

No - the only warnings you get are:

AURAL: Cricket and "STALL" (syntetic voice)
and
MASTER WARNING (light)

nitpicker330
30th May 2011, 10:27
The Airbus book says that whilst in Alternate or Direct Law to rely on any Stall warnings as they now are based on AOA only.

So you should carry out the approved Stall recovery actions as specified by Airbus and the Stall warning is valid.

They don't appear to have done so.............

Lemain
30th May 2011, 10:37
STALL WARNING (No ECAM message)
An aural stall warning is triggered when the AOA is greater than a predetermined angle.
This angle depends on:
- The slats / flap position
- The Speed / Mach
- The F/CTL law (normal, alternate / direct) Presumably 'speed' is IAS from a pitot/s (already stated to be iced or not functioning)?
What about g? g significantly alters the stall 'speed'. If the device that gives a stall warning depends on working pitots we have a potentially unsafe design. I'm not suggesting that was necessarily a factor in this case and no doubt the investigators will find out, if it is, but it doesn't sound like a sound design.

nitpicker330
30th May 2011, 10:48
The Aircraft went into Alternate law as a result of the iced pitot tubes.
In Alternate and Direct Law the stall warning is now based on AOA only as the computers recognize the IAS may be wrong ( amongst other things) .

Seems like a good fall back thing to me.

gulfairs
30th May 2011, 10:48
I am a little perplexed.
What has happened to the basic law of flight:

Attitude.
Power.
Trim.

Point the aircraft at zero pitch attitude,
apply cruise power
unload any stick force (trim)
and no matter what a cb throws at you it cannot sustain an over speed nor an under speed.

astonmartin
30th May 2011, 10:53
@nitpicker330: I thought you meant to say that it is only suitable to look up AOA values when in a routine situation. What I meant was that this doesn't help you in situations with extreme AOA.

jcjeant
30th May 2011, 10:53
Hi,

Maybe old but a shool case:
http://www.fss.aero/accident-reports/dvdfiles/US/1996-12-22-3-US.pdf

EXECUTIVE SUMMARY On December 22, 1996, at 1810 eastern standard time, a Douglas DC-8-63, N827AX, operated by ABX Air Inc. (Airborne Express) impacted mountainous terrain in the vicinity of Narrows, Virginia, while on a post-modification functional evaluation flight. The three flightcrew members and three maintenance/avionics technicians on board were fatally injured. The airplane was destroyed by the impact and a postcrash fire. The functional evaluation flight, which originated from Piedmont Triad International Airport, Greensboro, North Carolina, was conducted on an instrument flight rules flight plan and operated under Title 14 Code of Federal Regulations Part 91.

The National Transportation Safety Board determines that the probable causes of this accident were the inappropriate control inputs applied by the flying pilot during a stall recovery attempt, the failure of the nonflying pilot-in-command to recognize, address, and correct these inappropriate control inputs, and the failure of ABX to establish a formal functional evaluation flight program that included adequate program guidelines, requirements and pilot training for performance of these flights. Contributing to the causes of the accident were the inoperative stick shaker stall warning system and the ABX DC-8 flight training simulator’s inadequate fidelity in reproducing the airplane’s stall characteristics.

Safety issues discussed in this report include airplane stall recovery procedures for functional evaluation flights, stall warning systems, fidelity of the ABX DC-8 flight training simulator, guidelines and limitations for conducting functional evaluation flights, and Federal Aviation Administration surveillance of air carrier functional evaluation flight programs. Recommendations concerning these issues were made to the Federal Aviation Administration.

nitpicker330
30th May 2011, 10:54
Aston........Yes it's ok to look up for fun value where time permits.

Lemain
30th May 2011, 10:59
The Aircraft went into Alternate law as a result of the iced pitot tubes.
In Alternate and Direct Law the stall warning is now based on AOA only as the computers recognize the IAS may be wrong ( amongst other things) .

Seems like a good fall back thing to me. If the AoA system requires pitot input in order to compute the AoA and if the pitot(s) become iced otherwise non-operational the AoA figure will be wrong.

ekw
30th May 2011, 11:13
Seems the PF lost situational awareness and either thought he was pulling the aircraft out of a dive at full power - having discounted speed and altitude indications as being unreliable or, induced by experiencing negative G's on his shoulder straps and wild roll movements, thought he had rolled over and was flying upside down.

aeromech3
30th May 2011, 11:19
for Capn Bloggs, there was turbulence reported in the report before the climb phase of the report and also the cabin crew were advised.
Would appear that the stall warning trigger point was around the AOA 6 deg point from the report.
What I don't see clearly, is why for most of the decent flight regime down to sea level, the stall warning was not active continuously, can it be muted?
Without the sintetic voice "Stall" the difference between stall cricket and high speed clacker could be difficult to discern!

nitpicker330
30th May 2011, 11:22
Lemain....No, under Normal law the computers use all available info to determine the stall AOA. As written above.....

On AF 47 there was a discrepancy between the ADR's ( some or all iced pitots) which caused the FBW to revert to Alternate law along with the AP A/THR dropping off and a lot of ECAM's

During Alternate and Direct Law the computer reverts to only using AOA directly sensed from the AOA vanes to cater for just this scenario.

When the stall warning finally did sound it was real......

Capn Bloggs
30th May 2011, 11:23
In Alternate and Direct Law the stall warning is now based on AOA only as the computers recognize the IAS may be wrong ( amongst other things) .

Seems like a good fall back thing to me.
Good? Stall warning stops when the speeds are invalid? Great system. If the AoA indicates the wing is stalled, it should keep going, regardless of the speed.

nitpicker330
30th May 2011, 11:28
yeah Bloggs I agree with you. I guess Airbus thought an A330 wouldn't get that slow in the air!!
A simple thing to re program I would think.

It's still complicated though because as they fell toward the sea at <60 KIAS with a very high AOA they were in Alternate law and the speed should have had nothing to do with the stall warning activation. So it should still have sounded. Maybe the Flight Controls reverted to normal law after the probes thawed????

The more you read FCOM 1 the more you get confused!!

Time to close the book....

shogan1977
30th May 2011, 11:49
yeah Bloggs I agree with you. I guess Airbus thought an A330 wouldn't get that slow in the air!!
A simple thing to re program I would think.

It's still complicated though because as they fell toward the sea at <60 KIAS with a very high AOA they were in Alternate law and the speed should have had nothing to do with the stall warning activation. So it should still have sounded. Maybe the Flight Controls reverted to normal law after the probes thawed????

So are Airbus going to fix this ASAP? :confused:

astonmartin
30th May 2011, 11:51
Turkish Crash at Amsterdam was ex military, this other incident where a 737 crashed during the night in a turn where the cpat was pilot flying was ex mil.

Ex mil is not safer, or less safe.

nitpicker330
30th May 2011, 11:51
Bloggs:--

I've had another read of your post.

If all the Pitot tubes iced up evenly together and there was no immediate discrepancy between the 3 ADR's then the Flight controls may well stay in Normal Law and all protections would still work including Stall Warnings. Therefore if the speed is iced up slow you will get incorrect Stall warnings. Hence the warning in the QRH.

If however if there is a discrepancy between the ADR's the Flight controls will revert to Alternate Law and then the stall warning will only be based on AOA directly from the vanes. Hence the warning in the QRH to respect Stall warnings while in Alternate or Direct Law.

THE TRICK FOR THE PILOT IS TO KNOW WHICH LAW YOU ARE IN

ST27
30th May 2011, 11:52
Am I right in thinking that -10,000 ft/min is around 100kts down? In which case if their airspeed was <60kts a normal attitude would produce a very high AoA.

If so they may have a normal attitude displayed, unknown airspeed indication, and no stall warning. Perhaps only clue was high rate of descent which they might not have believed given normal attitude?

It's not clear if there was no stall warning while the aircraft descended. The BAE report only states that the stall warning was suppressed when they reached the peak of their climb, when the measured speed dropped below 60 kts, but started up again as the aircraft began to fall. The report does not say if the alarm stayed on or shut off.

The last recorded information was that they were moving at 107 kts ground speed, so depending on what direction the wind was blowing, they might have had sufficient forward speed for the stall warning to continue sounding for the entire descent.

shogan1977
30th May 2011, 12:01
Nitpicker330: THE TRICK FOR THE PILOT IS TO KNOW WHICH LAW YOU ARE IN

That's comforting.... especially when a "baby" is the PF, alone over the Atlantic in pitch black, during a major CB with icing and severe turbulence (?) and multiple alarms... :uhoh:

Tell me this could be averted or is everyone screwed in similar circumstances? :sad:

aeromech3
30th May 2011, 12:12
Extract from Report:
At 2 h 10 min 16, the PNF said "so, we’ve lost the speeds" then "alternate law […]".
Seems the PF's were aware of this change!

shogan1977
30th May 2011, 12:13
Are the Pilots of Air France 447 to Blame? - Plane Crash Forensics - Popular Mechanics (http://www.popularmechanics.com/technology/aviation/crashes/are-the-pilots-of-air-france-447-to-blame-5818769)

nitpicker330
30th May 2011, 12:16
It's happened before and they survived.

We don't yet know all the details of this accident, what the Pilots were thinking
or exactly what Law this Aircraft was in.

Indeed the whole Flight Control Law system is complicated and I'm not an expert in it..

I would expect that following this accident Pilots are even more aware of the problem.

DC-ATE
30th May 2011, 12:40
Indeed the whole Flight Control Law system is complicated.....

Indeed it is. So.....WHY are they building this stuff now-a-days? There wasn't anything wrong with the pilot having direct control of his/her aircraft. Automation rears its ugly head once again.

RansS9
30th May 2011, 12:43
Is there some problem in displaying AOA prominantly? Does this lead to some other disasterous scenario ?

If your first action in an emergency is AVIATE. If AOA is the single most important indicator of this...why bury it on page 7 of some subsiduary display ???

Yes good crew should be able to interpret the conflicting information presented to them as possibly occured in this accident. But why make it difficult ?

We all have our "Off-Days". Two days ago I put petrol in my diesel car...for the second time!?! I was distracted at the time by some idiot trying to park nearby. I was mortified. Not because of diesle in my car but because of such a stupid mistake which in a less forgiving enviroment (aviation) could have been disasterous.

Rob Bamber
30th May 2011, 12:49
Here's an observation which may or may not be relevant. The plane decelerated from horizontal Mach 0.82 to 107 knots over a period of 3 min 30s. By my estimate that is an average horizontal deceleration of around 0.1g.

It seems to me that, given no visual cues nor instrument readings, a pilot flying by the seat of his pants may interprete a pitch up attitude coupled with such a horizontal deceleration as level flight. Furthermore, lowering the nose would immediately decrease the horizontal component of deceleration, which the pilot may perceive confusingly as his nose pitching up (which is what it has been all along). Pulling back on the stick would return to the illusion of level flight, albeit with a stick operating "in reverse". (This is assuming the control sufaces are still capable of controlling the a/c.)

Note the report states "inputs made by the PF were mainly nose-up", (my italics) and in its 3D diagram the descent appears to consist of straight lines.

wafelbolletjes
30th May 2011, 12:58
Does anyone know the exact flight route for AF447?

goldfish85
30th May 2011, 13:04
Quote: According to the BEA report, the AOA was indicated at 4 degrees as they went over the top. Since this is the primary driver of the stall warning, the warning would likely have shut off, no matter what the speed was, and even if they didn't disable it a low speed.

This is interesting. In researching FBW accidents for a presentation to ISASI, there was an A-340 (with similiar control laws) that triggered Angle-of-attack protection during cruise at FL360 over the north Atlantic. Once AoA protection is invoked, zero stick input will cause the airplane to maintain alpha-prot (about 4 something AoA). Since AoA at cruise is about 1 degree, this will result in a zoom. In the A-340 case, it zoomed over 2000 ft before the pilot could recover.

Now I know the airplane was reported to be in alternate law (AoA protection not available), but I would still wonder. I think we need to let BEA figure all this stuff out.

One more thing. There have been references to the NWA B-727 which departed KJFK with the pitot heat off. This was a colleague of mine and, at the time, I wondered "how could he be so dumb?" Well a year or so later, I found out just how dumb on can be. When all sorts of contradictory information is present from various failures, it is very easy to latch onto one conclusion and only see those facts that support that conclusion and ignore those that don't.

Capn Bloggs
30th May 2011, 13:09
Also don't blame the THS trimming up to 13 deg nose up. It was a result of the Pilots demanding back stick pitch up ( to counter what they thought was an overspeed ) the speed obviously decayed during the manoeuvre requiring more and more trim to help it satisfy the Pilots demand.
Sounds good in theory/normal operations but goes against the normal rules of flight, being if you pull back the system resists until you make the conscious effort to trim into the pull. If you let go without trimming, the nose goes back to where it was (or at least tries to).

In this case, the system trimmed full nose up and stayed there. That doesn't sound like a good idea to me and wouldn't have helped any nose down recovery effort by the crew, at least in the initial bit at the top of the zoom. They wouldn't have had to hold in a shedload of forward stick to get the thing to start trimming nose down.

barit1
30th May 2011, 13:21
30+ years ago I read an announcement of the Rosemount company developing a self-actuated Pitot heat system; it consisted of a vibrating reed in the airflow. If ice builds on the reed, it changes the natural frequency of vibration, and this frequency shift activates the ice protection.

Does anyone know what became of this system?

nitpicker330
30th May 2011, 13:26
Bloggs......Hang on a sec, on a normal aircraft if you thought you had an overspeed and pulled back on the stick you would most likely also trim back to assist as well.

In this case as the Pilot demanded nose up as the speed decayed it trimmed full up and stayed there most likely because the Pilots never pushed the stick forward during the stalled free fall from 38,000 feet so the Flight Control computers didn't see the need to trim forward either......

If they had applied full forward Sidestick in an attempt to un stall the wing then the stab would have moved forward to assist. It seems they not only didn't push forward they pulled back.

DouglasFlyer
30th May 2011, 13:30
@barit1
Todays pitot heat are usually auto/on by default. Airbus have the pitots heated low on ground as long as one engine is running and normal in flight mode. There's a switch to go from AUTO to ON for PROBE/WINDOW HEAT.

edga23
30th May 2011, 13:34
If I remember correctly those Air Caraibes guys who managed their loss of speed indication, also had the good idea to throw that switch from AUTO to ON and that probably helped to regain correct speed indications

aeromech3
30th May 2011, 13:35
@barit1
The device you describe would be an ice detector which on some aircraft would bring on a warning only.

MountainSnake
30th May 2011, 13:36
IMO it's just plain stupid that a multi-million machine with humans inside have to rely on a "stupid" analog tiny tube, even worst without redundancy or a reliable alternative.

DouglasFlyer
30th May 2011, 13:42
If you're about to invent something better than a pitot-tube you'll be a rich man. Even the space shuttle measures its speed with pitots while in the atmosphere...

fireflybob
30th May 2011, 13:43
Aircraft have been flying around for decades with pitot tubes which haven't iced up - how come there's been a problem with these ones?

jcjeant
30th May 2011, 13:56
Hi,

Aircraft have been flying around for decades with pitot tubes which haven't iced up - how come there's been a problem with these ones?

It's not new ....

Décembre 1995 : TFU 34.13.00.005 (annexe 1). Airbus fait le constat de l’insuffisance de la
certification des sondes Pitot. Les cristaux de glace obstruent les sondes ce qui provoque une
dégradation sévère du calcul des paramètres de vol.

December 1995: TFU 34.13.00.005 (Annex 1). Airbus made the finding of inadequate
Certification pitot probes. Ice crystals obstruct the probes which causes
severe degradation of calculating flight parameters.

Sober Lark
30th May 2011, 14:03
Would there be a forum such as this if we truly believed in being cautious in interpreting findings until all relevant information has been examined?

maynardGkeynes
30th May 2011, 14:06
I am a little perplexed.
What has happened to the basic law of flight:

Attitude.
Power.
Trim.

Point the aircraft at zero pitch attitude,
apply cruise power
unload any stick force (trim)
and no matter what a cb throws at you it cannot sustain an over speed nor an under speed. Using the standard practice of pitch + power to maintain safe flight does not work if the aircraft is ALREADY stalled, which was the case here.

costamaia
30th May 2011, 14:14
@ RobBamber

It seems to me that, given no visual cues nor instrument readings, a pilot flying by the seat of his pants may interprete a pitch up attitude coupled with such a horizontal deceleration as level flight.

Didn't the PF acknowlege reaching level 100?

Quote from http://www.bea.aero/fr/enquetes/vol.af.447/point.enquete.af447.27mai2011.en.pdf:

At 2 h 13 min 32, the PF said "we’re going to arrive at level one hundred".

That's roughly 25000' from the level 2 min before (350):

"At around 2 h 11 min 40, the Captain re-entered the cockpit. During the following seconds, all of the recorded speeds became invalid and the stall warning stopped.(...) The altitude was then about 35,000 ft, the angle of attack exceeded 40 degrees and the vertical speed was about -10,000 ft/min. The airplane’s pitch attitude did not exceed 15 degrees and the engines’ N1’s were close to 100%. The airplane was subject to roll oscillations that sometimes reached 40 degrees."

ST27
30th May 2011, 14:16
Here's an observation which may or may not be relevant. The plane decelerated from horizontal Mach 0.82 to 107 knots over a period of 3 min 30s. By my estimate that is an average horizontal deceleration of around 0.1g.

The aircraft pitched up steeply and decelerated from cruise speed to a virtual standstill in the first 30 seconds or so, then went from about 80 mph up to over 100 mph down. None of that would have been interpreted as normal horizontal flight.

Kiethf
30th May 2011, 14:45
The Guardian has cut ‘n pasted directly from an earlier post in this thread.... Air France crash inquiry details pilots' battle for survival | World news | The Guardian (http://www.guardian.co.uk/world/2011/may/27/air-france-crash-inquiry) Attributed to "Anonymous A330 Pilot”

A37575
30th May 2011, 15:08
Judging from the reports of what happened in the cockpit, one is left with the impression that without automation both pilots were seemingly bemused at events and helpless. This is not surprising, since with many airlines basic instrument flying ability has been relegated to low priority in favour of competency at autopilot operation. Even Jet Upset training is not a serious subject in simulator training. Five minutes at the most and once a year is the norm.

stepwilk
30th May 2011, 15:36
Unless I missed it, nobody seems to have mentioned that the original worst-case theory--that the airplane flew into the mother and father of all ITCZ thunderstorms because it was radar-blanked by a line of cells between it and AF447--no longer seems to hold water.

Certainly 447 flew into weather that created an unusual kind of supercooled, high-altitude icing that suddenly affected the Pitots, but the CVR transcript doesn't mention anything that might be interpreted as turbulence upset--only the apparent impossibility of dealing with multiple fault warnings and anomalous displays.

Graybeard
30th May 2011, 15:48
Seems like too much pilot training is spent on understanding five control laws: Normal, Alt 1, Alt 2, Direct, Abnormal. Are there more?

Makes me wonder if more than two are needed or desirable: Normal and Direct. I don't understand why the AP/AT had to drop out of Normal for flaky airspeed. At least not in cruise. It could hold pitch and power for awhile without dropping out, giving the pilots time to analyze the situation without having to hand fly, too.

Right Way Up
30th May 2011, 15:52
In the sim if all the pitots are iced at the same rate the aircraft will stay in Normal Law as there is no disagree. In a climb the aircraft will eventually overspeed and an nose up input made leading to an uncontrollable climb leading to a stall and very low airspeed. Not a very pleasant scenario.

