PDA

View Full Version : AF447 wreckage found


Pages : 1 2 3 [4] 5 6 7 8 9 10 11 12 13 14

Graybeard
28th May 2011, 20:17
The maddening part of Birgenair is the Capt merely had to reach forward to his outboard instrument panel and rotate his Air DATA switch from NORM to ALT.

AeroPeru 603 was a through flight from KMIA to Chile. The arriving 727 was grounded for maintenance upon arrival Lima, so they hurriedly pressed the 757 into service. I don't know if it was a dedicated 757 crew, or a crew who normally flew both and was expecting to continue with the 727.

This accident is pretty well covered on wiki. I don't know how many line pilots would have been successful in the same circumstances, but the problem was surely more challenging than AF447.

Flight Safety
28th May 2011, 20:24
This is interesting, sorry if posted already:

Revised stall procedures centre on angle-of-attack not power (http://www.flightglobal.com/articles/2011/05/28/357321/revised-stall-procedures-centre-on-angle-of-attack-not.html)

Very relevant indeed.

thcrozier
28th May 2011, 20:55
Let's not use the term "deep stall" in reference to this accident. A "deep stall" is a specific kind of stall where the attitude of the aircraft is such that the wings block airflow to the horizontal stabilizer, making elevator inputs useless for recovery. Almost always involves a "T"-tail design, which does include any Airbus aircraft.Agreed. "Deep Stall" has developed a second usage in the media, where it seems to mean a rapid breaking stall from a high pitch attitude. I've even caught myself using it that way from time to time. :(

pattern_is_full
28th May 2011, 21:22
I noticed a mistake in my original that you quote - a critical missing "NOT"!

The real key to this accident will be to figure out why the PF thought holding full back stick all the way down was the correct response. I don't jump to a conclusion that it was simply "error." I'd like to see as good a re-creation as possible, from the data, of what the cockpit environment was actually telling the crew (alarms, instruments, ECAM messages, seat-of-the-pants, etc.).

Two of the clues that normally identify a stall would have been missing (airspeed) or perhaps disguised (buffet in the middle of convective turbulence - the pilots clearly were expecting buffets from turbulence, having changed course and warned the cabin). Pitch on the AH is not a trustworthy indicator of AoA (one can be 20° nose-down and still stalled with a 35° AoA).

I can't conceive of holding full back stick for 4 minutes in any aircraft. But I also can't conceive of any other trained pilot doing it unless some outside influence was suggesting such a bad idea was really a "good" idea. So "why"?

JJFFC
28th May 2011, 21:42
@ Flight Safety:ok:

Thank you for your 20:24

Your link :

"A formal document detailing the rationale for the revision points out: "There have been numerous situations where flight crews did not prioritise [nose-down pitch control] and instead prioritised power and maintaining altitude."
Operational experience has shown that fixating on altitude, rather than the crucial angle of attack, can result in an aircraft stalling."

Try the test : a pilot that doesn't nose down immediately when earing a stall warning has not understood what is a stall : the plane is no longer a plane, it is a cucumber.

If you don't nose down, you are dead within a minute or two.

The trouble is that :

" The statistical data shows that, when confronted by a stall, in 80% of cases, pilots pull back the control column, in a sort of reflex movement, which continues the loss of control.
The aircraft was subjected to a series of four full and rapid rolls. The first was attributed to the force brought to bear by the pilot on the left part of the control column; the following ones were due to pilot overcompensation on the roll then the stall. Having pulled the control column fully back and thus caused maximum nose up pitch, the pilot rectified this by pushing the control column fully forward. The aircraft dipped, with its nose going under the horizon by 32°. The roll-off from +50 to –32° in seven seconds was remarkable."
REPORT on the incident on 24 September 1994 during approach to Orly (94) to the Airb

ChristiaanJ
28th May 2011, 21:43
"Deep Stall" has developed a second usage in the media.The same has unfortunately happened with "FBW".

