AF447 wreckage found

[nitpicker330]

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]

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.

[nitpicker330]

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]

@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]

@ 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):
"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]

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]

@nitpicker330 re response to stall alarm

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]

Psychologists have established that when human beings get "max outed" the first sensory input their brains delete is that of hearing.

[DouglasFlyer]

@aeromech3

No - the only warnings you get are:

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

[nitpicker330]

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]

Code:

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]

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]

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]

@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]

Hi,

Maybe old but a shool case:
http://www.fss.aero/accident-reports...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]

Aston........Yes it's ok to look up for fun value where time permits.

[Lemain]

Code:

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]

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]

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]

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......