Flight Safety
30th May 2011, 16:08
Why would the stall warning be programmed to stop if the AOA indication is deemed unreliable below 60kts? Doesn't it seem intuitive that if a 200t jet transport has an IAS of < 60kts (and WOW says the plane is in the air), then it MUST be stalled, regardless of the AOA reading?

Then again, we have our iced pitot scenario, with IAS of less than 60kts.

GeraldT
30th May 2011, 16:10
New article on Der Spiegel in english, including a quote from captain Dubois after entering the cockpit, that was not in the BEA-report, but comes from sources close to the investigation team.
Doomed Flight AF 447: Questions Raised about Airbus Automated Control System - SPIEGEL ONLINE - News - International (http://www.spiegel.de/international/world/0,1518,765764,00.html)

Flight Safety
30th May 2011, 16:18
Right Way Up, about as likely as 3 engines failing at the exact same time in the exact same way, not very likely.

Garrison
30th May 2011, 16:35
"The aircraft pitched up steeply and decelerated from cruise speed to a virtual standstill in the first 30 seconds or so, then went from about 80 mph up to over 100 mph down. None of that would have been interpreted as normal horizontal flight."

There is some confusion among posters here, and in the press, about the flight path. The pitch attitude is reported to be around 15-16 degrees nose up, and the angle of attack to be 35-40 degrees. This translates to a flight path angle of -20 to -25 degrees. If the vertical speed is around 10,000 fpm (~100 knots), then the slant speed has to be the vertical speed divided by the sine of the descent angle, or somewhere around 250 knots. This is the true airspeed. The airplane was not fluttering down vertically like a leaf, and its foward speed was not 60 knots or 107 knots or whatever. As the flight track graphic in the interim report (vertical dimension exaggerated) shows, it was in a stalled glide with a comparatively moderate angle of descent and a good deal of forward speed.

ChristiaanJ
30th May 2011, 16:38
But nothing is as fast for a basic instrument scan as an altimeter pointing at 12 o'clock and the VSI at 9 o'clock. Instant awareness of your altitude and sink rate.
IMO the tape display, while nice with the low and high speed buffet tapes on the airspeed, cannot compare to the rapid awareness you have with round dials and moving needles.Slightly O/T....
I agree with your basic remarks.... Not for nothing do glass engine instruments still show replicas of the original 'clocks'.
But the altimeter is a bad example, with the old "hours-minutes-seconds" clock scale (you know what I mean) not being all that fast and easy to read, and being implicated in several incidents (I don't remember accidents off-hand). Which is why the numerical 'drum' scale was added, even before we went to 'glass'.
Unfortunately, with the conversion to 'glass', just about all the moving pointers disappeared.

Humans are analog oriented.... For all the non-pilots on here.... just try to imagine playing a video game where all the game information is in the form of numbers on the screen.....

Lemain
30th May 2011, 16:47
Doesn't it seem intuitive that if a 200t jet transport has an IAS of < 60kts (and WOW says the plane is in the air), then it MUST be stalled, regardless of the AOA reading?
No, it is just as likely (or more so) to be an instrumentation error.

Montgolfier
30th May 2011, 17:16
I absolutely do not wish to start an Airbus v. Boeing thing - no interest in playing manufacturer top trumps at all.

However, I would be genuinely interested to know if and how this accident scenario might've been different - in terms of aircraft behaviour and what the pilots were presented with - if the aircraft involved had been one of Air France's 777s rather than one of their 330s?

Specifically in terms of autopilot/autothrust disconnection, stall warning being silenced <60KIAS, lack of AoA information, trim issues? Do you think the 777 would've been a more helpful/intuitive aircraft to grapple with in those desperate moments?

Again, not trying to stir it, just interested to know how much the aircraft type and design philosophy is to blame here (if at all) and if an alternative design might've helped those guys more...

Herod
30th May 2011, 17:27
Didn't some Airbus fanatic write a book in which he said of Sullenberger's accident "It was the aeroplane that saved them. It cradled them all the way down to the river." Has he said anything about this accident?

Guildenstern
30th May 2011, 17:32
I'm a scientist, not a pilot.

It seems that the biggest source of uncertainty is what did the pilots know and what was their assessment of the situation.

There seems to be a lot of debate as to whether they were aware of or had reliable data about speed, pitch, aoa, etc. But, we know that they were aware of their altitude and rate of descent as they passed through 10,000 ft. Even so, they continued to pull back on the stick. Is it possible that they believed they were in a steep dive rather than a stall?

Is it possible to get a stall warning when pulling out of a dive?

Isn't a dive is more recoverable than a stall? With "no other indications" is it not possible to fool oneself into believing the more hopeful scenario?

DozyWannabe
30th May 2011, 17:43
I don't understand why the AP/AT had to drop out of Normal for flaky airspeed.

Because without that information, some of the protections can't work. Any protection out is an immediate drop to Alternate Law 2, which puts the pilots in near-absolute command of the control surfaces (any remaining protections can be overridden with sufficient control deflection).

It may surprise many, but it was part of the original specification for the systems that drive the A320 and her descendants that if, for whatever reason, the computers think they can't behave as they should, they defer to the pilots - on the understanding that they have more information available to them, especially in daylight when there's an external reference as to which way is up. The human brain can at least try to work with partial information to rationally attempt a solution to the problem at hand, whereas a computer can't.

Also, I think you may be getting the FCU (Flight control unit - i.e. the FBW part of the design) confused with the FMC (aka A/P and A/THR), which is much like that of a conventional airliner).

At least not in cruise. It could hold pitch and power for awhile without dropping out, giving the pilots time to analyze the situation without having to hand fly, too.

This would add unnecessary complexity to the system. In fact the A/P can be engaged again in Alternate Law, but with airspeed data out, it's not considered a good idea. I know I keep harping on about this, but if you look at the Birgenair 757 incident, you can see what happens when an autopilot tries to fly the aircraft with a blocked pitot tube (and that was on a calm night, with little or no convective activity for miles).

I've lost count of the number of times I've heard "Switch the damn computers out and give control back to the pilots", or words to that effect. That is *exactly* what happened in this case. Unfortunately, with no airspeed data over water in the middle of the night and threading their way through patches of very inclement weather, even the best and most experienced pilots can be overwhelmed.

Elledan
30th May 2011, 17:45
The main issue seems to be the uncertainty about the human factor, it appears. For that we'd need to hear the entire CVR contents to draw any conclusions. I'm quite sure there is a lot of stuff on there which would be immensely helpful, but which we are unaware of at this point.

FDR plots would be nice too, of course :)

jcjeant
30th May 2011, 17:58
Hi,

But, we know that they were aware of their altitude and rate of descent as they passed through 10,000 ft
Even so, they continued to pull back on the stickWe know ?

wallybird7
30th May 2011, 18:10
"For the umpteenth time, there is no evidence the crew flew through a Cb. In fact, based on the last BEA report, the crew knew very well what was coming,weather-wise as they turned to avoid and briefed the cabin crew.

Had they then encountered mod or severe turb in the top of a Cb, I'm sure the BEA would have mentioned it."

NO EVIDENCE OF THUNDERSTORMS? IN A MAX WEIGHT CONDITION BARELY ABLE TO KEEP LEVEL AT 35,000 THE PLANE SUDDENLY ZOOMS UP TO 38,000' AT THE SAME TIME ALL THE BELLS AND WHISTLES START GOING OFF DUE TO FROZEN PITOT TUBES -- WHAT ELSE WOULD MAGICALLLY CAUSE THIS?

EVERY ONE ELSE IN THE AREA DEVIATED EXCEPT THEM. WHY?

IT IS ALSO WELL DOCUMENTED THAT A LARGE LINE OF CBS WERE DEAD AHEAD.

learner001
30th May 2011, 18:13
ChristiaanJ: But the altimeter is a bad example, with the old "hours-minutes-seconds" clock scale (you know what I mean) not being all that fast and easy to read, and being implicated in several incidents (I don't remember accidents off-hand). Which is why the numerical 'drum' scale was added, even before we went to 'glass'.

The addition of the 'drum' scale to a single pointer was a good thing. But that is where the improvement should have stopped. Removal of the 'last' pointer completely degraded the 'altitude trend situational awareness'. Especially on a rough ride...

ChristiaanJ: Unfortunately, with the conversion to 'glass', just about all the moving pointers disappeared.

So, to close the circle again, for the removal of the 'trend situational awareness' the trend vector was 'invented'... euhh...? Which 'as such' is a nice additional feature to have... Not as a replacement...

GlueBall
30th May 2011, 18:14
At 2 h 10 min 51 , the stall warning was triggered again. The thrust levers were positioned in the TO/GA detent and the PF maintained nose-up inputs

The Flight Data Recorder recorded airspeed and altitude as displayed on the left primary flight display (PFD), and on the integrated standby instrument system (ISIS).

"There was an inconsistency between the speeds displayed on the left side and the integrated standby instrument system (ISIS). This lasted for less than one minute."

Even if the pilots were confused about momentary airspeed deviations and had no longer trusted the displayed airspeeds: It's a mystery as to why the Pilot Flying would pull back on the stick and climb from FL 350 to FL 380 during multiple stall warnings. Elementary, basic flying instinct learned from day one in flying school, should have made him do just the opposite. That is, to get the nose down, not up during a stall warning.

Curiously, the captain in the Colgan Air DH-8 crash in upstate New York had also pulled back on the yoke during the stall warning and active stick pusher...

Inexperienced pilot graduates from the same school...? :{

bearfoil
30th May 2011, 18:15
To override the NU of the THS, in Alternate Law, one pulls back on the SS.

Yes? Was there confusion about the origin of the chronic NU on the way down?
I would assume so. To clear this, does one pull back to the stop and release?

"during" and "continuous" mean different things, yes?

If the cg was even partially ng, could the PF have confused the a/c insistence on climb with a 'stuck' "Law" command? One which he continually tried to 'Clear'? With intermittent full back ss to override??

see touch 'n oops below

Touch'n'oops
30th May 2011, 18:18
nitpicker330 BACK TO THE BOOKS.

For someone who is "supposed" to know their aircraft, you really do spout a load...

Alternate 1
Alternate 2
What is that supposed to mean???

Don't you mean:
Alternate WITH protections
Alternate WITHOUT protections

AUTOTRIM IS AVAILABLE IN ALTERNATE LAW TILL GEAR DOWN WHEN FLIGHT CONTROL LAW TRANSFERS TO DIRECT!!![/COLOR] :D

AUTOTRIM IS NOT AVAILABLE IN DIRECT AND MECH BACKUP.

NOW LEARN YOUR **** BEFORE YOU START BASHING OTHERS!!!

YOU MUST BE WELL KNOW FOR BEING A RIGHT ONE AT YOUR COMPANY :rolleyes:

ap08
30th May 2011, 18:26
We know ?
We know almost nothing. So little data has been made public that making any assumptions and conclusions is quite premature, if not simply stupid. Nothing can be said for sure without going through the entire CVR transcript, while at the same time looking at the FDR data.

I have an unrelated question. One of the error messages transmitted by the aircraft was
NAV TCAS FAULT (2 h 10)
Meaning: This message indicates that the TCAS is inoperative.

Is there any explanation why TCAS would fail? It seems completely unrelated to airspeed...

Guildenstern
30th May 2011, 18:31
@jcjeant - I'm just going by the bea rpt. The PF says "we're going to arrive at level one hundred." The report also says "the inputs made by the PF were mainly nose-up." It doesn't say that the last, simultaneous, inputs were nose down, so I assume they were nose up.

Still, my question is whether they might have thought they were in a dive?

barit1
30th May 2011, 18:31
Guildenstern:Is it possible to get a stall warning when pulling out of a dive?


Absolutely.

It's called "high speed stall" or maybe "accelerated stall", and it occurs any time you're asking the wing to work beyond its max CL. The attitude of the aircraft is immaterial.

In fact, what we usually call a common stall (1.0 g) is a special case; in general a stall occurs whenever (mass x g) exceeds the wing's aerodynamic lifting capacity.

ST27
30th May 2011, 18:32
There is some confusion among posters here, and in the press, about the flight path. The pitch attitude is reported to be around 15-16 degrees nose up, and the angle of attack to be 35-40 degrees. This translates to a flight path angle of -20 to -25 degrees. If the vertical speed is around 10,000 fpm (~100 knots), then the slant speed has to be the vertical speed divided by the sine of the descent angle, or somewhere around 250 knots. This is the true airspeed. The airplane was not fluttering down vertically like a leaf, and its forward speed was not 60 knots or 107 knots or whatever.

There is ample opportunity for confusion, since at different points in the report ground speed, AIS, and the erroneous speeds on the displays are mentioned. To understand what they are saying you have to keep the context of each separate in your mind.

As far as the forward speed, it was 107 knots when last recorded, according to the report. I assume that's GPS derived, so it should be accurate. However, that was ground speed, not the speed through the air. For your 250 knot estimate of airspeed to the true, that would imply a headwind speed of around 120 knots, which is unlikely. It was a thunderstorm, not a category 4 hurricane.

The report also mentions that the AOA in the final moments of the flight was always in excess of 35 degrees. It did not say how high it reached, nor what it was at the end of the recording. Thus, your assumption of only 40 degrees is probably an underestimate.

To put a perspective on it, if the wind was calm, then the actual flight path would be about 45 degrees down, AOA of about 61 degrees, with an actual speed through the air of about 151 knots.

Shaka Zulu
30th May 2011, 18:43
As for TCAS failing: might be completely unrelated to events. We sometimes have it momentarily failing in the CRZ and then rapidly coming back soon after.
However (speculation) it could be due to enormous amount of static (St Elmos) around the direction sensing receiving antenna etc.

In the grand scheme of things it's completely irrelevant to proceedings.

There but for the grace of God.

fireflybob
30th May 2011, 18:44
ok you're in the cruise and the pitots ice up. airspeed/mach will stay at current values. Crew decides to reduce to turbulence speed., thrust reduces to achieve this. As actual a/c speed reduces autopilot starts to slowly pitch the nose up to maintain altitude and whilst doing so applies nose up trim. Maybe the thrust even reduced to idle at this point.

This continues until ths is at aft limit (remember the indicated speed/mach are still at original cruise values but the actual aircraft speed is much lower. Autopilot and autothrust disengage and a/c reverts to Direct law giving immediate pitch up due trim and a/c gains circa 3,000 ft and then enters dynamic stall. Presumably this zoom would give a slight reduction in static pressure, therefore the indicated speeds would increase.

The aspect that really interests me is that neither crew member noticed the increasing pitch attitude as the speed was reducing. What would the flight director be commanding throughout all this? If during the zoom upwards it's showing fly down to regain the selected flight level this might explain the initial side stick forward to regain.

If neither pilot wasn't paying any attention to the attitude then where were they looking?

Coming back to the issue of pitots getting iced up I still don't understand with modern design why this is a problem. There are plenty of other jet transports flying around the world where, as far as am aware, this has never happened. What is intrinsically different in the design of the system on this a/c?

SoaringTheSkies
30th May 2011, 18:44
one of the things we learn in primary flight school is "hazardous attitudes". One of them is, iirc, "that can't happen to me". I read a lot of that one between the lines here. Scary.

I am fairly certain that either of the three pilots on board knew, at least in theory, how to recover from a stall.

btw: has anyone ruled out severe icing on the wings and stabilizers?

DozyWannabe
30th May 2011, 19:08
Is there any explanation why TCAS would fail? It seems completely unrelated to airspeed...

TCAS needs to know how fast they're going. If it doesn't it only has half the information (i.e. where they are) required to transmit .

Right Way Up
30th May 2011, 19:10
Flight Safety
*
Right Way Up, about as likely as 3 engines failing at the exact same time in the exact same way, not very likely.


Not sure why not as icing is likely to affect all pitots at the same time. With regard to engines failing its worth looking up the Miami- Nassau Tristar or the Royal flight 146!

wallybird7
30th May 2011, 19:25
"Unless I missed it, nobody seems to have mentioned that the original worst-case theory--that the airplane flew into the mother and father of all ITCZ thunderstorms because it was radar-blanked by a line of cells between it and AF447--no longer seems to hold water.

Certainly 447 flew into weather that created an unusual kind of supercooled, high-altitude icing that suddenly affected the Pitots, but the CVR transcript doesn't mention anything that might be interpreted as turbulence upset--only the apparent impossibility of dealing with multiple fault warnings and anomalous displays. "

Does anybody really believe that there wasn't a lot of chatter going on in the cockpit? Especially, "What's it doing now?"

We've been given only minimal information and so far no indication that the CVR was not intact.

Another notable absence: Any reference whatsoever to the number one item: THE CHECKLIST! With everything going "off " nothing re "reset".

concernedpassenger
30th May 2011, 19:27
Doomed Flight AF 447: Questions Raised about Airbus Automated Control System - SPIEGEL ONLINE - News - International (http://www.spiegel.de/international/world/0,1518,765764-2,00.html)

Gerhard Hüttig, a professor at the Institute of Aeronautics and Astronatics at the Technical University in Berlin, considers the high angle of the horizontal stabilizer to be a failure of the Airbus' electronic flight control system. Hüttig, a former Airbus pilot himself, calls it "a programming error with fatal consequences."

"No matter how hard the crew tried to push down the nose of the aircraft, they would have had no chance," Hüttig says. He is demanding that the entire fleet of Airbus A330s be grounded until the phenomenon is adequately explained.

Shaka Zulu
30th May 2011, 19:35
@DozyWannabe. TCAS doesn't receive any speed input whatsoever. It calculates closure rates based on comparing time it takes to send a signal and receive it back at the antenna.

Post amended because of bad wording

TCAS does have one air data input for Mode C (barometric altitude) coming from the Static Port. It would be very unusual for a Static Port (which is flush on the fuselage) to ice over.
So as a source of failure for the TCAS I think not likely.

DozyWannabe
30th May 2011, 19:48
@DozyWannabe. TCAS doesn't receive any speed input whatsoever. It calculates closure rates based on comparing time it takes to send a signal and receive it back at the antenna.
No Air Data Input.

I stand corrected - cool.

Right, so that being the case there are two questions. If TCAS doesn't require air data itself, is the way it's plumbed into the A330's avionics something to do with it? Also, at what point in the ACARS sequence did that message fire? Early on, it might raise some questions. Later, as more systems began to fail it might be a moot point.

aeromech3
30th May 2011, 19:53
TCAS computation needs altitude to assess threats and should receive barometric and Radio Altimeter inputs! yes/ no?

4Greens
30th May 2011, 20:19
For those pondering lessons from this accident:

Its probably been said before in the last 55 pages but,

If you lose sensible airspeed and altimeter indications, disregard all and fly attitude and zero bank angle for normal cruise flight with relevant manual throttle setting. Been there, done that.

Try it in the sim.

Zorin_75
30th May 2011, 20:19
Autopilot and autothrust disengage and a/c reverts to Direct law giving immediate pitch up due trim and a/c gains circa 3,000 ft and then enters dynamic stall.
With the few precious facts that we have a this moment, why make stuff up that even contradicts those?
At the beginning of the climb:
- alternate law
- THS 3 deg up
- nose up input from PF

MountainSnake
30th May 2011, 20:25
If the airspeed data was erroneous/unavailable for 50 seconds or so and then became available why the aural "STALL" warning was not continuous since? I think an audible "STALL" and "SINK RATE" would be more than enough to get the crew aware. The question is: why there were no such alarms? Or why it sounded only when the sidestick was pushed forward, supposedly breaking away from the stall, or at least relieving it? Maybe I'm missing something...

ap08
30th May 2011, 20:33
According to common logic and some data on the net, the answer must be "YES". So yes, the TCAS must have failed due to bad (inconsistent?) altitude data, but whether the data was really wrong or the source of the data just stopped functioning, is impossible to tell.