"Fly-By-Wire", as such, simply denotes using "electrical signalling" (the old-fashioned British term), i.e., using an electrical connection between the pilot's controls and the hydraulic servo-control units that move the flying control surfaces, instead of cables and rods.

Since.... it has become a synonym for hooking up all kind of digital electronic systems between the pilot's controls and the flying control surfaces, leading to the "now why is it doing that !!??" syndrome, and the mistrust, expressed here time and time again, of digital systems and software in general.

The real issue with "FBW" here seems to be with the digital part of the system... in which case reference to the "DAFS" (Digital Air Flight System) would be more appropriate... but I agree, the term "FBW" has now unfortunately become part of the vocabulary.

Concorde used FBW, in the real sense, but all of the rest of the AFCS (AP, A/S, A/THR, A/TRIM, SFC, etc.) was purely analog.
And FBW worked fine all the time... there was a mechanical back-up, which basically was never called on in service.

Ask21
28th May 2011, 21:57
I understand if that a stall is not dealt with properly immediately - or incorrectly - it may develop into a unrecoverable stall.

At what stall-angle (angle of atack) will the elevator be virtually useless to lower the nose? 30 og 40degrees?

Will it be possible to recover from 40 AoA stall using alternative methods? (asuming the elevator is not able to get the nose down) Indtroduce rotation /spin /wing-drop using rudder or ailron or single-side engine power.

Also - At high altitude - why would anyone use engine force to recover from a complete stall - concerning the potential disastrous delay it introduces to lowering the nose and AoA.

And would it be a idea to introduce an obligatory "stall recovery parachute" - it would perhaps be the only option to safely get a severely stalled aircraft into back in business.

Are even large passenger planes tested for a severe stall in real life?

Flight Safety
28th May 2011, 22:35
It might be useful for some to look at this:

http://www.faa.gov/other_visit/aviation_industry/airline_operators/training/media/Appendix%203-E_HighAltOperations.ppt

The notes for slide 29 are very interesting.

JJFFC
28th May 2011, 22:56
@Flight Safety:ok:
p29:

An airplane wing can be stalled Any airspeed, any altitude, any attitude
Pilot Tip:
If the angle of attack is greater than the stall angle, the surface will stall. Attitude has no relationship to the aerodynamic stall. Even if the airplane is in a descent with what appears like ample airspeed - the surface can be stalled.
Understand the difference between:
“Approach” to stall recovery
Stall recovery
Dramatic difference in recovery technique
Know the Difference


p43
http://www.faa.gov/other_visit/aviat...Operations.ppt (http://www.faa.gov/other_visit/aviation_industry/airline_operators/training/media/Appendix%203-E_HighAltOperations.ppt)
High altitude - stalls


Low speed buffet mistaken for high speed buffet
Actual full “Stall Recovery”
Higher altitudes:



Available thrust is insufficient
Reduce the angle of attack
Trade altitude for airspeed.

Could all the pilots on Earth, read that.

glhcarl
28th May 2011, 23:07
Yes, while in alternate law (and with the AA over 40º, abnormal attitude law) auto-trim is disabled.

Then is this site in error, because it states auto trim is available in "alternate law"? The only time auto trim is not functioning is in "direct law".

Airbus Flight Control Laws (http://www.airbusdriver.net/airbus_fltlaws.htm)

costamaia
28th May 2011, 23:22
@wallybird 7

The taped static port occurred on the Peruvian 757. Unsure if they were aware of it during take-off.

They were not aware until after TO.
Aeroperu 603 Transcripcion Del Voice Recorder (Espanol) (http://www.avweb.com/other/peru603s.html)

Phoenix_X
29th May 2011, 00:12
I will begin with the A310-325 approaching CDG years ago.
Capturing G/P from above the plane overspeeded the flaps placard, obviously, THE SMART COMPUTER decided it is a go-around so throttles up, and nose-up trim!
The dummy in the L/H site pressed the yoke, and pressed the yoke and...
---> THE SMART COMPUTER trimmed further nose up, and trimmed...

What a load of nonsense.... The computer didn't decide to go-around, it reverted to LVL CHG as advertised. Nothing to do with landing or going around. The computer didn't trim; according to the incident report the A/C was trimmed by one of the yoke switches.

Don't blame Airbus computers for everything. They do not decide to go around, and they do not simply trim full nose up 'cause they feel like it.

Flight Safety
29th May 2011, 00:14
One item that continues to puzzle me the most about this accident is what trimmed the Horizontal Stabilizer from +3 to +13 in one minute. Who did that, or what system did that? It was a lethal move.

thermostat
29th May 2011, 00:16
Where have you been hiding? Did you not see the weather report? They did go through the worst part of the storm. Why did other aircraft divert up to 90 nm around the storm if not to avoid it.

wallybird7
29th May 2011, 00:28
Let me add to the confusion. No one seems to have an answer as to why the plane zoomed up to 38,000 feet. At that time also the report mentions that the auto-pilot also kicked off. Thus the plane was in Alternate Law which to me means the only control of the plane was pitch thru the electric trim, and roll via the side stick which controls the rudder.

Once the plane was in a deep stall at low speed I don't know if the plane would respond to any flight controls. (I also don't know what the stall characteristics of the plane are)

If any of that is the case, then the pilots were simply along for the ride.

glhcarl
29th May 2011, 00:54
Let me add to the confusion. No one seems to have an answer as to why the plane zoomed up to 38,000 feet. At that time also the report mentions that the auto-pilot also kicked off. Thus the plane was in Alternate Law which to me means the only control of the plane was pitch thru the electric trim, and roll via the side stick which controls the rudder.



Again I ask the question, is this site incorrect when it states that auto trim is still used for over speed protection in Alternate Law!


http://www.airbusdriver.net/airbus_fltlaws.htm (http://www.airbusdriver.net/airbus_fltlaws.htm)

BarbiesBoyfriend
29th May 2011, 00:56
These 'experienced' pilots could barely 'fly' without an autopilot.

They've demonstrated that by killing themselves and all of their pax.

How much of a wake up call do we need to hear before we 'wake up'?

philipat
29th May 2011, 01:01
Interesting discussion. Central to all of this was the failure of the Pitots, it seems. Excuse my ignorance but in the 21st century, why do we still have to rely on hollow metal tubes to feed critical systems? Isn't it possible to feed such information as air speed from GPS or other more sophisticted satellite systems?

captplaystation
29th May 2011, 01:05
BarbiesBoyfriend,

Ken, I hear what you are saying, but. . . . do you think it was that they couldn't fly their aircraft, or that Airbus made it inordinately difficult (if not indeed impossible )to do in their situation.

I am still not too sure if all of this should be heaped on the crew. Don't think the machine was blameless, or too helpful, here.

thermostat
29th May 2011, 01:28
A beautiful demo to prove the point. Thanks.

Di_Vosh
29th May 2011, 01:43
philipat

Short answer: No!

21st Century has got nothing to do with it. GPS will give you groundspeed only, and GPS isn't 100% reliable as you can't always get enough satellites to give you accurate information.

In any case, GPS wont give you the direction and speed of the air that you're moving in.

Pitot tubes are still the best way to get accurate airspeed information.

Dark Knight
29th May 2011, 01:54
Attitude
Airspeed
N1


Attitude
N1

philipat
29th May 2011, 01:56
@Di Vosh

Thanks, just wondering out loud really.

gums
29th May 2011, 02:10
I wish to correct a misconception or two concerning the so-called "deep stall"

As Newt told Ripley, " my parents told me there weren't any REAL monsters.... but there are."