When searching the net for this topic, I came to this youtube link called "Part of the series of 32 training videos of the A320. [17] IR 1 Fault IR Dis" This video is not for the faint of heart. Captain and co-pilot are going through FIVE MINUTES of checklists related to the failure of the system providing flight data... Maybe this checklist is doable in the safety of the simulator & VFR conditions when one can see the horizon... But I don't believe such a checklist can be completed over the ocean at night, with thunderstorms around, the plane out of control, multiple other alarms and the captain not in the cockpit!!!

toY7-WGrWhk

Shaka Zulu
30th May 2011, 20:53
@ Aeromech, post corrected because of course you are right and I should not have used no ''Air Date Input'', just no input from the Pitot probes

Rob Bamber
30th May 2011, 21:43
@ST27The aircraft pitched up steeply and decelerated from cruise speed to a virtual standstill in the first 30 seconds or so
There is no way an a/c at 38000 ft is going to decelerate fron Mach 0.82 to a virtual standstill in 30s. Imagine the forces on the flightcrew: why would they proceed? If they try, it'll stall well before the standstill.

The BEA report simply doesn't contain much information. Don't read too much into it.

Ask21
30th May 2011, 21:51
I just wonder if there exist such a thing as a "stall checklist" or even a "general catastrophic -check-list" that is designed to reveal - to the perhaps bewildered crew the true state of the flight.

I'm talking about a checklist that designed to be used in the situation where the captain returned to the cockpit in this flight. The situation that he may not have realized the true state of the flight.

Take a lesson from emergency medicine (where I have some expreience) . Whenever a traumatized patients is hospitalized something called Triage is performed. To help the doctors cope with the situation a simple A-B -C -D -rule is performed. This procedure is trained regularly - so it will pop up in the minds of all involved and also direct the treatment of the patient. So here goes:
A -- Airways - - Are the airways open and and not threatened (as by unconciousness or blod - swelling /injury etc) --> if yes continue --> if No - Intubate - open airways - cricotomy --once fixed-- go to B
B: Breathing : Is patient breathing good - if yes go to C -- If no -- clear the situation --> tension pneumothorax? Collapsed lungs ? -Chest Xray- Apply chest tube
C: Circulation --> Stable blood pressure? - Signs of major bleeding?Substitute fluids/blood. Stop any major bleeding --> emergency surgery to control bleeding.
D: Disability - Severe injury? - fractures? wounds? Neurological damage? CT-scans - X-rays - surgery to treat fractures etc
E: Minor injury - can wait to diagnose and treat

This rule was invented when one realized that patients died in CT-scan- machines etc because of bleeding - instead of being brought directly to surgery when indicated

So what would be the analogue within aviation? Please notice that in this checklist A-B-C is concerned with stabilizing the patient - so he will not die within minutes. D: is only performed when A-B-and C (stability -at least temporal ) is achieved. Pleas also notice that this procedure is done with with the full attention of all involved. If the patient is stable (not severely injured)- A-B-C will not take long time to establish - it its a critically ill patient surgery for A-B-C may take lot of efforts- lot of surgery - lot of time.

May I suggest : A- for Angle of Attack?

Meccano
30th May 2011, 21:52
Many moons ago I had a LHS pitot heat failue in an F50.
We were near top of descent when it happened, it was daylight, and I was aware of the consequences if we flew into icing.
We were in clear air, but I gave control to the F/O.

On descent we encountered a thin layer of cloud. We had no alternative - it was a continuous deck.
Within seconds of entering the layer (we went IMC) my airspeed suddenly rocketed upward toward VMO. It oscillated there for a few seconds then rapidly returned to an about normal reading.
Although I expected it, although I knew what was happening, although I had a good ADI in front of me - still - every fibre of my piloting instinct was screaming at me to pitch up to prevent the overspeed I was witnessing.

Of course, I didn't.
But - I was in daylight (even if IMC) and in relatively smooth air.
My excellent F/O was flying, and had normal ASI indications from a good pitot. Nothing had happened in terms of pitch/power changes to justify this abnormal lurch in speed, so my experience over-ruled my basic piloting instinct to react.

And we were in VMC in a minute, with normal ASI readings restored on my side.

But believe me - until you have experienced this - you will never understand the shock and disorientation it can cause.
At night, at high altitude, in heavy turbulence, with complex failures cascading through the systems and shutting down flight control functions - God help any pilot faced with this scenario. Do all the rationalising and armchair deconstructions you wish, but being in the hot seat at that fateful moment is an entirely different matter.

JJFFC
30th May 2011, 21:58
Jollin said
Quote:
Doesn't it seem intuitive that if a 200t jet transport has an IAS of < 60kts (and WOW says the plane is in the air), then it MUST be stalled, regardless of the AOA reading?
"No, it is just as likely (or more so) to be an instrumentation error. "

This sentence is frightening : a pilot that doesn't believe his instruments because he doesn't believe he could have made a mistake is a fool, nearly dead.

Alway believe your instruments. An instrument IS more reliable than any pilot.

The A300 lost speed for less than one minute: all others instruments were available.

IcePack
30th May 2011, 21:59
Touch'n'oops you are reading the little bus control laws. Big bus does have alt 1 & alt 2 & does not necessarily drop into direct law with gear down.
:=

Meccano
30th May 2011, 22:04
Alway believe your instruments. An instrument IS more reliable than any pilot.JJFC - I refer you to my post (previous to yours) and point out that it proves your statment is WRONG.

I'll say no more than that.

fullforward
30th May 2011, 22:54
Thousands of technicalities trying to explain the unexplicable:

- why BEA (and Air France, Airbus and ultimately the French Government) are hiding the whole CVR/FDR transcript? Why only this thin and very filtered information? What they are so affraid off? This is probably the most intriguing air disaster of the latest 50 years!

- why the pilots were unable to recognize a fully stalled aircraft and apply immediately corrective measures (valid for either a Cessna 152 or a B777, A330, ATR, you name it)? Only two explanations: a total lack of adequate training and basic airmanship or an A330 big design flaw that turns almost impossible to recover from a stall like this.

And then we'll be dealing with criminal negligence worth some billions of dollars.
THEY already know the truth and are scared about the consequences.:confused:

JJFFC
30th May 2011, 22:57
@meccano

I said an instrument is MORE reliable than a pilot.

It is a very very confusing question :

Let's say :

- the instrument is 99.99% reliable.
- the pilot is 97% reliable

You have 0.01% chance that the instrument is wrong vs 3% the pilot is wrong.

All is a question of chance. Some pilots are more lucky than the others. It belongs to the pilot to cope with the 3% or the 0.01%.

I'm glad for you.

Sincerely your's.

bubbers44
30th May 2011, 23:10
One day in a Lear Jet descending out of FL410 I leaned over to balance the fuel with the FO hand flying, that was in the days you could fly by hand, and when I looked forward I notice our airspeed was approaching red line, my attitude indicator showed a right 30 degree bank and increasing and we were turning right. I cross checked the other two attitude indicators and they agreed so told my FO I have it and leveled the wiings in the clouds and it took every bit of concentration to not follow my instinct to go back to what felt level. I was actually leaning sideways to feel right but still trusted the instruments. In this case however the IAS was wrong and needed to be disregarded. Recent Airbus Pitot static problems with other flights would not let me trust the airspeed instruments in this case. I can't believe anybody would certify an airliner that is stalled but the stall warning mutes because the pitot static system senses less than 60 knots. That is nuts.

ST27
30th May 2011, 23:28
ST27 Quote:
The aircraft pitched up steeply and decelerated from cruise speed to a virtual standstill in the first 30 seconds or so
There is no way an a/c at 38000 ft is going to decelerate fron Mach 0.82 to a virtual standstill in 30s. Imagine the forces on the flightcrew: why would they proceed? If they try, it'll stall well before the standstill.

The BEA report simply doesn't contain much information. Don't read too much into it. I was exaggerating somewhat, since the previous poster had suggested a constant deceleration throughout the incident, and that the ride might have seemed like horizontal flight.

The BEA report states that the IAS near the top of the ballistic path was 185 kts (about mach .59), and suggested that this was an accurate speed, since the indications on two instruments coincided.

Some simple physics calculations can be made to confirm that, given that when the aircraft started the episode, it was flying in level flight and at constant speed. As a rough assumption, it can be assumed that the energy needed to climb 3,000 feet will all come by bleeding off the energy of the forward motion of the aircraft.

The calculation suggests that they would have lost about 260 kts as a result of the climb, ignoring the effect of the TOGA power that was applied for a while during the climb. That puts us pretty close to the 185 kts that was recorded. So overall, they would have dropped from mach .82 to about mach .59 in about 30 seconds.

Perceived vertical acceleration would have been something like +1.5g near the start of the climb, and +0.5 g over the top. That certainly would have been noticed by both passengers and crew.

Meccano
31st May 2011, 00:23
JJFC
If you KNOW an instrument is faulty - are you seriously suggesting we follow it? I hope I'm misunderstanding you here, because any pilot is potentially 100% more reliable than a faulty instrument!
And unfortunately it's not always clear cut. Contradictory indications often occur.
Which instrument to believe then??

Then it is down to the skill and experience of the human at the controls, and he may have to utterly disregard the instrument right in front of him which is screaming for his attention. No easy feat, at the best of times.

bubbers44
31st May 2011, 00:26
Trapped frozen pitot tube pressure would give an overspeed zooming to 380 so probably explains the idle power. Once stalled descending at 11,000 ft per minute the ias would rapidly decrease as the static pressure increased. So at 60 knots ias the stall warning quits so the FO's think they have recovered from the stall are in a deep stall. What a system design. It took a lot of their final minutes comforted by false information. Hopefully the BEA will tell us more of what we know they have learned but their brief preliminary report leaving out so much data they have puzzled me. Maybe they have to run it by the French attorneys first.

pattern_is_full
31st May 2011, 01:22
Let's try and take this a piece at a time:

Beginning of the incident (first 11 seconds) -

"From 2 h 10 min 05, the autopilot then auto-thrust disengaged and the PF said "I have the controls". The airplane began to roll to the right and the PF made a left nose-up input. The stall warning sounded twice in a row. The recorded parameters show a sharp fall from about 275 kt to 60 kt in the speed displayed on the left primary flight display (PFD), then a few moments later in the speed displayed on the integrated standby instrument system (ISIS)."

- I would expect pitot icing to be a gradual process. Why is there a "sharp fall" of 215 kts in IAS at this point?

I don't doubt the probes were iced, I'm just wondering how that alone would drop the indicated speed so rapidly. If the pitots are blocked, this is not a "real" speed change, correct?

If the pitots are blocked and trapping pressure, a climb should result in an increase in indicated speed as static pressure drops. Correct? (That is not apparently what happened).

If the pitots are blocked, a descent would result in a drop in indicated speed as static pressure increases. Correct?

Graybeard
31st May 2011, 01:56
TCAS computation needs altitude to assess threats and should receive barometric and Radio Altimeter inputs! yes/ no?

TCAS depends on Range, Rate of Closure and Altitude Difference for Collision Avoidance, nothing more.

Range and Rate of Closure are determined by interrogating other aircraft's transponder. TCAS is like ground based ATC radar in that respect. Altitude Difference is found by subtracting other aircraft's reported altitude from own aircraft altitude.

TCAS receives Own Aircraft Altitude from the active ATC transponder, which in turn receives it from its associated Air Data Computer (ADR). This assures that the TCAS is calculating altitude difference from the same altitude that is transmitted to other aircraft TCAS.

Imperfect placement of the static ports on the side of the plane result in skewed static pressure at low airspeeds. The ADR corrects the static pressure based on airspeed when converting it to altitude for relay to the rest of the systems that use altitude.

The OZ A330 that had pitot icing in Aug 2009, indicated a sudden drop of 300 feet in measured altitude along with the airspeed decay to a low number, which is explained by the airspeed correction routine.

Why was the TCAS Fail reported on 447? BEA in their first release explained it was due to logic internal to the TCAS that would not accept the sudden drop in calculated altitude it was receiving.

Do you see the fallacy in that? If you don't want your TCAS working with bogus altitude, you sure don't want your ATC transponder working with it either. If there was such an altitude reasonableness check, it should be in the transponder, not the TCAS.

Maybe the TCAS Fail was like the Wiring Fail reported: the plane could have been getting the crap shaken out of it.

Cancel that last sentence. Found this from 16 April:

PJ2 said WRG means the fault is not correlated by another computer of the FWS.

I don't know why the TCAS reported Fail, but I'm certain it was not due to pitot error.

philipat
31st May 2011, 02:15
Using the standard practice of pitch + power to maintain safe flight does not work if the aircraft is ALREADY stalled, which was the case here.

But as I speculated in an earlier post, from the AVAILABLE data, it seems that that is precisely what they did. Would you agree?

bearfoil
31st May 2011, 02:23
Graybeard

"Maybe the TCAS Fail was like the Wiring Fail reported: the plane could have been getting the crap shaken out of it."

The autopilot dropped due to A) unreliable airspeed, B) exceeded control limits.

The a/p needn't be commanded to drop by the FMS (AD disagree). It will drop involuntarily all by itself if it cannot control the airplane, (within its limits). If it drops for this reason, Normal Law is retained with Stall protections and overbank protections. If for whatever reason the pitots inhale 30 knot disacrepant airflow, there we have AD disagree, though not ice caused, but turbulence caused. Now it drops to Alternate Law, but ostensibly for other than Unreliable Airspeed. If turbulence induced, one could argue it is not truly unreliable, but for 30 seconds some form of local upset in airflow has discreped the pitot tubes (perhaps both on the same side).

Any turbulence of this description can be sudden in onset. An updraft of 100 knots could be proposed, (Let's give it a radial component just to be mean). An argument could ensue whether its borders would be crisp enough to differentiate long enough between fuselage halves to cause UAS. Either way, there is an in and out (out and back in?) Law exchange that may have occurred. Musical protections? goddamitey, what a handful. (The radial component, from the left, would give it a left wing high result).

An updraft would give it a boost in lift, and a diminution of IAS. Enough of a drop in IAS to cause "UAS"?

IF AoA is AS and Vane reliant, a temporary boost in indicated AoA, reduction of IAS, and rising VS, does this fool the FCS? Was 447 in a transient and turbulence induced Phantom Upset? Something a hand flying pilot may have patiently sat through?

Autoflight into severe Turbulence? VIABLE?

Modern Elmo
31st May 2011, 02:58
... If the pitots are blocked, this is not a "real" speed change, correct?

Sorry, not correct. Pitot tube data is reality in regard to relative wind velocity flowing past the lifting surfaces. The pitot tubes provide the only indicated air speed data the flight instrumentation software and the pilots had, aside from seat of the pants feel and intuition.

If the pitots are blocked and trapping pressure, a climb should result in an increase in indicated speed as static pressure drops. Correct? (That is not apparently what happened).

Ice blocking or clogging pitot tubes is not likely to "trap" dynamic pressure, which is (1/2)*air density*(relative wind velocity)^2. Instead, ice clogging the tube will tend to shelter the pressure transducer from dynamic pressure. Less dynamic pressure = slower indicated airspeed.

Pitot-Static (Prandtl) Tube (http://www.grc.nasa.gov/WWW/K-12/airplane/pitot.html)

So NO, a climb will not result in a increase in IAS in the pitot tube scenario you describe.

...

The transcript which has been released is probably incomplete, as a couple of commenters here have already pointed out. I'll bet those three pilots did a lot more talking on their way down.

bearfoil
31st May 2011, 03:06
Modern Elmo

"... If the pitots are blocked, this is not a "real" speed change, correct?

"Sorry, not correct. Pitot tube data is reality in regard to relative wind velocity flowing past the lifting surfaces. The pitot tubes provide the only indicated air speed data the flight instrumentation software and the pilots had, aside from seat of the pants feel and intuition. "

Excuse me?

matthewsjl
31st May 2011, 03:13
Using the standard practice of pitch + power to maintain safe flight does not work if the aircraft is ALREADY stalled, which was the case here

Actually, I think they did have a chance to use pitch/power. The BEA report states that the aircraft was stalled for the last 3m30s of the flight. The autopilot/throttle kicked out ~4m30 seconds before the recording stopped and that minute between the auto-pilot/throttle leaving and the actual stall appears to be a pilot induced climb with no change in power settings = pilot induced stall.

Of course, once in the stall recovery is a different matter.

Modern Elmo
31st May 2011, 03:17
"... If the pitots are blocked, this is not a "real" speed change, correct?

Pitot tubes clogged with ice sure can result in a real change in indicated airspeed.

Mimpe
31st May 2011, 03:41
I posted elsewhere, but as you indicate, there will turn out to be a significant degree of unrecognised spatial disorientation in the accident, probably somatogravic with false sensation of pitch down leading to nose up command and stall.

Insufficent trust of remaining instrument indications , and the complexity and foibles of an overly complex avionic system that performs poorly at the edge of the envelope......

pattern_is_full
31st May 2011, 04:57
Modern Elmo, by "real" speed change I meant the actual speed of the plane, not what was indicated.

I.E. - did the aircraft actually "sharply" lose 215 kts of TAS (or whatever 215 kts IAS equates to at that altitude, in TAS), or was that indicated "sharp" change an artifact of the icing of the pitot and/or other things - not including the "real" speed.

Sorry if I was unclear.

jcjeant
31st May 2011, 05:31
Hi,

A little "OT" but interesting ...

Flight AF 447
Analysis of Air France’s crisis communications

By Hédi Hichri
Account Director
Fleishman-Hillard France, September 2009

http://www.multiupload.com/0G4RRWNBYS

MountainBear
31st May 2011, 05:51
I posted elsewhere, but as you indicate, there will turn out to be a significant degree of unrecognised spatial disorientation in the accident, probably somatogravic with false sensation of pitch down leading to nose up command and stall.

What garbage.

I suspect that whatever BEA comes up with will be controversial. We can record what the plane does on the DFDR. We can record what the flight crew says on the CVR. But what we cannot record is WHY they did what they did, unless they say so explicitly, which rarely happens. There is no mind reading device; it doesn't exist. Correlation doesn't equal causation.

Because we cannot read their minds and know their motivations, we are left with being able to only judge the process and the result. The result we already know, and we labor under the burden of hindsight bias. So that just leaves the process. Did they follow their training? Were their actions up to professional standards? If the answer is yes, then the cause of the accident lies elsewhere.

jcjeant
31st May 2011, 06:32
Hi,

AF447… What We Now Know « Dark Matter (http://msquair.wordpress.com/2011/05/27/af447-what-we-now-know)
The Right Attitude « Dark Matter (http://msquair.wordpress.com/2011/05/27/the-right-attitude)

Lemain
31st May 2011, 07:47
- why BEA (and Air France, Airbus and ultimately the French Government) are hiding the whole CVR/FDR transcript? Why only this thin and very filtered information? What they are so affraid off? This is probably the most intriguing air disaster of the latest 50 years!French was the language being used. Anything in English must have been translated. Translating anything is risky and aviation talk is full of jargon, acronyms, and technical comments....in this case, very probably seasoned with fear. They probably haven't had the CVR for long enough to prepare a certified translation.

CONF iture
31st May 2011, 08:57
FDR data do well in French too and original CVR is just perfect ...

HalloweenJack
31st May 2011, 09:08
they`ve had the data from both for what? 30 days? and you all want it in the public domain? how about actually investigate first before pampering to the whims of forum hero`s.

we wont see the information for a while yet - this time nexr year most likely.

shogan1977
31st May 2011, 10:04
This Der Spiegel article was posted earlier by someone else, but resulted in zero discussion: Doomed Flight AF 447: Questions Raised about Airbus Automated Control System - SPIEGEL ONLINE - News - International (http://www.spiegel.de/international/world/0,1518,765764,00.html)

Several of the points raised in this article have not even been touched upon by this group - in particular the potentially detrimental role of the horizontal stabilizer and the questioned culpability (beyond human error) of EASA, Thales (pitot tubes) and potentially Airbus...

But why would co-pilot Bonin pull up instead of pushing the nose down? It wasn't long before the plane's angle became dangerously high.

An explanation for the A330's rising nose, however, could also be provided by a line in the BEA report referring to the trimmable horizontal stabilizer. Situated at the tail of the aircraft next to the flaps controlling the aircraft's pitch, known as the elevator, the horizontal stabilizer likewise helps control the plane's horizontal stability.
According to the BEA's interim report, the horizontal stabilizer moved from three degrees to 13 degrees, almost the maximum. In doing so, it forced the plane into an increasingly steep climb. It "remained in the latter position until the end of the flight," the report notes.

Gerhard Hüttig, a professor at the Institute of Aeronautics and Astronatics at the Technical University in Berlin, considers the high angle of the horizontal stabilizer to be a failure of the Airbus' electronic flight control system. Hüttig, a former Airbus pilot himself, calls it "a programming error with fatal consequences."

"No matter how hard the crew tried to push down the nose of the aircraft, they would have had no chance," Hüttig says.

Exactly what orders [Captain Marc Dubois] issued [after re-entering the cockpit] are not part of last Friday's report. But sources close to the investigation are saying that he said: "This is a stall. Reduce power and nose down!"

This order would have been the correct one were the situation not already hopeless. By that time, the jet, which was pointing steeply upwards, was already losing vertical altitude at a rate of 200 kilometers per hour.

Indeed, the BEA report documents efforts undertaken following the captain's return to bring the plane's nose down. Forty-one seconds before impact, both co-pilots were pushing on the controls. Then Bonin cried desperately: "Go ahead, you have the controls." There were just 30 seconds left before the end.

But why were all the crew's efforts in the cockpit in vain? Did the plane no longer react to the cockpit commands as it fell? Or did the horizontal stabilizer, which was still almost fully deflected at 13 degrees, continue to force the nose of the plane up?

Hüttig, who also advises the victims' families regarding technical issues, is concerned about the description of the horizontal stabilizer as being at 13 degrees. That is consistent with behavior he observed in an Air France A330 simulator in Paris a few months ago, when he replicated the situation together with other pilots. "The phenomenon is startlingly similar," he says.

Was it really the stabilizer that doomed the pilots? In theory, they could still have adjusted it -- its position can be manually altered using a wheel near the thrust levers. But as Hüttig notes, one would first have to know that the stabilizer is deflected.

Huttig pointed out that Airbus published a detailed explanation of the correct behavior in the event of a stall in the January issue of its internal safety magazine. "And there, all of a sudden, they mention manually trimming the stabilizers," he says.

It remains an open question who will be proved right at the end of the investigations. But it is already clear that no one individual will bear the burden of responsibility alone. The pilots could have stabilized the aircraft if they had reacted differently. But the airline had also probably not prepared them properly for such a situation. Similarly, Airbus' recommendations were insufficient. That much is spelled out in the files of the French authorities which investigated the crash of the A330. "To date," the experts say, the deficiencies have "not been rectified."


The Pitot Tubes and culpability of EASA?
As stated in the report (2h 10min 05sec) the autopilot and auto-thrust disengaged due to icing of the pitot tubes (manufactured by Thales - see below) which resulted in loss of speed readings.

If the speed sensors fail, it has a "particularly confusing" effect in Airbus models, the experts say, pointing to the high degree of automation in the cockpit. "If the control computers, which are actually supposed to provide more safety, fail, then the automatic systems can become a danger at that moment," says William Voss, president of the Flight Safety Foundation.

The manufacturer Thales was well aware of the catastrophic consequences of a failure of the speed sensors as early as 2005. At the time, the French company concluded that such a failure could "cause plane crashes."

A total of 32 cases are known in which A330 crews got into difficulties because the speed sensors failed. In all the cases, the planes had pitot sensors from Thales, which were significantly more prone to failure than a rival model from an American manufacturer.

But none of the responsible parties intervened. In 2007, Airbus merely "recommended" that the sensors be replaced. Air France took that as a reason not to carry out the costly work -- and it even got official blessing for doing so. The European Aviation Safety Agency wrote that it currently saw "no unsafe condition that warrants a mandatory modification of the Thales pitot tubes."

Several comments have been made here claiming that the passengers wouldn't have noticed anything...(I wish it were true)The passengers, who had just a short time before been pressed into the backs of their seats, were now being held into their seats only by their seatbelts. "At this moment, I would have feared for my life even if I was sitting in the passenger cabin," said one A330 pilot after reading the BEA report. That the plane was in freefall would have been clear to all on board. The nose of the plane pointed skyward at an angle of 16 degrees. "That's more than immediately following takeoff," the pilot said.

YorkshireTyke
31st May 2011, 10:25
...........I'll bet those three pilots did a lot more talking on their way down.

I bet there were a few " merde's" being thrown around !

shogan1977

Nice, I agree. I know nothing about the Airbus, is there any indicator readily available to the pilots to show what angle the stabiliser is at ? Is there any way of trimming the stabiliser really "manually" ?

lomapaseo
31st May 2011, 10:30
Shogan1977

I prefer to see facts rather than claims in a self serving article (lawyereese speak)

The above is nicely laid out to assess blame before the report is finished.

Such words as culpability have no meaning without examining all facts

Also I really don't understand how one can assign a regulatory word of "catastrophic" to a single system manufactuer such as "Thales". The presumption should have been a simple failure condition (if operated outside its certified enevelop) to be accomodated by the installer (Airbus)

ExSp33db1rd
31st May 2011, 10:39
..........Is there any way of trimming the stabiliser really "manually" ?

Good point, the old 707 had two dirty great 'coffee grinder' wheels on the sides of the central consol, so that the pilots could really 'manually' trim the stabiliser should it decide to do something one didn't want. Sometimes one had to relieve the airload on the stabiliser by pushing the nose in the opposite direction to that desired, then when the pressure was reduced cranking the handle like mad in the desired direction. In this context the pilots may have had to pull the nose up even further momentarily of course to operate this truly manual method.

There was also a pointer which moved along a scale, so that one could see what angle the stabiliser was at.

Course it's all computerised now, therefore far superior, so nothing can go wrong, go wrong, go wrong.

jcjeant
31st May 2011, 10:43
Hi,

Nice, I agree. I know nothing about the Airbus, is there any indicator readily available to the pilots to show what angle the stabiliser is at ? Is there any way of trimming the stabiliser really "manually" ?

Good point, the old 707 had two dirty great 'coffee grinder' wheels on the sides of the central consol, so that the pilots could really 'manually' trim the stabiliser should it decide to do something one didn't want.
Same for Airbus

Answer was already posted somewhere in this forum (with pics)
The answers are YES for the two questions.

edga23
31st May 2011, 10:45
To ExSp33db1rd

Same system on A320.
Of course normally the AUTO-TRIM does it automatically, but you can do it manually with the wheel IF NEEDED.
The angle is also indicated

DouglasFlyer
31st May 2011, 10:47
There are two PITCH TRIM wheels on the mid pedestal. They have scales to set the CG for take-off. Inflight the CG scale is not valid but the indicator shows the position of the THS (trimmable horizontal stabilizer).
The THS is only controllable manually when on ground or when inflight in direct law. In direct law one uses the wheel to trim the pitch manually - therefore USE MAN PITCH TRIM is displayed on the PFD.

Oooops: two've been faster...

fireflybob
31st May 2011, 10:47
So if the THS is 13 deg up and the sidestick held fully forward, will the a/c recover from the stall?

jcjeant
31st May 2011, 10:52
Hi,

So if the THS is 13 deg up and the sidestick held fully forward, will the a/c recover from the stall? Add to your question the AOA angle .. the air speed and the altitude of the AC ... as it can be important to know the outcome ......

shogan1977
31st May 2011, 10:52
DouglasFlyer: "The THS is only controllable manually when on ground or when inflight in direct law. In direct law one uses the wheel to trim the pitch manually - therefore USE MAN PITCH TRIM is displayed on the PFD."

Does this mean they would NOT have been able to trim the pitch in Alternate Law?

fireflybob
31st May 2011, 10:56
Add to your question the AOA angle .. the air speed and the altitude of the AC ... as it can be relevant ......

Assume sufficient height for recovery - the question I am asking is that with the THS at 13 deg up and the side stick held fully forward and the engines at idle thrust (which they were) is the stall recoverable? What difference would positioning the THS fully forward make?

jcjeant
31st May 2011, 10:56
Hi,

Quote:
DouglasFlyer: "The THS is only controllable manually when on ground or when inflight in direct law. In direct law one uses the wheel to trim the pitch manually - therefore USE MAN PITCH TRIM is displayed on the PFD."
Does this mean they would NOT have been able to trim the pitch in Alternate Law?


This mean that they were able to use manually the trim wheels
The manual trim is available under all laws

jcjeant
31st May 2011, 10:59
Hi,

What difference would positioning the THS fully forward make? Undoubtly a big difference but keep in mind the AOA and air speed factors.....

shogan1977
31st May 2011, 11:04
jcjeant: "The manual trim is available under all laws"

DouglasFlyer: "...only in direct law..."

Who should I believe? :confused:

jcjeant
31st May 2011, 11:26
Hi,

In its conclusions the BEA makes no allusion to the pitot tubes to justify the inconsistent speeds

What would happen if a high speed upwind (possible bad weather in area) of + - 100 Km / h met the static probes ...
That will he not cause a significant decrease in the indicated airspeed .. and this does he not bring up the plane very quickly?

aeromech3
31st May 2011, 11:26
As with ExSp33dblrd reply for a B707, manual cranking of a TP trim wheel can be arduously slow, on some craft there is an electric trim motor (B727 example) which does this work much quicker, how about on the A330?

jcjeant
31st May 2011, 11:28
Hi,

Who should I believe?
which does this work much quicker, how about on the A330? Check this !
http://www.smartcockpit.com/data/pdfs/plane/airbus/A330/systems/A330-Flight_Controls.pdf

Also:
http://img402.imageshack.us/img402/8669/thsinfo.jpg

Zorin_75
31st May 2011, 11:34
This Der Spiegel article was posted earlier by someone else, but resulted in zero discussion:
It adds nothing to the discussion but some highly tendentious speculations...


According to the BEA's interim report, the horizontal stabilizer moved from three degrees to 13 degrees, almost the maximum. In doing so, it forced the plane into an increasingly steep climb.As far as we can gather from the report, at least initially not the THS forced the plane nose up, but the stick input did.

2h10m51:
Stall warning
(...)
PF maintained nose-up inputs
(...)
The trimmable horizontal stabilizer (THS) passed from 3 to 13 degrees nose-up in about 1 minute
(...)
The PF continued to make nose-up inputs
(...)

2 h 11 min 40:
The PF made an input on the sidestick to the left and nose-up stops, which lasted about 30 seconds

2 h 12 min 02:
Around fifteen seconds later, the PF made pitch-down inputs. In the following moments, the angle of attack decreased

This is the first mention of any nose down input after the stall warning, 1m26 later. It is not known how long this input lasted (and BTW it is also not known whether PF ceased the ND input due to the reactivated stall warning, as many here claim).


Forty-one seconds before impact, both co-pilots were pushing on the controls.We don't know that. The report states merely:
simultaneous inputs by both pilots on the sidesticks were recorded


Then Bonin cried desperately: "Go ahead, you have the controls."Report says: and the PF said "go ahead you have the controls".
Admittedly probably not dramatic enough for a "serious" publication.


The passengers, who had just a short time before been pressed into the backs of their seats, were now being held into their seats only by their seatbelts.Which would necessitate a continuous downward acceleration. We know downward velocity at 2h11m40 to be -10000 fpm, final velocity at 2h14m28 to be -10912 fpm. :(
They appear to have reached terminal velocity pretty early on.

LandIT
31st May 2011, 11:40
Quote...

The passengers, who had just a short time before been pressed into the backs of their seats, were now being held into their seats only by their seatbelts. "At this moment, I would have feared for my life even if I was sitting in the passenger cabin," said one A330 pilot after reading the BEA report. That the plane was in freefall would have been clear to all on board. The nose of the plane pointed skyward at an angle of 16 degrees. "That's more than immediately following takeoff," the pilot said.

Unquote.

Having flown many times and thinking about my built-in senses of horizontal and gravitational, I tend to agree. To me the unanswered question is then - why didn't the pilots realise they were pointed up towards the sky and they were falling like a leaf? They could see the altitude bleading away extremely rapidly. Could they not read the attitude also? At least they knew they were pulling up!

REALLY, did they think they were diving! Continuous efforts to pull up over more than 2mins had resulted in no reduction in loss of altitude, so why didn't they realise they were "going down backwards" - well, almost. It seems ridiculous in hindsight that pulling up over that length of time and not reducing the descent MUST only mean you are not diving, you are stalled. Easy to say now, but those guys are supposed to be professionals, yes?

A major contributing factor must be the 13 deg THS trim. I know, if you pull up continuously you will get the THS auto trim as well but for the autotrim to then later give up and LEAVE the aircraft in this trim, ESPECIALLY if pilots are trained NOT to touch the trim, is "less than desirable" IMO (mildly). Surely a recommendation needs to come from this unfortunate part of the control setting, either re-trim back to neutral when giving up or make the pilots check the trim wheel = SOP/training. Not the first time (Perpignan), lets make it the last.

jcjeant
31st May 2011, 11:41
Hi,

2 h 12 min 02:
Around fifteen seconds later, the PF made pitch-down inputs. In the following moments, the angle of attack decreasedAnd we don't know if the vertical stabilizer angle changed during those pitch down inputs ...
We only know it changed when it was pitch up inputs.

shogan1977
31st May 2011, 11:42
Thanks Zorin75 - Your clarification is well taken and duly noted.

DouglasFlyer
31st May 2011, 11:43
jcjeant is right!
Sorry for the wrong expression: should have read "only controlled" instead of "only controllable".
Manually moving the pitch trim wheel overrides the auto trim.

Patty747400
31st May 2011, 11:50
Quote from Air France:

"The crew, made up of three skilled pilots, demonstrated a totally professional attitude and were committed to carrying out their task to the very end and Air France wishes to pay tribute to them."

I'm not ready to put all the blame on the pilots. However, a statement like this at this time makes me think they have hired "Bagdad Bob" as their press officer. Is this just French arrogance or do they know something we don't?

Elledan
31st May 2011, 11:57
On a Dutch news site here ( Inmiddels 77 lichamen uit (http://www.nrc.nl/nieuws/2011/05/31/inmiddels-77-lichamen-uit-af447-geborgen/) ) the following claim is made (translated into English):
The pilots wanted, thus becomes clear from the 'current conclusions' from the investigation into the two black boxes of the plane, to fly over a lightning storm, but were prevented from this because it wasn't possible due to the temperature to fly to that height.Reading this kind of surprised me, as I didn't have the impression that they wanted to fly over the storm, but it would explain why they suddenly went into this steep climb.

000tfm000
31st May 2011, 12:01
Apologies: I posted essentially the same message as this a bit later (below) - not having noticed that there would be a delay pending moderation.

Zorin_75
31st May 2011, 12:08
"The crew, made up of three skilled pilots, demonstrated a totally professional attitude and were committed to carrying out their task to the very end and Air France wishes to pay tribute to them."

I'm not ready to put all the blame on the pilots. However, a statement like this at this time makes me think they have hired "Bagdad Bob" as their press officer. Is this just French arrogance or do they know something we don't?
Whatever the investigation will reveal, there can't be any doubt whatsoever that these men did everything they could to save the plane. Now the task should be to find out why that wasn't enough. Not to put blame but to learn.

jcjeant
31st May 2011, 12:10
Hi,

I'm not ready to put all the blame on the pilots. However, a statement like this at this time makes me think they have hired "Bagdad Bob" as their press officer. Is this just French arrogance or do they know something we don't?

When I read the Air France statement .. I ask myself (already posted)
Why Air France will make such statement ? .. as maybe the final report will go in a contrary way .....
Maybe they know more on the CVR-FDR that what we know ?

AAIGUY
31st May 2011, 12:12
had they done NOTHING or atleast followed the Unreliable Airspeed Abnormal Checklist and turn to the GPS page for speed and Alt..

No they weren't hero's. If (and I say) the BEA report is correct they were idiots.
Like the A340 crew in YYZ

Patty747400
31st May 2011, 12:18
"there can't be any doubt whatsoever that these men did everything they could to save the plane."

So you mean sitting with the stick pulled fully back for 3,5 minutes while you are descending with 10000 fpm demonstrates a "totally professional attitude"?

What I'm saying is, if AF know more than we do, they might have a point. But, from what we know so far... absolutely not.

Just as I won't put all the blame on the pilots before I have the final report you should be careful to completely clear them of responsibility. Can we agree on that?

000tfm000
31st May 2011, 12:34
To me as a lawyer with an interest in aviation safety, the preliminary report implies that the design of the stall warning system may have been a major contributory factor in this accident.

The PF was confronted with conflicting signals as well as degraded instruments. Nevertheless, at quite an early stage, his inputs commanded nose-down pitch. He appears successfully to have initiated a recovery. What he needed to do, was to develop this response further.

However, the stall warning system did not recognise this. It did not encourage the PF to develop his solution further. On the contrary, it sounded a stall warning. This is essentially because it could not reward the improving trend which the PF had initiated: it could only recognise the threshold above which the stall warning should be available (<60knots = stall warning unavailable; >60knots = stall warning available).

A correct interpretation of the stall warning would possibly have been difficult in any situation. Particularly in the difficult conditions which must have prevailed at the time, the PF may well have inferred that there was a causal connection between the stall warning and his most recent command: ie, nose-down. Naturally, he would have wished to reverse the cause. So he would command nose-up instead.

What is worse, the PF would now have learned by experience that commanding nose-down pitch would "cause" a stall warning. He would have been reluctant to try it again.

Therefore, my tentative view is that the stall warning at this stage in the attempted recovery gave precisely the wrong message to the PF. It may well have been an important step in the "critical path" of the accident.

I think we should not rush to blame the pilots: the term "pilot error" sometimes disguises the degree to which "human error" has been induced by automatic systems.

CJ Driver
31st May 2011, 12:50
This thread is galloping forwards so fast that I'm replying to something three pages ago, but it was only a few hours ago, and it needs answered because it is another daft blind alley.

Someone said:
I can't believe anybody would certify an airliner that is stalled but the stall warning mutes because the pitot static system senses less than 60 knots. That is nuts.