So I pulled stuff from a pre-historic publication and posted on the technical thread concerning AF447. PLZ read this and think about it, especially the quote from a "golden arm" test pilot describing what it felt like.

http://www.pprune.org/tech-log/449639-af-447-search-resume-part2-39.html#post6432295

Second, many folks associate a "deep stall" with T-tail designs and airflow over the horizontal stab/elevators. As you can see from the Viper, this is not a requirement. The problem occurs with a combination of c.g. and AoA and low speed. I flew the VooDoo as a yute, and it had the T-tail and it had a problem as someone alluded to here. At a sufficient AoA, downwash over that T-tail caused ever-increasing nose up pitch - we called it 'pitch up". It could happen at all speeds. but we didn't enter a "deep stall", we flipped end over end and rolled and yawed. Quite a ride. Due to conventional static stability and c.g. it was possible to regain control even without using the drag chute. however, SOP was wait until IAS was below drag chute limits and deploy the sucker!! Saved thousands of feet, and you didn't have to be a clone of Chuck Yeager.

Lastly, FBW is a lot more than a simple command of the control surfaces via electrical signals from the flight controls and the hydraulics that are there to move the suckers. True, the Concorde was closer to that, but I'll guarantee that there were some filters and dynamic pressures used to limit deflection and the rate of deflection. Not to the extent of the Viper or the late Airbus designs, though.

I can see a case to be made that the AF jet climbed steeply, ran out of air molecules over the elevator/THS and stalled. With the THS at a full ( within a degree) nose up command, and with a c.g. aft of most jets, it could enter a "deep stall" just as we had in the Viper.

thermostat
29th May 2011, 02:19
Exnomad, in the 11 years that I flew the A320, never once did we practice in the simulator :

A. Dual engine failure
B. Airspeed failure
C. Landing using only the standby instruments
D. Ditching

The pilots are expected to fly these automated airplanes for 6 months, then perform perfectly in the sim with very little practice.
Airlines have been cutting down on sim time due to cost at a time when automated aircraft are far more complex.

I believe that one day (4 hours) of training in the sim then doing a check ride the next day is NOT enough to cover all the training required. I have always felt that simulators should be used for training, not checking. The government inspectors can sit in on the training to make sure it is proper but the check ride should be done in the aircraft on a normal pax flight with a normal crew. That way more time would be available for crew training since money is tight.
In the case of AF447, the crew should have avoided the ITCZ weather in the first place, therefore all the recovery techniques would have been unnecessary. It's much easier to avoid a problem than it is to correct it.

thermostat
29th May 2011, 02:31
Di Vosh, during the last 2 years of my flying career I carried a hand held portable GPS unit with me on all my flights, just in case. This was in response to the 757 crash out of the Puerto Plata DR one night due to loss of airspeed indication. Also the the crash out of Lima Peru with taped over static ports.
The GPS provided me with ground speed, course and true altitude (not pressure alt). That is all the pilot of a jet needs to stay alive when all hell breaks loose.
My advice to all pilots is, get and carry a hand held GPS unit and take it with you on all your flights. And use it, just in case. Also please do not fly into CB's, they can give you a headache.

thermostat
29th May 2011, 02:50
fboizard, I'll try to answer you. First of all, what good would it have done. No one on the ground could have helped them.
Second, They were just too busy hand flying and dealing with a multitude of warnings.

SEIFR
29th May 2011, 02:52
thermostat :ok:

My 150$ GPS has been in my flight bag for the past 6 years.
Will I have time to pull it out and get it working when I really need it ? maybe not.
But it makes feel better.

Di_Vosh
29th May 2011, 03:07
Thermostat

Point taken re: hand held GPS. But I'm assuming (foolish to assume?) that the A330 has an on-board GPS and would display groundspeed on the EHSI.

I fly a Dash8-300 (not new technology) and we have this feature.

DIVOSH!

maynardGkeynes
29th May 2011, 03:22
Reading the BEA report, there's no indication that the crew lost all instruments, simply all instruments dependent on the pitot-static system. Attitude, derived from a combination of rate and attitude gyros should still have been reliable. The key difficulty faced by the crew was that the standard practice of using pitch + power to maintain safe flight without air data didn't seem to be working and the problem is that it won't if the aircraft is already stalled. With the airbus' FBW [fly by wire] system and passive stick, the crew would have none of the force or buffet cues through the side-stick that might have told them this.

At the same time, if the attitude of the aircraft is nominal [normal], power is nominal, but vertical speed is indicating -10,000ft per minute, the most likely cause is that the airplane is stalled. Yes, the VS indications could have been bad also, but it's less likely to be wrong than airspeed (requires only static pressure) and the crew had already tried the standard response.<<

nitpicker330
29th May 2011, 03:53
Boy there is some crap in here!!

Now read my lips:- In Alternate Law the aircraft flies basically like normal BUT without most protections. It doesn't use pitch trim for pitch!!


ALTERNATE 1. You can barrel roll the beast
ALTERNATE 2. You can barrell roll AND loop the beast.
( I may have these two backwards!! )

I've tried my Garmin GPS in the cockpit of the 330 and the 777 and it takes along time to log on to the satellites and drops out easily. This is most likely due to the thick gold lined heated windows and all the RF interference in the cockpit.

Now I don't mean to be disrespectful of the deceased but there has been enough information from Airbus and Boeing concerning these type of events for these guys to have learned from the past and prepared themselves accordingly. They either didn't know how to revert to "basics" or they were just slack....( ie they weren't famiar with their QRH )

Molokai
29th May 2011, 04:13
Well, the three pilots are all dead and cannot defend themselves. What we have are mere recordings which all the anal retentive techies think are infallible data telling the whole story. Well the recordings might have been correct but from erroneous instrumentations! Next, we have to consider how the erroneous readings and data were presented in the cockpit at the time of the accident.

Then let's consider the effects of continuous training in the sim year after year factored in the f/os' reaction to the confusing data presented in the cockpit. You will find training mainly focussed on windshear recovery, CFIT recovery and even stall recovery which calls for minimum loss of altitude in the sim nowadays. Their lack of experience or lack of presence of mind when faced with the confusing situation somehow regressed them to the reactions when faced with windshear as per their sim training year after year.

bubbers44
29th May 2011, 04:13
I think by now we know the FO flying totally screwed up. Pulling the nose up in a stall is opposite of any other stall recovery procedure. You always lower the nose and add power. We learned that in the Cessna 150. It works for all Boeings also. Airbus came up with this concept that you could just pull back the control and the computer wouldn't let you stall. Well, what if the computer fails? It obviously failed this time and over 200 people died for no reason. When will Airbus give up on the automatic airplane and pilots can be stupid and still fly it approach. Maybe they need to hire qualified pilots and let the 250 hr wonders pay their dues and do something doing actually flying for a while before they get in the right seat.

maynardGkeynes
29th May 2011, 04:23
Among the many differences between flying a small airplane and a big airliner, especially one with the Airbus's "fly by wire" control system, is that in some circumstances the right response in an Airbus can be to raise the nose. Please don't mention a Cessna. Regardless, if they had lost all their instruments, and with no visible horizon, even an exceptionally well trained and experienced professional pilot would have lost situational awareness and would not have been able to discern the pitch attitude of the aircraft.

wafelbolletjes
29th May 2011, 05:51
Two words describe best the action of the pilots and in particular the captain who thought it a good idea to take a break in the middle of the worst area of weather: criminal negligence.

Mac the Knife
29th May 2011, 05:57
I think it must have been very confusing to rapidly transition from a quiet cockpit to one with multiple distracting flashing and aural alarms, simultaneous contradictory loud annunciations and inconsistent instrument readings.