I think you will find that is completely normal, and even a microsecond of thought will tell you why. Think "parked on the taxiway". There's a strong chance the wing is fully stalled, but we'll supress the stall warning until we've got some speed up, thank-you.

Zorin_75
31st May 2011, 12:58
So you mean sitting with the stick pulled fully back for 3,5 minutes while you are descending with 10000 fpm demonstrates a "totally professional attitude"?
First of all paying tribute to those men is not a matter of arrogance but of decency.
No, what I'm saying is at that point, to them pulling on that stick appeared to be the best way to save the plane.
Considering what we know now (which is, as has been said numerous times, still very little), that was likely not the case and probably the final report will prove us, sitting in our comfy chairs, right and those men who died that night wrong.
But what then? It's so easy to shrug it off, label them as idiots and go back to business, while learning from their mistakes will be work and will cost money. But I think we owe it to them.

jackx123
31st May 2011, 13:01
Patty: agree totally.

as another earlier post pointed out. At 350, flight controls neutral and correct trust setting should get you out at lower alt with faulty IAS. not rated on 330 but sure as hell works for most other tubes with wings that I flown in the past.

Capn Bloggs
31st May 2011, 13:14
Someone said:

Quote:
I can't believe anybody would certify an airliner that is stalled but the stall warning mutes because the pitot static system senses less than 60 knots. That is nuts.

I think you will find that is completely normal, and even a microsecond of thought will tell you why. Think "parked on the taxiway". There's a strong chance the wing is fully stalled, but we'll supress the stall warning until we've got some speed up, thank-you.
Ever heard of a squat switch?

ATC Watcher
31st May 2011, 13:16
Great Post Zorin_75.
You're absolutely right.

Zorin_75
31st May 2011, 13:16
the preliminary report implies that the design of the stall warning system may have been a major contributory factor in this accident.

The PF was confronted with conflicting signals as well as degraded instruments. Nevertheless, at quite an early stage, his inputs commanded nose-down pitch. He appears successfully to have initiated a recovery. What he needed to do, was to develop this response further.

However, the stall warning system did not recognise this. It did not encourage the PF to develop his solution further. On the contrary, it sounded a stall warning.
First mention of a nose down input is here:

2 h 10 min 16:
(...)The airplane’s pitch attitude increased progressively beyond 10 degrees and the plane started
to climb. The PF made nose-down control inputs and alternately left and right roll inputs. The
vertical speed, which had reached 7,000 ft/min, dropped to 700 ft/min and the roll varied
between 12 degrees right and 10 degrees left. The speed displayed on the left side increased
sharply to 215 kt (Mach 0.68) (...)

At 2 h 10 min 51, the stall warning was triggered again. The thrust levers were positioned
in the TO/GA detent and the PF maintained nose-up inputs.(...)
Around fifteen seconds later, the speed displayed on the ISIS increased sharply towards 185 kt;it was then consistent with the other recorded speed.


So IAS was well above 60 kt at this point. The stall warning simply meant they were going into a stall.
The only time a reappearing stall warning due to nose down / increasing IAS is mentioned is much later:

At 2 h 12 min 02, (...) Around fifteen seconds later, the PF made pitch-down inputs. In
the following moments, the angle of attack decreased, the speeds became valid again and the
stall warning sounded again.

But the report doesn't say anything at all about the PF's reaction to that warning.

JCviggen
31st May 2011, 13:22
What is worse, the PF would now have learned by experience that commanding nose-down pitch would "cause" a stall warning. He would have been reluctant to try it again.

That is probably true on a basic pshychological level...but shouldn't a pilot have a bit more of a grasp on the physics of flying? Why would lowering the nose in this case cause a stall warning? And even without the stall warning sub-60kts, the altimeter was still winding down in spectacular fashion with engines at full and the nose up for a good amount of time. I know about heat of the moment and all that but its amazing the amount of time that passed without the full stall becoming apparent to them.

cwatters
31st May 2011, 13:35
@ costamaia



@CWatters

Quote:
Why wasn't full power applied?

Wasn't it?
From the BEA 27 May report (http://www.bea.aero/fr/enquetes/vol.af.447/point.enquete.af447.27mai2011.en.pdf):
"At 2 h 10 min 51, the stall warning was triggered again. The thrust levers were positioned in the TO/GA detent and the PF maintained nose-up inputs."

"The altitude was then about 35,000 ft, the angle of attack exceeded 40 degrees and the vertical speed was about -10,000 ft/min. The airplane’s pitch attitude did not exceed 15 degrees and the engines’ N1’s were close to 100%."

I meant later when they still had a high rate of descent..


At 2 h 12 min 02, the PF said "I don’t have any more indications", and the PNF said "we have no valid indications". At that moment, the thrust levers were in the IDLE detent and the engines’ N1’s were at 55%. Around fifteen seconds later, the PF made pitch-down inputs. In the following moments, the angle of attack decreased, the speeds became valid again and the stall warning sounded again.

...although I admit it doesn't mention what they did with the throttles after that.

fboizard
31st May 2011, 13:40
I am French, so I have the happiness to read the BEA report in the text.

It is very confused and incomplete. Don't trust it too much and don't exhaust yourself trying to make a coherent theory from it.

For example, there is not enough informations to understand why the A330 climbed and stalled at 38 000 ft :

> the pilot gives «ordres à cabrer» (pitch-up orders)

> then the PF gives «ordres à piquer» (pitch-down orders)

and then «le PF mantient ses ordres à cabrer» (the PF keeps giving pitch-up ordres)

Obviously, there is something missing here : when did the PF resume his pitch-up orders after having tried the pitch-down orders ? And why ?

The whole report is like this : ill-phrased, hardly understandable and lacunar.

Be careful when you use this report : I thing some very important informations are missing (or withheld ?).

cwatters
31st May 2011, 13:47
Its probably been said before in the last 55 pages but,

If you lose sensible airspeed and altimeter indications, disregard all and fly attitude and zero bank angle for normal cruise flight with relevant manual throttle setting. Been there, done that.

Try it in the sim.

Does that work if you start in the stalled condition with high rate of descent and 40 degree AOA? Will it accelerate out of the stall at cruise throttle?

Graybeard
31st May 2011, 13:49
Shogan1977, from Der Spiegel:
Quote:
The manufacturer Thales was well aware of the catastrophic consequences of a failure of the speed sensors as early as 2005. At the time, the French company concluded that such a failure could "cause plane crashes."

A total of 32 cases are known in which A330 crews got into difficulties because the speed sensors failed. In all the cases, the planes had pitot sensors from Thales, which were significantly more prone to failure than a rival model from an American manufacturer.

But none of the responsible parties intervened. In 2007, Airbus merely "recommended" that the sensors be replaced. Air France took that as a reason not to carry out the costly work -- and it even got official blessing for doing so. The European Aviation Safety Agency wrote that it currently saw "no unsafe condition that warrants a mandatory modification of the Thales pitot tubes."


Money is in play here, I'm sure. Typically, if the component maker or airframe builder make a Service Bulletin mandatory, they pay for it. If the SB is optional, the airline pays. I've known airlines who refuse to pay for SB that are to correct defects, regardless.

ST27
31st May 2011, 14:02
Quote...

The passengers, who had just a short time before been pressed into the backs of their seats, were now being held into their seats only by their seatbelts. "At this moment, I would have feared for my life even if I was sitting in the passenger cabin," said one A330 pilot after reading the BEA report. That the plane was in freefall would have been clear to all on board. The nose of the plane pointed skyward at an angle of 16 degrees. "That's more than immediately following takeoff," the pilot said.

Unquote.

Having flown many times and thinking about my built-in senses of horizontal and gravitational, I tend to agree. The news report was utter rubbish, and included unnecessary sensationalism. And Miles O'Brien wondered why the media gets no respect from the pros.

The passengers were never pressed into the backs of their seats, since the aircraft was losing speed. They were never held only by their seatbelts, since that would require negative G's, which they never would have seen as a result of the maneuvers described in the BEA "note".

The initial pitch up would not have been much different than experienced when rotating for taking off. The ride over the top would have certainly been noticed, when they went from a high rate of climb to high rate of descent, but passenger's behinds would have always been solidly in their seats, not dangling from their seatbelts, as suggested in the article.

Once descending, the rate of descent didn't change, so passengers would have only sensed that the nose was pointed up, somewhat like an initial climbout on takeoff on say a DC-10 or 757. There also would have been heavy buffeting. Given that they were flying at night in a storm, the passengers would have had no outside references to know what was happening, and would not have known they were falling. A clue would have been the change in cabin pressure, but how many passengers would connect that with rapid descent?

To me the unanswered question is then - why didn't the pilots realise they were pointed up towards the sky and they were falling like a leaf?They weren't falling like a leaf, in the sense of fluttering to earth. As far as the why, that is for the accident report to answer. Like the Colgan Air pilot in Buffalo, they didn't take what should have been an almost reflexive action on hearing the stall warning, namely push the nose down.

They could see the altitude bleading away extremely rapidly. Could they not read the attitude also? At least they knew they were pulling up!The PF knew he was pulling up, but are you sure the PNF knew it? It's not quite as obvious what the other guy is doing with sidesticks, particularly if you are concentrating on a checklist.

It seems ridiculous in hindsight that pulling up over that length of time and not reducing the descent MUST only mean you are not diving, you are stalled. Easy to say now, but those guys are supposed to be professionals, yes?Yes, it's easy to say when you know what the end result was, and have had a long time to ponder the situation. Obviously, they were pros, and they were confused about what was happening. The question is why the PF decided to pull back the stick in the first place, since that would indicate what he initially thought was wrong, and set his frame of mind about what needed to be done. It often takes time for someone under great stress to notice things going on around them, since they tend to focus on specific problems with a form of mental tunnel vision. They can therefore miss clues that would be obvious to those not under stress.

ST27
31st May 2011, 14:24
Quote: Quote:
The manufacturer Thales was well aware of the catastrophic consequences of a failure of the speed sensors as early as 2005. At the time, the French company concluded that such a failure could "cause plane crashes."

A total of 32 cases are known in which A330 crews got into difficulties because the speed sensors failed. In all the cases, the planes had pitot sensors from Thales, which were significantly more prone to failure than a rival model from an American manufacturer.

But none of the responsible parties intervened. In 2007, Airbus merely "recommended" that the sensors be replaced. Air France took that as a reason not to carry out the costly work -- and it even got official blessing for doing so. The European Aviation Safety Agency wrote that it currently saw "no unsafe condition that warrants a mandatory modification of the Thales pitot tubes."
Money is in play here, I'm sure. Typically, if the component maker or airframe builder make a Service Bulletin mandatory, they pay for it. If the SB is optional, the airline pays. I've known airlines who refuse to pay for SB that are to correct defects, regardless.


More rubbish from Der Spiegel. Air France was in the process of changing out the pitot tubes. They received their first shipment of replacement parts a week before the accident, but had not applied them to that particular aircraft.

As to why they did nothing for two years, consider that they were told that there was no safety problem by both the manufacturer and the regulator, and they must have agreed, so why do anything? It's not as though pitot tubes are that expensive when compared to other costs. It was only after a few other incidents that they took action on their own to start the replacements.

stepwilk
31st May 2011, 14:24
On a Dutch news site here ( Inmiddels 77 lichamen uit ) the following claim is made (translated into English):
Quote:
The pilots wanted, thus becomes clear from the 'current conclusions' from the investigation into the two black boxes of the plane, to fly over a lightning storm, but were prevented from this because it wasn't possible due to the temperature to fly to that height.
Reading this kind of surprised me, as I didn't have the impression that they wanted to fly over the storm, but it would explain why they suddenly went into this steep climb.
31st May 2011 07:50

Elledan, the Dutch news site is wrong. To be sure of climbing over an ITCZ "lightning storm," the AF flight crew would have to have assumed they might well have to climb as high as 55,000 feet or so, and to do that, they'd have needed the Space Shuttle, not an Airbus. Their sudden climb to 380 had nothing to do with any attempt to top a thunderstorm.

bearfoil
31st May 2011, 14:32
ST27

"The PF knew he was pulling up, but are you sure the PNF knew it? It's not quite as obvious what the other guy is doing with sidesticks, particularly if you are concentrating on a checklist."

It took me three pages to catch up and catch this statement, the rest mostly rehash, argument, etc.

Inferred in this statement are some very basic questions as to where cockpit management and aviating clash. If it turns out that PF was handling the situation poorly (and we have no idea if that is the case), then we have single pilot crew. Not trashing that concept, but ST27 points to a fundamental flaw (perhaps?) in allowing (mandating) a review of procedures developed by folks who were clueless re: the situation to hand. A fully qualified Pilot, rather than assisting in the aviating, is doing a checklist that arguably has no bearing on the current problem(s). Additionally, the procedure requires to distract the PF from his focus?

Here is an identified evidence of the Airline, the Manufacturer, the a/c, and the F/O distracting the recovery. At all times by the book, or memory of the book. PF and F/O were writing a new book, and the old book was horning in, inexcusably.

So in preventing the popular conclusion that all responsible parties were remotely engaged in sabotage by reflex, perhaps the authority will give it up?

Secrecy is Power, make no mistake, and at some time, even the apologists for the archaic dance of power will have to become vocal. Other than to say, "it is complicated".

Thanks to ST27
bear

000tfm000
31st May 2011, 14:35
Some people are better than others at maintaining good situational awareness. I would not belittle training and experience. But even very experienced pilots can become disorientated, as indicated by many sad examples among the accident investigation reports I have studied over the years.

Therefore, IMHO, any instrument which might work counter-intuitively in unusual circumstances, significantly increases the risk of disorientation and its associated consequences if those unusual circumstances should arise.

It remains my tentative view that the stall warning (the one at 2h10min51, perhaps; but mainly the one at 2h1202-17) could well have seemed to indicate that the nose-down inputs were for some reason causing the aeroplane to enter a stall, so discouraging the PF from developing the very inputs which might have led to an exit from the stall.

According to the preliminary report the angle of attack "n’est pas présentée aux pilotes": ie, the instruments did not include an AoA indicator. No longer trusting the airspeed or other indicators ("je n’ai plus aucune indication", and "on n’a aucune indication qui soit valable") it may have seemed to the PF that he faced two risks: going too fast for the airframe, or going too slow for the AoA. He seems to have discounted the second of those risks despite the stall warnings. So stated, this was an irrational response. Therefore, it is probable that something made it appear rational at the time. I suggest that he discounted it partly because of the stall warnings or, rather, because of the timing of the stall warnings and their seeming linkage to his nose-down commands.

Razoray
31st May 2011, 14:41
As to why they did nothing for two years, consider that they were told that there was no safety problem by both the manufacturer and the regulator, and they must have agreed, so why do anything? It's not as though pitot tubes are that expensive when compared to other costs. It was only after a few other incidents that they took action on their own to start the replacements.

Not so fast....Air France was well aware that the pitot tubes where a problem and sat on there hands. Yes, they had ordered them, but in hindsight too late. The fact that AF pilots refused to fly with the Thales pitot tubes after the accident because they were "aware of the problem" suggests that AF was not listening to there own pilots, or the pilots kept quiet...

bearfoil
31st May 2011, 14:44
000tfm000

For the present, the times are merely landmarks, suggestive only of snapshots of aspect, response, input, etc. Just prior the Stall Warning that the pilot is rumored to have disobeyed, he is trending out of a high deck angle, and accelerating. This is the result of a Stall, and he will have known that he is in a Stall. Now you may argue that the alert (only an alert) has dissuaded him from continuing the recovery. Given the sparse frame work of such an argument, I will say that to be 'dissuaded from continued recovery' in the midst of physical cues that affirm it, defames our PF further.

Counsel?

Zorin_75
31st May 2011, 14:46
It remains my tentative view that the stall warning (the one at 2h10min51, perhaps; but mainly the one at 2h1202-17) could well have seemed to indicate that the nose-down inputs were for some reason causing the aeroplane to enter a stall, so discouraging the PF from developing the very inputs which might have led to an exit from the stall.
The one at 2h10min51 happened well over 60 kt, so there it wasn't switching back on from a deactivated state.
The second one was, but here no further information about what happened in the next 1m30s is given at all. Maybe he was discouraged, but maybe he kept pushing ND to no avail. We simply don't know because the report doesn't say.

shogan1977
31st May 2011, 14:50
From ST27:Once descending, the rate of descent didn't change, so passengers would have only sensed that the nose was pointed up, somewhat like an initial climbout on takeoff on say a DC-10 or 757. There also would have been heavy buffeting. Given that they were flying at night in a storm, the passengers would have had no outside references to know what was happening, and would not have known they were falling. A clue would have been the change in cabin pressure, but how many passengers would connect that with rapid descent?If like me you click on the flight map when woken by turbulence, you might notice a drop in altitude/airspeed...

From ST27:More rubbish from Der Spiegel. Air France was in the process of changing out the pitot tubes. They received their first shipment of replacement parts a week before the accident, but had not applied them to that particular aircraft.Yes, but as you yourself point out they waited two years to do so because EASA told them, quote: "...[that it saw] no unsafe condition that warrants a mandatory modification of the Thales pitot tubes." So whether you blame AF for ignoring the soft Airbus recommendation, or AB for its soft recommendation, or EASA for its hard statement, clearly when even the manufacturer of a part says its a problem these things should not happen. EASA should be focused on one thing only - SAFETY. At least EASA - unlike the FAA - is not operator funded, so it has no excuse.

ST27
31st May 2011, 14:55
A number of news articles have stated that the PF was the relief pilot, who was the youngest of the crew, had the least amount of experience on type (800 hrs), and the least total flying time. If that is true, and with the captain going for rest, that would leave the FO as PNF. The FO had the most time on type of all the crew (4500 hrs).

None of the BEA reports have stated who was flying at the time of the upset. Perhaps the media obtained the information as a result of a leak. However, this arrangement seems odd to me.

Can anyone familiar with how work would be assigned on trans-ocean flights comment on whether this would be a typical assignment, given that they were about to fly into the ITCZ?

matthewsjl
31st May 2011, 15:00
For example, there is not enough informations to understand why the A330 climbed and stalled at 38 000 ft :

> the pilot gives «ordres à cabrer» (pitch-up orders)

> then the PF gives «ordres à piquer» (pitch-down orders)

Actually, I believe there is enough information to determine why the aircraft entered an initial climb after the disconnects - the pilot commanded it to.

Now, I also think that the report is missing some information but the BEA has shared when power settings changed. After the initial AP/THR discconect, no mention of a power change is made - so it is probably at the setting for FL350 and M0.8. The first input is a pilot commanded climb with a max recorded rate of 7,000ft/min. By the time they reached FL375 nose down had reduced that rate of ascent to 700ft/min (I believe that the plane was still climbing at that point albeit much slower than initially).

Without an increase in thrust, there is a trade of speed for altitude. Most likely pilot commanded but turbulence/updrafts may have played a part too. I think if there was an intent to climb over any weather then a thrust setting change would have been made by the PF and none is noted by the BEA.

At 2h10m51s the stall warn sounded. It probably hasn't stalled at this point - the BEA indicates the last 3m30s were stalled and the recording finished at 2h14m28s. That makes the stall a 'fact' at 2h10m58.

John.

shogan1977
31st May 2011, 15:01
According to this article, Bonin was the PF. As you suggest this could very well be pure speculation on the part of the journalist - or possibly based on a leak? 'Baby' pilot at controls of doomed Air France Airbus | The Australian (http://www.theaustralian.com.au/business/aviation/baby-pilot-at-controls-of-doomed-air-france-airbus/story-e6frg95x-1226064924740)

Mr Optimistic
31st May 2011, 15:04
Deliberate climb to get out of icing but with no reliable speed mismanaged thrust ?