In the face of all drummed-in belief in the peerless automations, to discard all these, go to Direct or Mechanical Law, zero the trim and fly a standard EPR, uncage and follow the standby Attitude Indicator & Altimeter and all this very quickly would demand a special kind of cool and experience.

maynardGkeynes
29th May 2011, 06:10
Mac, once they stalled, with no instrumentation or VH, this was for all practical purposes unrecoverable in an Airbus due to the FBW.

fireflybob
29th May 2011, 06:17
Mac, once they stalled, with no instrumentation or VH, this was for all practical purposes unrecoverable in an Airbus due to the FBW.

Please explain why you think this

wafelbolletjes
29th May 2011, 06:56
mac the knife,

Is this supposed to be some kind of defense?

These highly paid pilots are expected to be able to handle such situations with ease. Ok so wow, they had to fly in the middle of the night, over the ocean, it was no doubt cold outside and windy and perhaps the seats were so comfortable that they felt sleepy and staring out of a window for hours at blackness is boring. Oh and we must sympathize that flashing lights are just too damn distracting.

Hello? They are supposed to be professionals. If they can't do their duty because of the above factors then they have no place in a cockpit. If i pay 500 euros for a flight i damn well expect the pilots do be competent enough to handle whatever inconveniences or distractions that might occur during their duty. Over 200 lives were lost because it seems the pilots didn't know what to do once the autopilot stopped flying the plane.

Anyone with a little bit of training on simulators can fly an airbus using the autopilot for 99% of the flight including ILS landing. But these pilots are paid for when the **** hits the fan and for their expertise, skills and judgement in those rare situations when the plane doesn't just fly itself for you.

Given what we know thus far, i expect trials will find the pilots criminally negligent and there will be huge compensation for the families.

TheShadow
29th May 2011, 07:11
As some technical "niceties" about the auto-trim system starts to emerge, it's beginning to sound as if the vagaries of the auto-trim system in respect of Airbus Law Change philosophy were instrumental in the inability of the AF447 crew to recover from the type of stall that they'd entered. i.e. they may have been victims of the circumstances of their stall entry scenario. To explain:

a. During the zoom climb to FL380 (in Alternate Law) the auto-trim transitioned from 3 deg N/up to 13 degs n/up (near to, if not max nose-up THS trim for the type).

b. Upon entering the stall ballistically and starting its "deep"-stalled descent, the aircraft would have been (and remained) in Abnormal Law, with the auto-trim inop and the trimmable horizontal stabilizer (THS) therefore locked at 13 degs nose-up..... unless it was to be manually changed by the pilot (and we now know that it was not).

c. The engines were at TOGA at this stage, so we have the pitch-up effect of TOGA power plus the THS "stuck" (i.e. de-automated) at 13 degs nose up.... both tending to pitch-up and support a stall continuance..... no matter what the pilots did (unless they were to change the acft configuration somehow - aerodynamically or CofG wise).

d. Airline pilot exposure to stalling tends to concentrate upon the approach to the stall and recovery (i.e. avoidance) with minimum altitude loss. In that stock standard scenario, one of the primary and persistent preliminaries in the incipient stall experience is the airframe buffeting and stick-shaker progression. This is de rigeur in a standardised level 1kt/sec deceleration towards a level 1g stall and is the cue for the trainee to take recovery action. However, if one enters a stall ballistically at high altitude, will there be any buffeting? The AoA system will issue a stall warning but is this against a distracting background medley of other aural alarms? Stall recognition and realisation then becomes an obscurity of the first order.

So the question now becomes: "What would be required to un-stall this aircraft (now in Abnormal Law) if there is insufficient elevator authority at 13 degs nose-up THS to get the nose down (and thus air over and across the wings and tail), during a stall locked in at 40 degs AoA (as predicated by their entry config)?" One answer might be: "Idle the power" (and this was done soon after the captain re-entered the flight-deck, possibly because he'd just misinterpreted their predicament as a L.o.C., based upon a quick scan). Another might be: "Manually run the trim" (i.e. not something that comes naturally to an Airbus pilot - particularly not if he's unclued and quite unaware that the 13 deg nose-up THS is now his basic problem). A pilot's normal cueing to adjust trim is that the airplane is "out-of-trim" and tending to deviate from a chosen flight-path i.e. not a player in this deep-stall scenario.

Three questions: 1. "Will the pilot be aware that he's in abnormal Law? (and the portents of that)" The answer might well be: "Probably not" (there's nothing to promote awareness of this being the case i.e. no aural annunciation - and thus we arrive at: what now needs to be done that's essential for recovery?)
2. "Does the elevator alone have sufficient authority to unstall the wings at max power or at idle?" The answer is probably not, at least not while the superior trim authority of the THS at 13 degs n/up holds sway.... and particularly not whilst at TOGA power.
3. "Why doesn't the elevator have sufficient authority to unstall?" The whole design premise of the THS is to reduce trim drag and allow the elevator to become more of an active trim and less of a primary flight control. This ideation works well 99.99% of the time and it's used in all models of airliners to some degree. They need the capability of coping with large CofG ranges to accommodate loading, fuel burn-off and configuration changes. Some aircraft augment this capability with tail-located fuel trim-tanks. However this minimalistic elevator design feature in the A330 apparently won't "work" in the progression of events that AF447 underwent.

So are Airbus elevator throws and areas (i.e. authority) an under-design or does the THS have undue authority? That becomes the question here as we switch our attention to not blaming the pilots but agonizing over possible Airbus design deficiencies. But before we look into that, we need to pose the question: "Were the AF447 pilots aware that they were locked in an aerodynamic stall?" I'd suggest that they were NOT..... mainly because of the circumstances of their entry being wholly unfamiliar..... and that medley of aural alarms mentioned earlier that had overloaded their capacity to assimilate transient info. It's called cognitive disequilibrium, an idiosyncratic need to ignore or de-prioritize - a close relative of cognitive dissonance (a tendency to rigorously deny or disbelieve), two behavioral paradigms to which professional pilots are prone. One final thought, centering upon human factors. When the captain entered the cockpit and tried to take it all in at a glance one of the things he would've missed, because of its positioning, is what the pilot's input was on his sidestick. With a yoke (thinking of Egyptair MS990 here) it's visually apparent that what's afoot is directly related to pilot action. Food for thought.

Are there any precedents in the Airbus incident and accident annals? There's the Air New Zealand A320 test-flight crash and the Tarom Airbus near accident on ILS finals at CDG..... that spring to mind.

It's worth citing an extract from the Tarom incident: "Under the aerodynamic effect of this THS deflection (of 13 degs) and under the mechanical effect of thrust, the aircraft was thus subjected to a nose-up force that could not be controlled by elevators. It rapidly assumed an extreme pitch attitude and angle of attack.

There may be others. The 1994 crash on go-round of a (non-FBW) A300 at Nagoya? (link (http://www.rvs.uni-bielefeld.de/publications/Incidents/DOCS/ComAndRep/Nagoya/nagoya.html)). Para 4.2.b of this link (http://www.skybrary.aero/bookshelf/books/680.pdf) lists 6 Airbus incidents and one B747 involving pitch-trim anomalies. An extract from that Nagoya narrative might help emphasize the sometimes inordinate power of a THS in some circumstances: After the PF inadvertently pressed TOGA on finals,

"The autopilot automatically went into GA mode, and this would have shown on the primary flight display (a very vague alert really). The aircraft was flying 18 degrees nose-up, normal for a go-around, but the FO was pushing heavily on the yoke to get the nose down. He was meeting heavy resistance, a design indication on almost all airplanes that that his manual commands were in conflict with the autopilot. For nearly 20 seconds, as he applied down-elevator, the autopilot moved the trimmable horizontal stabilizer (THS) in the opposite direction to keep the nose up. At T+30, THS reached maximum nose-up; at T+42, the autopilots were disengaged. Pilot C asked for autothrottles engaged and took control, increasing down elevator to full deflection as the aircraft began climbing. Alpha-floor (an Airbus automatic protection mode) triggered at T+50 from excessive AOA. Alpha-floor triggered maximum thrust for climb-out, but that added thrust in fact increased the nose-up attitude to 52.6 degrees (one may surmise that the thrust centerline is below the rotational center of the airplane, and at low speed there is not much aerodynamic force to maintain resistance to this rotation). (52.6 degrees is very steep. A high-friction granite rock face of this angle would nevertheless be considered a technical rock climb.) C disengaged alpha-floor by retarding thrust and tried to get the nose down again with trim. Airspeed had dropped to 78 kt., the aircraft stalled at 1,800 ft, and control was not regained before it hit the ground."