Elledan
31st May 2011, 15:07
Elledan, the Dutch news site is wrong. To be sure of climbing over an ITCZ "lightning storm," the AF flight crew would have to have assumed they might well have to climb as high as 55,000 feet or so, and to do that, they'd have needed the Space Shuttle, not an Airbus. Their sudden climb to 380 had nothing to do with any attempt to top a thunderstorm.

Yeah, that's what I figured. Pilots can fly around a storm, but they can't fly over one. No idea why this news site (usually very reputable) made such a big blunder. Their claim struck me as odd as it was never coined as a possibility elsewhere, especially not on this site :)

The current conclusion seems to draw towards pilot error with equipment failures and gaps in training as likely contributions. The nose-up inputs especially seem beyond merely curious. I really wonder whether there might be anything about that on the CVR.

A37575
31st May 2011, 15:15
Can anyone familiar with how work would be assigned on trans-ocean flights comment on whether this would be a typical assignment, given that they were about to fly into the ITCZ?
ST27 is online now Report Post Reply

The trouble is when a pilot is given "a leg" which is more or less what happened when the second officer was PF after the captain had gone down to have some shut-eye, there seems to be a attitude that as PF he hangs on to the decision making and controls even though the real first officer is more qualified and senior in succession. "My leg" is not carte blanche to be in command unless of course the captain is PF.

Clearly in the Air France case the experienced first officer as PNF should have taken control immediately things went wrong. Of course there was no guarantee the F/O could have saved the aircraft either but the political correctness of "my leg" needs to be examined. In my era the captain would at his discretion offer the F/O a take off and/ or a landing. It was never a case of "your leg" with all that implies. It was always the captain's "leg". Every sector was under the command of the captain and supported by his F/O.

Now it is almost seen as an insult to the first officer if the captain decides to take over control of the F/O's "leg". In the case of the Air France accident it is this politically correct mind-set that may have caused the real first officer to assume the subordinate role as PNF while the second officer lost control of the situation.

CI54
31st May 2011, 15:28
This is indeed an interesting observation, worthy of a study in itself. Where I work, we have a general inkling that CRM has gone 'bonkers'. It certainly was baffling to me why the Captain did not jump back into the seat and 'take over', until explained this way...

ATC Watcher
31st May 2011, 15:49
Yeah, that's what I figured. Pilots can fly around a storm, but they can't fly over one.

Some unfortunatelty try to do it , it ends up badly most of the time.

In my years as ATC the one I remember best was a transatlantic bound 747 from a major European airline (now defunct) who decided against the 60-80NM dogleg that everyone else was doing to avoid a line of CBs above Belgium. He asked to climb to FL390 to keep its route , then when above dropped down 5 or 6 thousanfds feet right inside. His voice was shaken afterwards. The incident report must still be out somewhere.

2 weeks a go an A320 tried the same thing above Germany, with same results. 3xmayday, dropped 4000ft etc..
Rare events , sure ,but not unheard of.

Tmbstory
31st May 2011, 17:19
A37575:

It is not a right that every other leg belongs to the F / O or 2nd Captain.

It is the Commander's decision to allocate the legs, if he wants to.

The decision of the Captain, to go to the "bunk" so early in the flight seems strange to me, however he must have had a reason.

wiggy
31st May 2011, 17:36
The decision of the Captain, to go to the "bunk" so early in the flight seems strange to me, however he must have had a reason.

Not really, as I think has been mentioned earlier in the thread if it's pure timing we're questioning here then if the Captain had "second break" the timing makes sense.

On the broader issue of him being "off watch" during the ITCZ crossing, personally, I think you have to take into account the fact that he left two fully rated pilots up front - not cruise only copilots. If we're saying a Captain shouldn't ever leave the Flight Deck because inclement weather is forecast in the cruise how do we suggest handling say, traversing Asia or Indonesia during the monsoon season or the North Atlantic if there's forecast of occasional severe CAT all the way across the pond......two Captain ops/no in flight rest :eek:????

(BTW am I alone in often not being able to see the last page of the thread?)

grimmrad
31st May 2011, 17:43
Maybe a dumb question from a dumb SLF - wouldn't it make sense to have a mechanism that blows into the Pitot tube from the inside to test if it is clogged? If there is higher resistance than its clogged and disregard readings. Maybe it can also be cleaned that way...?

HundredPercentPlease
31st May 2011, 18:24
Some people are better than others at maintaining good situational awareness. I would not belittle training and experience. But even very experienced pilots can become disorientated, as indicated by many sad examples among the accident investigation reports I have studied over the years.

Therefore, IMHO, any instrument which might work counter-intuitively in unusual circumstances, significantly increases the risk of disorientation and its associated consequences if those unusual circumstances should arise.

It remains my tentative view that the stall warning (the one at 2h10min51, perhaps; but mainly the one at 2h1202-17) could well have seemed to indicate that the nose-down inputs were for some reason causing the aeroplane to enter a stall, so discouraging the PF from developing the very inputs which might have led to an exit from the stall.

I too shall declare my interest: A320 Captain.

I really don't know where to start with this thread. So much noise, so little signal. The number of red herrings and long irrelevant side tracks is so great that no one can even start to address them.

The PF quickly and correctly diagnosed the situation. Loss of airspeed indication, resulting in AP/AT off and Alternate Law. He then incorrectly pitched up to 10° until the AoA was just 2° from the stall.

In this perilous position, the AoA increased again to 6° and the aircraft stalled. The response was incorrect with TOGA + pitch up.

So, two apparent errors. So much has been said about the wrong procedure being used (TOGA + pitch up is used in many other procedures) and a lack of training that I won't bother. But here is something frightening:

Most older Airbus pilots have done their time in cranky old jets and turboprops, where you fly by pitch. Everything is done by pitch settings - choosing, setting, adjusting, waiting and so on. However, in the world of the safety committee it is fine to pluck young lads straight from a Seneca and place them into an Airbus. To mitigate the risk, the flight director must be on at all times. Now all the cadet has to do is put the square in the centre of the cross. Never has a pitch been noticed nor noted.

I asked 5 first officers in the cruise to look me in the eye and tell me what pitch we were at (2.5°). 4 cadets answered between 5° and 10° :ooh:, and one ex TP guy answered correctly at 3°. Not much of a sample, but indicative I suspect.

The Airbus is a fine aircraft. It is conventional, and simple. On top is a thick layer of cotton wool, that should protect us from our silly mistakes.

Once the cotton wool is removed, we are back into a simple jet. The snag is that with the current drive to train/recruit people as quickly and cheaply as possible, not one of the recent arrivals has ever flown in "simple jet mode" (by pitch and thrust). Incredibly in our airline it is now even prohibited to take off with the flight directors off.

I feel sorry for the two FOs on the flight deck. Without the FD they will have been in new territory. Without the airspeed, it is no time to have to guess pitch settings and develop a strategy to keep the thing in the air.

I hope the airlines have a good think about this. I imagine the safety departments will, but nothing will happen due to the cost of recruiting people with experience on conventional types.

PS: Below 60 knots I imagine the stall warning is inhibited because there is not enough airflow over the AoA vane to make it accurate and trustworthy.

PPS: Has any Airbus pilot here ever actually heard the stall warning in the sim?

jcjeant
31st May 2011, 18:30
Hi,

(BTW am I alone in often not being able to see the last page of the thread?) NO ... methink it's a bug in the forums
Sometime it's more than 1 false "last page" :)

wiggy
31st May 2011, 18:32
I asked 5 first officers in the cruise to look me in the eye and tell me what pitch we were at (2.5°). 4 cadets answered between 5° and 10°

You're right, that's frightening.

Yellow Pen
31st May 2011, 18:40
To mitigate the risk, the flight director must be on at all times. Now all the cadet has to do is put the square in the centre of the cross. Never has a pitch been noticed nor noted.

Blimey, which airline do you fly for? I'll make a note not to fly with them as there appears to be some serious shortfalls in your training department.

jcjeant
31st May 2011, 18:49
Hi,

There also would have been heavy buffeting. Given that they were flying at night in a storm, the passengers would have had no outside references to know what was happening, and would not have known they were falling. A clue would have been the change in cabin pressure, but how many passengers would connect that with rapid descent?Maybe all this is right ...
But passengers also have ears to listen ... and I am than most (at least those who were not asleep or woke up) will have noticed changes in engine speed .. and it will have more of a worry about .. even if they did not know that the plane was heading towards the sea
Moreover, I wonder what that could be displayed on the seats screens .....

pattern_is_full
31st May 2011, 19:02
(BTW am I alone in often not being able to see the last page of the thread?)

Aside to wiggy - No, you aren't alone. But it just a forum housekeeping thing. As Page 59 (e.g.) gets nearly full, an empty Page 60 gets created. But until the posts actually flow over to page 60, you can't get to it (and there's nothing yet to see anyway).

timpara
31st May 2011, 19:13
PS: Below 60 knots I imagine the stall warning is inhibited because there is not enough airflow over the AoA vane to make it accurate and trustworthy.

Well they were descending, stalled at ~120 Knots with the AOA sensors exposed to the airflow, so the sensors should have been providing useful info. Can anyone explain therefore the logic in inhibiting the stall warning with no weight on wheels? Maybe not the first hole in the cheese....

milsabords
31st May 2011, 19:21
It is not a right that every other leg belongs to the F / O or 2nd Captain.

Do the number of hours an FO has flown as PF count for his/her career progress ?

HundredPercentPlease
31st May 2011, 19:24
Yellow Pen,

I over egged. The flight director must now be on for take off and initial climb out. It may be off for an ILS if conditions are suitable, and will be off for hand flown visuals.

However with the level of inexperience we now have, not many captains will be so happy at the thought of a <500 hour pilot flying a raw data ILS, when most approaches and landings with a full house of aids can be just a tiny bit "variable".

We have an industry wide reputation for having an excellent training department. However we (like many other airlines) now refuse to recruit experienced first officers, and restrict ourselves to Seneca -> Airbus low hour contract first officers. Hence my point - many recent Airbus pilots may have no experience of flying a jet on pitch and thrust alone.

milsabords
31st May 2011, 19:28
grimmrad: wouldn't it make sense to have a mechanism that blows into the Pitot tube from the inside

Already discussed in the Techlog thread.

pattern_is_full
31st May 2011, 19:33
I'd say if a 200,000-kilo plane is in the air, and at less than 60 kts, it is stalled, regardless of whether the AoA vanes are trustworthy at that speed.

The Stall warning logic should be "if the plane is not on its wheels, and the AoA vanes indicate a stall, then the warning sounds. It ALSO sounds if the plane is not on its wheels and the AoA vanes have reached their maximum reliable point (even if no longer trustworthy)."

I'll concede that an A330 in the air at 60 kts is improbable - but the improbable is what warning systems are intended for.
_________________________

RE: the reported quote from the Captain "We're in a stall, REDUCE power and pitch." I take it that has to do with the A330's low under-wing engines? A high power setting (or rapid power increase) would cause more pitch-up, making it harder to lower the nose and break the stall? We've seen that noted in the case of 737 stalls or go-around incidents.

Usually, stall recovery involves INCREASED power.

Me Myself
31st May 2011, 19:37
Hundredpercent

You nailed it ! This is exactly what it is along with a twist of over confidence.
I'm sorry but 2 F/O's at the front, even if qualified ( WTF does it mean anyway ? ) is not the same as a skipper and a F/O.
When the captain is on the flight deck, there a clear chain of command. There is also at least 15 years difference of dealing with crappy flight conditions and I'm sorry, like it or not, that makes a hell of a difference.
It's become a very touchy issue where F/O feel insulted whenever they're told they are not as " good " as the old man in the left hand seat.
Again, it has nothing to do with " good " or " bad". Commnanding a flight is a job that one learns and creams with experience. A sprinkle of humility sweets it nicely too.
What some airlines need to do is to acknowledge there is a gap that needs to be filled and very pronto.
Lufthansa has a Senior First Officer training syllabus where emphasis is put on leadership and left hand seat handling of the aircraft in emergency situations. The roles are very clear when the Captain is in the bunk.
Others have second first officer which is another way of clearly stating who does what under who's authority.
So to say that 2 fully qualified pilots are the same is just ludicrous.

If the debate remains an egotic one, I'm afraid we're not going to very far and to finish : Yes !!! I think the Captain has to arrange his breake so as to be in his seat for the tricky part of the flight and as to 447 I am damn sure the outcome would have been very different had the Captian been on the flight deck for the reason Onehundredpercent so elloquently explained.

mross
31st May 2011, 19:50
Surely the IAS only fell to 60 knots during the icing of the pitots? I don't think the a/c's true airspeed ever fell that low or am I wrong? An in-flight IAS of 60 knots will always be considered UAS if I understand the FBW 'logic'.

wiggy
31st May 2011, 20:07
Yes !!! I think the Captain has to arrange his breake so as to be in his seat for the tricky part of the flight

A colleague of mine brought a 744 back to Europe from South America on the very same night as AF447, on one of the parallel airways if I recall his account correctly. He had 10,000 plus on 744s, a South Atlantic regular and he reckoned that in his HO the sigmet chart showed the ITCZ was no "trickier" than normal.

So what are we defining as "tricky, and therefore captain must be in his/her seat weather"? Look at a Longhaul sigmet chart for, say, Asia and the subcontinent in the monsoon season...where's the "tricky part of the flight"? Probably starts at SIN maybe ends at Karachi, and then there's the "tricky" high ground and the "tricky" comms, around Kabul, oh and then after that the inevitable CBs (with associated severe turbulence of course) around Moscow or the Crimea and the dire warnings about being very careful if deviating in Russian airspace.."tricky" or not? Again a sigmet chart for the North Atlantic will quite often show that the NAT tracks are planned to pass through or very near to areas of forecast Moderate to Severe CAT..so by some definitions the whole of the Atlantic could be "tricky" on some nights.

If your are seriously going to mandate/insist that the Captain must be in his seat for the "tricky part" of every flight, irrespective of the qualifications and/or experience of the other pilots, how are you going to do it/pay for it? BTW I've no problems with two captains on a three pilot augmented crew if that's your answer :ok:

captplaystation
31st May 2011, 21:05
Wiggy,

You may, perhaps, be being facetious with your suggestion, but, as a Captain, I think it would increase my chance of sleeping from "no bloody way" to "yeah I might nod off" were it to be adopted.
My current ops involves moderately long 2 sector night ops with the "official duty" involving me "sleeping":D for a bit in Row 1-3.
Well,let me tell you, I don't, I do go back,so as not to ruffle feathers, and probably I never will manage to zzzz, so it is as well that I don't make too many of them in a month.
In God (& Pratt & Whitney, what about CFM?) we trust, the rest? :hmm: := NFW ! !

JJFFC
31st May 2011, 21:08
Quote:
(BTW am I alone in often not being able to see the last page of the thread?)
Aside to wiggy - No, you aren't alone. But it just a forum housekeeping thing. As Page 59 (e.g.) gets nearly full, an empty Page 60 gets created. But until the posts actually flow over to page 60, you can't get to it (and there's nothing yet to see anyway).
http://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/statusicon/user_online.gif
(http://www.pprune.org/newreply.php?do=newreply&p=6485561&noquote=1)Who designed this (to create a page nobody can read and wonders why) ?:ugh:

Is it Boeing or Airbus ! :{

gulfairs
31st May 2011, 21:15
When 80% of first officers think like that , surely they must be a product of the "Sausage Factory" training system.
There are many of these type of training schools in the antipodes.

crippen
31st May 2011, 21:17
The 'extra' pages are for the posts that the mods have deleted. The trick is to look at the post number of the last post on the page. If the number of the post is devidible by 20,chances are there is another page to read!;)

ie this was the last post at the time of posting.

JJFFC
31st May 2011, 21:28
Hi Meccano

JJFC
If you KNOW an instrument is faulty - are you seriously suggesting we follow it? I hope I'm misunderstanding you here, because any pilot is potentially 100% more reliable than a faulty instrument!
And unfortunately it's not always clear cut. Contradictory indications often occur.
Which instrument to believe then?? My point is statistics:


An instrument is 99.99% reliable at min
A pilot is 97% reliable at max (this is why a plane has automatic protections)

The PF on the AF447 sees:


vertical speed : -10000
speed : no data
pitch : > 15°

What should he bet on :


no speed, therefore he doesn't believe his instruments : 0.01% x 93%
he stalls : 99.99% x 93%

Sincerely yours.

Right Way Up
31st May 2011, 21:32
IMHO I think flight data monitoring has been a factor in the demise of flying skills. Unfortunate as it is, the same experienced Captains who used to let f/os fill their boots and learn under their informed guidance, now are sick of newbie flight managers who use the tool to berate the smallest indiscretion and tend now not to take the risk. Sadly I believe the pilotless flight may as well be introduced.

Me Myself
31st May 2011, 21:40
[QUOTE][If your are seriously going to mandate/insist that the Captain must be in his seat for the "tricky part" of every flight, irrespective of the qualifications and/or experience of the other pilots, how are you going to do it/pay for it? BTW I've no problems with two captains on a three pilot augmented crew if that's your answer
/QUOTE]

Wiggy, I don't think you read my post with the attention it deserves ! :))

In my dreams, yes ! I would love to have a second captain. By the way, that's what Emirates does on long sectors to Australia.
If not, at least, I want a Senior guy who is command trained, like Lufthansa.
I am not at all satisfied, and let me tell you I am not alone, with the system we have.
So if the tricky part turns out to be most of the flight, chances are...............I'll be sticking around for a good chunk of the flight. Call me a woos, I don't care.
I was in the bunk only a couple of days ago as I will be tonight and couldn't help thinking about my colleague, lying there in the dark and having to rush to the cockpit and try to make sense of what he was handed. I too, would have been toast on that one.
At the end of the day, you don't know the fellows you're flying with and they may or may not give you a good impression at sign on, hard and cruel fact is this : 7000 ft/ min at FL350 blasting off to 380. If you can sleep with this, good on you ! I can't.

EGMA
31st May 2011, 22:15
The common thread throughout is that 'even an ab-initio PPL should have been able to recognize and recover this stall'.

In my flight testing I have had the experience of recovering from a fully developed stall on partial panel when the b$tard sitting next to me has applied full aft trim. Easy, if you know what the aircraft is doing.

It is a different kettle of fish if the the manual tells you, that for no speed info, you apply nose-up and power. At altitude this is going to take you to a stall, then, with (hidden) full aft trim, no stall warning and a TOGA power pitch-up couple you are probably flying an unrecoverable aircraft.

These pilots weren't stupid, there but for the grace ....

JJFFC
31st May 2011, 22:26
EGMA : In my flight testing I have had the experience of recovering from a fully developed stall on partial panel when the b$tard sitting next to me has applied full aft trim

According to you, in the AF447, was the "b$tard" a human factor, the plane or the weather ?

ExSp33db1rd
31st May 2011, 22:41
My last employer mandated a second Captain for an augmented crew, and we also had a Flt. Eng., someone with aviation experience on the flight deck who might just be thinking outside the box relative to a pilots' thoughts, and also wasn't physically involved in handling the hardware in the same manner as the pilot, so could look at a problem from a different angle.

But that costs money, and we must always genufluct to Progress.( and profit )

The last words recorded from another accident where the pilot was confused as to the information he was receiving was - look at the standby ( which was giving the correct info. ) shouted by the F/Eng. Too late unfortunately, which of course raises issues of P.C. culture and CRM as well.

EGMA
31st May 2011, 22:42
In my case it was the examiner, in their case in the absence of a trim wheel ....?

In either case relaxation of nose down can, or will, lead to a second stall ...

stepwilk
31st May 2011, 22:52
Who designed this (to create a page nobody can read and wonders why) ?

I think most of us figured it out a long time ago.

SaturnV
31st May 2011, 23:07
Wiggy, a 744 on UN873, the same airway as AF447, and preceding it by about 20 minutes deviated around the heaviest weather. A 340 following AF447 by 12 minutes also deviated. The next flight following the 340 was AF459, which deviated to both the left and right to fly around the MCC. AF459 deviated by 70 NM to the right of the track.

HarryMann
31st May 2011, 23:39
..........Is there any way of trimming the stabiliser really "manually" ? Arhhhhhggg!

Look, if you haven't read much of the thread you shouldn't be posting and wasting more time & space having your repeat questions re-answered :=

It was explained barely a dozen pages back (for about the 5th time!!) :ugh:

xcitation
31st May 2011, 23:47
What would cause PF to keep the A/C in what I would summarize as a flared landing stall from FL380 to impact.
There is surely a missing piece here. Clearly the BEA statement is an extreme simplification of the facts. It implies that the pilots did everything professionally i.e. handled the a/c correctly given their training. Logically the cause must lie somewhere other than the pilots?

Presumably they did not ignore/neglect the flight instruments?
Were the flight instruments degraded more than just losing the Airspeed that the BEA is yet to release.
Did significant ice build up degrade the handling character of the airframe.

One thing is clear. A continuous tone stall warning would have helped as the plane had effectively "flat lined". The stall warning should not disable as the speed decays, if anything it should get loader.

IMHO the missing piece of why they sticked back is the largest hole in the swiss cheese. I was hoping for some resolution from BEA or the forum. However the statement has raised more questions than it has answered.


The other holes in the swiss cheese are a grey area and open to argument.
AF chose to not update pitots aggresively as some other airlines.
Prior to departure the Captain chose a flight path directly through the storm whereas the subsequent flights (Iberia and Lufthansa) took on extra fuel and significantly deviated.
Captain chose to take bunk rest during the more challenging part of the flight.
Airbus training in excursions outside the normal flight envelope and outside normal law are under represented.

DeltaT
1st Jun 2011, 00:16
I presume all data from all sensors gets recorded on the Flight Data Recorder, so there will be information saying they were in a stall and AoA when in fact due to frozen probes they, at the start at least, were not in a stall and the AoA is incorrect. The only correct information being pitch and power the same as what the pilots would have?
Why this has been released to the media in the way it has seems very poor management.
I have sat here reading as many posts as possible, it is a shame the pilot concerned has been referred to as a Baby and its been jumped on by all and sundry. I wonder how you would cope given the situation of long haul and in the frame of being in a routine. Unreliable airspeed is hard enough to cope with, but in a storm cell, never mind later on when your tail rips off -which the latter I haven't seen anyone make reference to yet.

Re 2 previous post, I seem to recall something about this specific route being tight on fuel in order to be achieved, and this is the reason they did not deviate around the storm, they simply couldn't spare the gas??
Or much simpler, they missed it in the departure brief and missed the trick of turning up the brightness on the weather radar so saw nothing! (latter been done before)

Me Myself
1st Jun 2011, 00:36
never mind later on when your tail rips off -which the latter I haven't seen anyone make reference to yet.

The tail didn't rip off while in flight but upon impact. That was one of the first findings 2 years ago.
Short of fuel ? Pressure ?
All I can say is this : in all the years I have been flying for AF, not once have I been given the " frown " for taking whatever quantity of fuel I deemed necessary.
We have figures as to the cost, that's all. The rest is entirely left up to you, your experience and judgement.
If I ever felt pressure......it was the one I was puting myself under.

AF chose to not update pitots aggresively as some other airlines.
Prior to departure the Captain chose a flight path directly through the storm whereas the subsequent flights (Iberia and Lufthansa) took on extra fuel and significantly deviated.
Captain chose to take bunk rest during the more challenging part of the flight.
Airbus training in excursions outside the normal flight envelope and outside normal law are under represented.

:confused::(

bubbers44
1st Jun 2011, 00:46
Once enroute you can always get deviations for weather so I am sure all the other airliners on the same route did that. It still looks like the final report will be the repeated Airbus pitot/static problems that were slow in being corrected. The copilots should have been able to handle unreliable airspeed with no problem. Everybody wonders why the PF pulled back and zoomed to FL380 and entered a deep stall.

No airliner I have flown says to pull back, it says to hold appropriate pitch and power for weight and altitude. I know the Airbus has no feedback of what the other pilot is doing so complicates things.
Also the interim report leaves out so much information they have for some reason so even though I am sure they know what happened, we don't with the lack of information. The CVR will tell a lot of the story and the FDR will tell the rest when they release it.

Ian W
1st Jun 2011, 02:39
Late but hopefully useful
This thread is galloping forwards so fast that I'm replying to something three pages ago, but it was only a few hours ago, and it needs answered because it is another daft blind alley.

Someone said:
Quote:
I can't believe anybody would certify an airliner that is stalled but the stall warning mutes because the pitot static system senses less than 60 knots. That is nuts.
I think you will find that is completely normal, and even a microsecond of thought will tell you why. Think "parked on the taxiway". There's a strong chance the wing is fully stalled, but we'll supress the stall warning until we've got some speed up, thank-you.


I think that you will find it is normal to use an undercarriage microswitch so that when the aircraft is 'sat on the runway' the weight compresses the oleo and the microswitch says 'ON' when the weight is off the undercarriage the microswitch says 'OFF'. This is used for OOOI by ACARS but apparently is too simple for the Airbus design team who instead put in a system that was based on their assumption that at less than 60 kts the aircraft will be on the ground.
That was an incorrect assumption which in this case may have been one of the series of errors that ended with a destroyed aircraft.

LoboTx
1st Jun 2011, 02:45
Unless I skipped a page somewhere, I've not seen this posted. Apologies if it has been.

75 additional bodies recovered from Air France crash after 2 years - CNN.com (http://www.cnn.com/2011/WORLD/europe/05/31/france.jet.crash/index.html?hpt=hp_t2)

This is contrary to decisions I thought were made weeks ago.

Graybeard
1st Jun 2011, 03:10
I wish somebody intimate with AOA vanes would come on here and explain authoritatively why stall warning shuts off below 60. It's a physical limitation. Maybe one of you whiners could come up with a design that's better than the present one, which is nearly as universal as the pitot tube. How often has the present design even been criticized in an accident investigation, let alone blamed?

Razoray
1st Jun 2011, 03:39
A question for all the experts....

There has been no discussion of the lack of a distress call from AF447. Does this indicate the lack of situational awareness on the flight deck as they where struggling with the jet? Is it SOP to put out a distress signal when the :mad: is hitting the fan, regardless of where you are? Where the pilots to busy to put out a call, or too confused?

thermostat
1st Jun 2011, 03:40
Delta T,
if you have to deviate around a large storm system and by doing so you run short of fuel, then you make an en route stop for fuel. It's that simple. They could have stopped in the Canaries or Lisbon for fuel, but now they will never have the chance of taking fuel ever again. Please pay attention to the fact that other flights took extra fuel, deviated and arrived safely. Flying is serious business.

EGMA
1st Jun 2011, 03:56
Quote:
Who designed this (to create a page nobody can read and wonders why) ? I think most of us figured it out a long time ago. Yep, but it took me longer than 3.5 minutes ...

MountainBear
1st Jun 2011, 04:03
There has been no discussion of the lack of a distress call from AF447.


Aviate, navigate, communicate. They hadn't got past the first which is why you see no discussion of the third.

jcjeant
1st Jun 2011, 04:38
Hi,

Fuel ?

Prior to departure the Captain chose a flight path directly through the storm whereas the subsequent flights (Iberia and Lufthansa) took on extra fuel and significantly deviated.
Delta T,
if you have to deviate around a large storm system and by doing so you run short of fuel, then you make an en route stop for fuel. It's that simple. They could have stopped in the Canaries or Lisbon for fuel, but now they will never have the chance of taking fuel ever again. Please pay attention to the fact that other flights took extra fuel, deviated and arrived safely. Flying is serious business. The BEA report:
The take-off weight was 232.8 t (for a MTOW of 233t), including 70.4 t of fuel.Do you know the extra fuel quantity take on board by Iberia and Lufthansa ?

The AF447 flight had enough fuel for change his route.
Read also the two BEA preliminary reports.

Bodies recovered
This is contrary to decisions I thought were made weeks ago. Those decisions were nullified by another .. one week ago when the results of ADN research on the two firsts bodies recovered were positive

Distress call

Where the pilots to busy to put out a call, or too confused?

You answered yourself ....

wallybird7
1st Jun 2011, 06:07
"Everybody wonders why the PF pulled back and zoomed to FL380 and entered a deep stall."

I never read it that way. My read is that they were unable to climb because the temperature did not fall. Never any indication that they "planned" a climb.

I read NOT that they climbed, but they ascended, or, they were pushed, or, caught a severe updraft, and then wound up at 38,000 in a nose up condition, at below 60kts and thus literally out of control because at that time the controls would be inneffective.

Which is consistant with being in a thunderstorm.

Rotorgoat8
1st Jun 2011, 06:10
Right on!! bbg (Page 51)

Didn't we go through this with the Dominica 757 crash?? Problem is the warnings don't shut up--goes back to a CV-580 crash in the midwest-they ingested a bird right at rotation and the engine autofeathered-the pilot was a veteran but the speaker was shouting "Pull Up, Pull Up................." he never got back the speed he need to recover - because?? Yea - He pulled up. I memorized the locations of the Aural and Speaker CB's on the 757 so I could shut them up and keep my head straight during what was obviously a warning malfunction. What's happening here is the Automation is not assisting pilots anymore -- pilots are trained to assist automation = Bad Formula! Standby for more of the same in the future until they get the formula changed-if ever!

pattern_is_full
1st Jun 2011, 06:30
@ wallybird7

At the moment the incident began.....(from the May 28, 2011 update report)

"From 2 h 10 min 05, the autopilot then auto-thrust disengaged and the PF said "I have the controls". The airplane began to roll to the right and the PF made a left nose-up input....The airplane’s pitch attitude increased progressively beyond 10 degrees and the plane started to climb."

As you say, no climb was planned - but that doesn't rule out an inadvertent climb induced by pulling the stick while correcting the right roll.

The report mentions the pilot raising the nose in the first seconds after taking the controls. It notes turbulence events. It doesn't mention evidence of an updraft.

TheShadow
1st Jun 2011, 06:47
I sorta took exception to the presumptive tone of the article and some private correspondence between journos in the same ilk....that I was copied in on. I decided to re-orient them (late at night after a half-bottle of brandy) - so it may not be comprehensive. If you know of any points that were missed, pls post. Apologies for length but need to be comprehensive. I'm sick of defenceless dead pilots having to carry the can.
Gentlemen
*
You oversimplify their predicament. You (and so do we all) need more data. However it's also obvious that useful data was exactly what the AF447 pilots lacked during their deep-stall descent - because of the peculiar aspects of the pitot freeze-up during high altitude cruise..... and its effect upon the subsequent post-zoom stall.
*
One of the characteristics of an approaching or incipient stall that pilots are trained to respond and react to is "low and decreasing" airspeed (even if they have no stall warning hooter or "cricket"). However they wouldn't have had any airspeed indication during their deep-stall descent with an iced pitot x 3. Nor did they have an angle-of-attack indication..... i.e. even though the A330 is equipped with an AoA vane to feed the automation (including the stall warning system), the pilots don't warrant a gauge of any sort. So what did they have for identification of (and recovery from) a stall? The real answer is precious little - by way of overt display or training fallback.
*
They had a source of pitch attitude. However consider that most approaches to the training one-g stall is made in level flight at a speed reduction rate of circa one knot per second. Thus, at the point of the incipient stall, where pilots are taught to initiate recovery (i.e. at the stall buffet), the additional cue on an ADI or visual horizon*is a high nose attitude (typically around +15 degrees).*But in a deep stall entered ballistically at high altitude post-zoom, the attitude in pitch during descent with max power (due pitch-up effect of underslung engines) would approximate the straight and level attitude of around 3 to 5 degrees nose-up. Thus they were robbed of most all cues that could clue them that they were in fact in a stall. They wouldn't have been aware that their auto-trimmed horizontal stabilizer trim was NOW unavailable - and stuck at its maximum of 13 degrees nose-up. If nothing else, it was that THS (trimmable hoz stabilizer) that would've held them in a stalled pitch attitude..... regardless of any subsequent side-stick pitch inputs. The THS has the REAL pitch-trim authority at low speed, the elevators are virtually trim-tabs for higher speed refinements.
*
But wouldn't the stall warning be blaring you say? Not necessarily so. It's designed to be discontinuous (a rare concession to the cacophony effect of blaring aural alerts in an emergency). In the factually sparse BEA report, that aspect isn't addressed in depth. The only trigger for the aural stall warning is the AoA and that has a set threshold both to start and to cease. Once they were at around 40 degrees AoA I'd be surprised if it was to be heard on the CVR (see later shock statement of cause of non-recovery below). What about the stick-shaker? It too has cautionary thresholds and they were soon well beneath that triggering band. The A330 wasn't tested for its high altitude ballistic stall entry characteristics - so the instrumentation wasn't available or calibrated to cope. What about the VSI or IVSI/RCDI (rate of descent indicator). It's not very attention-getting and it's probably linear (i.e.in a non-circular) presentation anyway in the A330 (I prefer the round dials for visual attention-getting). It's hard to say what it would have read in a compromised pitot-static system anyway. You must also consider what effect upon the airspeed indicators a 10,000 fpm rate of descent would have on their airspeed read-outs (think rate-of-change of static pressure). The ASI's are reliant upon both a pitot and a static pressure input feed.
*
*Would there have been any tell-tale buffeting? In a word "NO". The buffet in a one-g stall is provided courtesy of the disturbed airflow over the wing hitting the tailplane. At the BEA's stated 40 degrees angle-of-attack, the disturbed airflow would not impinge upon the tailplane. They were going down in an express elevator at around that self-same 40 degrees angle (that they were presenting to the relative airflow). I was surprised to find myself agreeing with one animated depiction on TV of the stalled steep descent event. That's how it would've been in my view - and thus the airflow and airframe buffet wouldn't have been a player in alerting the pilots to their stalled status. It was probably/relatively much quieter than the ambient noise in cruise, even with the engines at TO/GA. By design, in alternate, direct or ABNORMAL Law there is no auto-trim (it discontinued after reaching 13 degs nose-up), no ALPHA FLOOR PROT or ALPHA max (i.e. no max selectable AoA), so the aircraft can be stalled once in extremis - an aspect and consideration that's alien to Airbus pilots. AF447's stall occurred beyond the imagination (also) of the A330 designers or test pilots, at the ballistic apex of a zoom climb with lotsa power set - and at or above its ceiling for its weight.
*
But there were also other complications which I'll briefly mention:
*
a. What actually happened to initiate the sequence of failure advisories and the ACARS spew? Did the auto-pilot self-disconnect after running out of its ability to hold the nose-down force gradient of a horizontal stabilizer being trimmed by the system to compensate for the aircraft being driven ever faster in real speed terms (i.e. accelerated by the auto-thrust, to offset the perceived gradual loss of airspeed from the slowly icing pitots?). If so, then when the autopilot disconnected, the pitch-up would have been involuntary. Any evidence for that? The BEA says "the airplane's pitch attitude increased progressively and the plane started to climb. The PF made nose-down control inputs and alternately, left and right roll inputs." Reflect upon the fact that the one thing the pilot has left once he's apparently lost elevator authority in a pitch-up, is to roll the airplane in order to induce a nose-drop. It's evident IMHO that the post-disconnect pitch-up was therefore involuntary and opposed by the PF. Entry to the post-zoom stall is likely to have been automated.
*
b. A few seconds after the aircraft levelled at 37,500ft at a 4 deg AoA the BEA says: "the stall warning triggered again. The thrust levers were positioned at TO/GA and the pilot maintained nose-up inputs." No real surprise there. They'd zoomed to above their ceiling and the pilot was stick-back to oppose the tendency of the nose to drop at the unknown (to him) low speed. Unfortunately, as a result, the THS continued to trim to max nose-up and the distracted pilots then allowed the aircraft to stall. There's an indication that the lower speeds may have allowed the pitot heat to clear some of the pitot ice....i.e. the ISIS speeds becoming consonant with the recorded PF speed. Report: "As the captain re-entered the cockpit the recorded speeds became invalid and the stall warning stopped" At this point these are evident indications of now having entered into the very low IAS/high AoA deep-stall condition. Distractions of trouble-shooting are the likely cause of the PF allowing the 13 degs nose-up THS (of which he was unaware) to silently promote a stall.
*
c. If the autopilot had disconnected because of ADR disagree parameters being exceeded, then the zoom may have resulted from a post-disconnect overspeed warning and a natural pilot pitch-up response. Whatever the cause of that pitch-up, the auto-trim would've been available and so it was (BEA) - and so it did auto-trim the THS into a fateful 13 degs nose-up (whence it remained).
*
d. How did the captain's arrival upon the flight-deck affect the outcome? Firstly, in a quick urgent scan he'd not have seen the PF pilot's grip upon his sidestick (think about it and compare with what the MS990 Captain saw upon re-entering his Egyptair cockpit). He would've seen no (or low?) IAS displayed and the altimeter unwinding - yet loads of power. 20 seconds after he entered the flightdeck the throttles were placed at idle. At his command? Probably. Did he misinterpret the situation as the aftermath of a high-speed loss of control and thus did he complicate the recovery issue? Probably. Are Airbus pilots generally unfamiliar with the possibility of entering a deep-stall condition at altitude? Probably. Is it never sim practised or preached or does it not rate a mention in the Pilot's Handling Notes? Probably not.
*
e. The BEA mentions that, at A/P disconnect, a sharp fall from about 275 kts to 60kts in the left primary PFD was recorded, then a few moments later on the ISIS STBY insts. Using the analogy of how hail size-growth increases exponentially in the latter part of its fall (due to an ever increasing surface area upon which moisture can coalesce), we can divine that a similar thing was happening to each of the three pitots. Thus, as soon as the pilot made his sharp nose-up side-stick input, the smooth laminar flow into the LH pitot inlet (the only one recorded) would've been disrupted by the pitot's projecting icy excrescences.... causing the 275/60 transitory hiccup. I'd further interpret this as being partial proof that the auto-pilot disconnected primarily because of the elevator (nose-) download it was carrying due to the discrepancy between the aircraft's actual speed and the system speed (for which it was being THS-trimmed). i.e. It was unlikely that they actually hit Mach Crit and pitched up because of Mach Tuck. Thus the pitch-up may have been trim-induced and not pilot-initiated. Who's to know at this stage? But what happened next (the ballistic stall entry with 13 degrees nose-up THS) surely sealed their fate. The PF was never aware of that 13 degs nose-up THS (or he may have manually trimmed it out - yet another*completely*unnatural input action for a FBW Airbus pilot).
*
f. Ultimately, what killed their chances of recovery? It's very ironic that it was likely one of the systems meant to have saved them.
i.e. The BEA Report says: "At 2 h 12 min 02, the PF said "I don’t have any more indications", and the PNF said "we have no valid indications". At that moment, the thrust levers were in the IDLE detent and the engines’ N1’s were at 55%. Around fifteen seconds later, the PF made pitch-down inputs. In the following moments, the angle of attack decreased, the speeds became valid again and the stall warning sounded again."

At the sound of the stall warning, the pilot was likely deterred from any further initiatives (even though he was on the right track with his pitch-down inputs) - and he promptly then handed over the controls to his more senior PNF. A stall warning that sounds off as you exit a deep-stall condition? Not a great idea at all....... it is likely to have the opposite of the desired effect. The overwrought pilot might easily assume that his action is initiating a stall. A Doppler-based stall warning whose pitch and volume varies (dependent upon how embedded in the stall you are) would be a much safer (and saner) proposition.

It gets back to that old saw: "For the want of a nail...." Unfortunately for AF447 it was more than just a nail. It was a whole row of rivets that allowed the operation to become unglued.

So if you place a pilot in harm's way beyond his training and experience, fail a vital sub-system that then causes a failure cascade, can you really blame him for the outcome? Perhaps you should be blaming a system that's too lazy or incompetent to extrapolate failure modes into real world scenarios and identify real threats. The hazard was all too evident from all the prior Air France, Air Caribbes, NWA and other incidents (including QANTAS). Nobody acted with sufficient urgency to address the hazards. Hubris? In large measure I'd say.
*
PS Also see the attached file - revelations from a*DER Spiegel article

Mimpe
1st Jun 2011, 06:49
Somebody reaasure me please that there wasnt some automated voice screaming in the PF's ear saying " pull - up, pull - up" when his AoA was 40 degrees or whatever it was....with a 10,000 fpm ROD.

I shudder at the bit where the poor sods finally decide to push the nose down, only to have the stall warning reactivate........

ST27
1st Jun 2011, 06:50
I read NOT that they climbed, but they ascended, or, they were pushed, or, caught a severe updraft, and then wound up at 38,000 in a nose up condition, at below 60kts and thus literally out of control because at that time the controls would be inneffective.As a previous post notes, the BEA report says that the PF pulled the stick back, resulting in the climb. It was not an updraft. Given the time the nose up command was applied, it was likely deliberate, meaning the PF wanted to pull the nose up. That does not necessarily mean he wanted to climb, but perhaps that he wanted to bleed off speed, or perhaps for some reason thought they were in a dive, and needed to pull the nose up.

The report is not that clear about how much time the pull-up lasted, nor how much time the PF later spent trying to push the nose back down again, so it is also possible that when the AP dropped out, the nose rose on its own, and the PF was trying to counteract that tendency, and was pushing down. I would have thought that the report would have mentioned that sequence of events if it happened that way, since it would have been readily seen on the DFDR. However, the report is very thin, so much could have been left out.

Will have to see the final report to see what might have given the pilot the impression he needed to pull the nose up, or if he was reacting to the effects of the AP dropout. That would also explain his mindset, and perhaps help explain why he didn't later put the nose down to recover, other than for a few short attempts.

The fact that the aircraft lost as much speed as they did also supports the fact that the the climb was due to a nose-up command, since it takes energy to climb, and if an updraft provided the energy, they wouldn't have lost as much speed as they did in the process.

Note that the aircraft didn't drop as low as 60 kts in the climb. That was an erroneous speed displayed in front of the pilot, and recorded on the DFDR, presumably as a result of the blocked pitot tubes. The report suggests that the aircraft's actual speed only dropped to about 185 kts, which is what two separate speed indicators said when they came back into correspondence, meaning the blockage in the pitots had likely cleared again at that point.

fgrieu
1st Jun 2011, 06:53
From 38 000 ft down to 0, the trim/THS was at 13° nose up.
Starting around 2 h 12 min 17, still well above 10000 ft, there was an apparent attempt to get out of stall: nose down stick with engines around 55% N1. It did not work out. I'm trying to understand how the position of the THS is related to that failure.

Questions:
- Can it be determined what the flight law was during that nose down input?
- Is this mode consistent with the THS remaining static?
- Does this mode allow full deflection of the elevator?
- Was getting out of stall feasible despite the position of the THS?
- Do procedures to get out of stall, as (I guess) practiced in simulator, include manual action on the trim to get the THS back to neutral or nose down (or on the contrary is it customary to assume autotrim will take care of the THS)?
- Do these standard procedures include extending flaps to some degree, which is not mentioned in the BEA report?

Full disclosure: I'm not a pilot; I'm an engineer working on systems where security (not safety) is critical, and I like to understand by myself how failures happen.

jungle drums
1st Jun 2011, 06:56
Could it be that the pull up by the PF was purely to follow his flight director cues that were demanding a pitch up due to an overspeed condition as well?

Could the FD have been commanding a pull up caused by the aircraft sensing an overspeed condition that arose either by the rapid increase of mach no. from hitting the relatively hot air in the top of or leading the top of a very active itcz night time thunderstorm, and/or positive local thunderstorm wind vectors?

I know of two jet aircraft that have lost control in the tops of tropical TS due to being put outside the envelope suddenly in warm TS air at altitude.

And by the way - great post Hundredpercentplease at #1179 - hats off!!

Mimpe
1st Jun 2011, 07:29
'"The Shadow" - thanks. Thats a good effort and summary of the sad event.

opherben
1st Jun 2011, 08:36
HundredPercentPlease wrote:
"I too shall declare my interest: A320 Captain.

I really don't know where to start with this thread. So much noise, so little signal. The number of red herrings and long irrelevant side tracks is so great that no one can even start to address them.

The PF quickly and correctly diagnosed the situation. Loss of airspeed indication, resulting in AP/AT off and Alternate Law. He then incorrectly pitched up to 10° until the AoA was just 2° from the stall.

In this perilous position, the AoA increased again to 6° and the aircraft stalled. The response was incorrect with TOGA + pitch up.

So, two apparent errors. So much has been said about the wrong procedure being used (TOGA + pitch up is used in many other procedures) and a lack of training that I won't bother. But here is something frightening:

Most older Airbus pilots have done their time in cranky old jets and turboprops, where you fly by pitch. Everything is done by pitch settings - choosing, setting, adjusting, waiting and so on. However, in the world of the safety committee it is fine to pluck young lads straight from a Seneca and place them into an Airbus. To mitigate the risk, the flight director must be on at all times. Now all the cadet has to do is put the square in the centre of the cross. Never has a pitch been noticed nor noted.

I asked 5 first officers in the cruise to look me in the eye and tell me what pitch we were at (2.5°). 4 cadets answered between 5° and 10° http://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/icon25.gif, and one ex TP guy answered correctly at 3°. Not much of a sample, but indicative I suspect.

The Airbus is a fine aircraft. It is conventional, and simple. On top is a thick layer of cotton wool, that should protect us from our silly mistakes.

Once the cotton wool is removed, we are back into a simple jet. The snag is that with the current drive to train/recruit people as quickly and cheaply as possible, not one of the recent arrivals has ever flown in "simple jet mode" (by pitch and thrust). Incredibly in our airline it is now even prohibited to take off with the flight directors off.

I feel sorry for the two FOs on the flight deck. Without the FD they will have been in new territory. Without the airspeed, it is no time to have to guess pitch settings and develop a strategy to keep the thing in the air.

I hope the airlines have a good think about this. I imagine the safety departments will, but nothing will happen due to the cost of recruiting people with experience on conventional types.

PS: Below 60 knots I imagine the stall warning is inhibited because there is not enough airflow over the AoA vane to make it accurate and trustworthy.

PPS: Has any Airbus pilot here ever actually heard the stall warning in the sim? "

My interest: 36 years flying militarily and commercially, 90 aircraft types as PIC, expertise in flight instruction, experimental flight test and more. Management degree in air transportation.
You are essentially right on the money! I do however think that the layer of cotton shouldn't be there at all, assuming the pilot in command is qualified, by my standards. FD is an aid only at pilot discretion, pencil pushers should be kept out of such decisions. From what I read here and other threads, and my study of NTSB accident reports, it is risky to fly as passenger nowadays, without a solution in the horizon. Until people like us both with our qualifications make the call on how to run an airline.

jcjeant
1st Jun 2011, 09:09
Hi,

In most of the reports of accidents involving Airbus aircraft there is a constant:
Whenever it appears that some actions of either system (resulting themselves by actions of the pilot) have not been seen or understood by the pilot
It also appears that some informations (which could be very useful to the pilot) concerning malfunctioning or status of certain commands or automation are not show evidently to the pilot
This does not mean that Airbus is not a good aircraft (other reports about other planes were also reveals flaws) .. but he is cautious about this to become a constant

SoaringTheSkies
1st Jun 2011, 09:20
TheShadow

from what I can judge, you seem to have a fairly consistent story there. :D
If, and it's of course all still speculation, but if you're right, then there's a number of things to be addressed in the aftermath.

It seems that automation, albeit no doubt helpful and safe in most cases, was a factor here, or rather: the way the automation behaves when pushed outside the anticipated envelope (Stall warning silenced / reappearing)

Another factor is the question what parameters are available to the pilots in those extreme situations. I wonder what the rationale is not to have an AoA display, even in situations when the AoA is clearly way out of the normal. (btw, how many AoA vanes are there on a 330? I know I've seen three on Boeing types)

Training of extreme situations is yet another area that will have to be revisited. Have airlines become overly confident that automation will keep the plane inside it's operatinal envelope at all times? After all, the most important function of the guys and gals up front is to save the day in the (unlikely) event of the automation "losing situational awareness" and handing the whole mess over to the humans.

Lastly, I still think that Airbus might have gone too far in removing tactile clues such as coupled movement of the side sticks (how does the PNF know what the PF is doing on the stick in extreme situations like this?) and, albeit not relevant in this case, tactile feedback on the thrust levers. Eyes and ears are limited bandwidth channels and to forego the additional, very direct, tactile channel does seem to be a less than smart engineering decision.

[edit]
so I just found that the A330 has three AoA vanes just as any other self respecting jet. Makes me wonder even more why it's not displayed everywhere since traditional logic would say "one for the CPT, one for the FO and one for the backup instruments". Oh well.

edmundronald
1st Jun 2011, 09:35
Everyone here agrees the pitots were flawed.
Everyone agrees AF process was flawed in not enforcing substitution.
Everyone here agrees the Airbus automation is flawed in the way it handles bad sensor input.
No one here will admit that the pilot training may be deficient too.

Corporate myopia?

SoaringTheSkies
1st Jun 2011, 09:41
edmundronald

I beg to differ. Every single one of the statements you made there seems wrong.

Razoray
1st Jun 2011, 09:48
Aviate, navigate, communicate. They hadn't got past the first which is why you see no discussion of the third.

Mountain Bear,

Thanks...makes sense.:ok:

A37575
1st Jun 2011, 09:53
FD is an aid only at pilot discretion,

Agree. But I would guess that 99 percent of airline pilots - especially cadets - are lost without the crutch of a flight director. The training departments (simulator instructors) are at fault because they fail to understand that pilots should be taught that stick and rudder stills are the most important priorities in a pilot and the automatic goodies need to seen as aids - not the be all and end all of flying. As a simulator instructor I cannot ignore what I see and that is if the FD is deliberately switched off as part of hands on training, the usual result is significant out of tolerance instrument flying by the pilot.

SaturnV
1st Jun 2011, 10:57
Delta T, the Lufthansa at 350 that preceded AF447 by 20 minutes on UN873 deviated 10 NM to the west. The Iberia following AF447 by 12 minutes was at 370 and deviated by 30 NM to the east. AF459 (an A330-203) following the Iberia by 25 minutes deviated first by 20 NM to the west, and then 70 to 80 NM to the east of the track, and was given permission to climb to 370. Neither the Lufthansa or Iberia deviations would have significantly affected fuel consumption.

AF459 at the time of its deviation would have been unaware that various centers were trying to contact AF447. (DAKAR contacted AF459 at 0411 asking it to try and contact AF447.)

testpanel
1st Jun 2011, 11:02
:D:D:D for opherben!

Razoray
1st Jun 2011, 11:43
From what I read here and other threads, and my study of NTSB accident reports, it is risky to fly as passenger nowadays, without a solution in the horizon. Until people like us both with our qualifications make the call on how to run an airline.

Statistically speaking it is no more risky to fly nowadays as it was 20 yrs ago. In fact it is probably safer now.

Having said that....
I agree 100% that people with your experience, should be a voice in the aviation industry. The issue I see is a over-reliance on the "cotton". Automation and pilots must find the "comfortable" interface that advance the industry to even higher safety records. If you and your colleagues can help....than you should.

Capn Bloggs
1st Jun 2011, 11:54
No one here will admit that the pilot training may be deficient too.
If you read the post directly above yours, you will find:

Training of extreme situations is yet another area that will have to be revisited.
And there are plenty of other negative comments about training through this or the other thread IIRC.

Lemain
1st Jun 2011, 12:06
opherben -- We are getting to the stage where electronic instrumentation and control will be more reliable than humans. We are not there yet...too many things that can go wrong. Mechanicals, electricals, electronics, passengers(!) and GPS which is only available to us at Uncle Sam's pleasure. It will happen in time even if none of us reading this are alive to see it happen. So might we not expect this to be introduced by evolution while de-skilling pilots?

Yaw String
1st Jun 2011, 12:15
Regarding other traffic on the Atlantic that night, I wonder how much useful weather info was being passed on 123.45, by the earlier flights, in order to help fellow crews, on the same route as AF447. Many years of Atlantic crossings taught me that AF and LH seem to be the two airlines hesitant at giving, or receiving such info,or at least, they never replied!!!
We need to look after each other in this industry with all the pitfalls!...Monitoring Data and 121.5 does use up spare radios however!

iwrbf
1st Jun 2011, 13:00
Hi there,

german news outlet "Der Spiegel" has an interesting story about a german aerospace engineer (Professor, that is...) who experienced some strange (disturbing) behaviour in the simulator. Read yourself (english version):

Air France*Catastrophe: Victims' Families Propose Grounding All*A330s - SPIEGEL ONLINE - News - International (http://www.spiegel.de/international/world/0,1518,766148,00.html)

JamesT73J
1st Jun 2011, 13:00
According to flight global, automatic stab trim should have been inhibited when alpha > 30 degrees - Stalled AF447 did not switch to abnormal attitude law (http://www.flightglobal.com/articles/2011/06/01/357394/stalled-af447-did-not-switch-to-abnormal-attitude-law.html) but it was not.

So is this saying that the flight control system continued to do what was asked of it - trim for attitude / 1g and therefore trimmed in the stall - when it should have dropped out?


Edit: Isn't 30 degrees AOA..rather high?

grimmrad
1st Jun 2011, 13:24
As per the SPIEGEL article the relatives are basically demanding from a french judge to ground all A 330 and 340 worldwide until software issues regarding the trim of the elevator are resolved and to prevent further accidents.

As a SLF I find that somewhat mind boggling. I never had issues flying with the Airbusses but I am getting a bit more skeptical... I would like to know if any of the major carriers (BA, AF, LH, KLM, USAir, UA Delta) are analyzing the issue at hand...?

Dimitris
1st Jun 2011, 13:44
Guys maybe a stupid question:

How does the computer know that airspeed is less than 60knots so as to sound off the stall alarm if the airspeed is unreliable?

What if the plane is stalled at 80knots airspeed and the airspeed is unreliable 'showing' 50 knots. Will the stall alarm sound off?

AoA sensor is a small flap exposed in the airstream, how does the output of it in the cockpit (stall sound) is conected to an airspeed instrument that can be unreliable?

Can anybody expalin why AoA is not available under 60knots? If for some reason speed (reliable or not) is less than 60knots then there is no AoA input for the computers?

I'm obviously not a pilot, but I haven't understood the AoA unavailability under 60knots.

jcjeant
1st Jun 2011, 13:59
Hi,

Can anybody expalin why AoA is not available under 60knots?

Cause Airbus decided it will not be available cause their planes never go (in air) at this slow speed ............

aguadalte
1st Jun 2011, 14:25
I loved your post, "The Shadow". I agree with you.
As I have wrote a number of pages back, there are a number of questions waiting to be answered:

- What kind of information was being "shown" on Pilot Flying's #2 PFD/ND (yes I know it is not registered but, are there any conversation clues(?), other than the ones selected by the BEA to be transcripted to the report). Was he first responding to an overspeed indication,(2h10m16s) and only after he has reached 37500ft, (2h10m51s) he has triggered TO/GA in response to another "Stall, Stall" warning?
- What was the role played by the 13º Trimmable Horizontal Stabilizer (THS) plus the 4.9Ton of fuel stuck on the Trim Tank?
- What was the role of the "systems invalidations" design that below 60kts and 30kts, cancelled the "Stall, Stall" Automatic Call-Out Warning, and may have lead the pilots think they were out of it during precious seconds?
- We know that the Captain was able to reach the cockpit. It seems that by that time the speed read-outs were so low that the Stall Warning was out...but, what was his assumption of what was going on? By then, the aircraft was at about 35000ft, Pitch at about 15º and thrust 100%. Did he tell anything? Did he try to help? Didn't he notice the high pitch? Didn't he notice, the wings bouncing and the PF saying (only a minute after his entrance in the cockpit), that they were reaching FL100?
- Was the PNF so occupied, handling the ECAM, that he didn't notice the vertical speed rate, until FL100 was called off?Why did BEA apparently decided to disclose, only a part of the information?

Graybeard
1st Jun 2011, 14:30
Go outside, farmer, and look at the weather vane on your barn. Note, it aligns into the wind because its tail has more area than its point, which is only needed for static nose/tail balance. Note that it also has a lightning rod above it.

Angle of Attack is vertical measure of relative wind. The AOA sensor is just a high priced vertical weathervane, as seen previously on this thread. It's high priced because it has to be reliable in all imaginable weather and flight conditions, including direct lightning strikes or sweeps. It has some inertia and frictional damping to prevent flutter in all possible conditions.

Therefore, just as your barn's weathervane can be erroneious below about 10 knots wind, the AOA sensor cannot be trusted below about 60 knots.

You got a better AOA sensor? If not, why are you criticizing lack of Stall Warning below 60 knots?

If you don't understand this, maybe your time would be better spent shoveling out the barn.

ankh
1st Jun 2011, 14:32
&quot;a precise speed is critical. Just 15 kilometers per hour (9.3 mph) faster or slower and the plane can stall....&quot; Doomed Flight AF 447: Questions Raised about Airbus Automated Control System - SPIEGEL ONLINE - News - International (http://www.spiegel.de/international/world/0,1518,765764,00.html) Question -- at the top of a big storm cell, in that kind of turbulence, isn't the air around the aircraft changing direction faster than plus or minus 15 kph rapidly? what is the aircraft/pilot/computer detecting?

jcjeant
1st Jun 2011, 15:00
Hi,

In Bussiness Week ....

Air France Crew May Have Faced Baffling Data in 2009 Crash - Businessweek (http://www.businessweek.com/news/2011-05-28/air-france-crew-may-have-faced-baffling-data-in-2009-crash.html)

"The data and cockpit voice recording suggest the pilots never realized that the plane had stalled, BEA Chief Investigator Alain Bouillard said in an interview.

“They hear the stall alarm but show no signs of having recognized it,” he said. “At no point is the word ‘stall’ ever mentioned.”"