If the BEA Inquiry into AF447 heads down this well-trammeled path towards THS excess authority and control law anomalies in stalls, Airbus is going to have to do the old quickstep that they've always done so well - in order to avoid changing physical design. No doubt it will take the form of a circuitous software patch to the control laws and/or yet another aural alarm and cautionary bulletin.
Edited to add:
However, despite all of the above, there is no denying that “no clear-cut stall recognition and persistent warning” is the apparent deficiency that put AF447 into the Atlantic. Recognizing that the overwhelmed pilot can become clueless in a time of great stress, perhaps aural alarms should become aural admonitions: as in “Stall Warning. Reduce angle-of-attack and trim nose-down for recovery”

ZBMAN
29th May 2011, 07:19
Two words describe best the action of the pilots and in particular the captain who thought it a good idea to take a break in the middle of the worst area of weather: criminal negligence.

Well I think it is criminally ignorant and stupid to post such a comment :mad:. Do come back later once you know what you are talking about. In the meantime stop wasting my time reading such crap.

wafelbolletjes
29th May 2011, 07:28
When the media, AF, the investigation and the courts start using those 2 words, i expect an apology ZBMAN.

Sampan Angkasa
29th May 2011, 07:28
Maybe they need to hire qualified pilots and let the 250 hr wonders pay their dues and do something doing actually flying for a while before they get in the right seat.

The more senior f/o had over 6600 hours of which 2600 are on type. Junior f/o had more than 3000 hours!

A newbie 250 hour wonder probably would have had better CRM, more recent and genned up on the flight control systems.

Rananim
29th May 2011, 07:34
Excellent analysis from The Shadow.Frightening though.I looked at this accident from the POV of a pilot of a real plane that does what you ask and never does things subtly without you knowing only to leave you unprotected at the worst moment possible.My mistake.So auto trim is not so cool after all.I wont comment further because it will be bad for my blood pressure.I see the pilot's predicament in a new light though after the Shadow's post and I think it is definitely mitigating.

wafelbolletjes
29th May 2011, 07:42
While TheShadow's points may be valid, they don't excuse the pilots for not even trying to point the plane's nose downwards (for the last 3 minutes). It also doesn't excuse the pilots for not realizing that the plane was in fact stalled. If it's going down at 10k fpm with nose up attitude and full throttle then, duh, it must be stalled.

If the pilots had however been pushing forward on the sidesticks and screaming about how the plane was stalled on the CVR then we can solely lay the blame on airbus design flaws. But that's not the case. I won't comment again because it is clear the pilots here will never lay the blame on fellow pilots. I'll no doubt be labelled an idiot but at least i am not an idiot responsible for the death of over 200 innocent adults and children.

fullforward
29th May 2011, 07:43
Fully agree with you.

WaffelPlease go back to your Flightsim and enjoy.The problem is this is an open forum and then we waste time reading loads of crap here.
It's tiring, boring to try to explain the basics to people like you, sorry.

BTW, congrats on the brilliant post "The Shadow"! You counterbalance at least ten of the b****ters.
Keep up the good job.

edga23
29th May 2011, 07:49
Will the pilot be aware that he's in abnormal Law? (and the portents of that)" The answer might well be:[COLOR=SlateGray][I] "Probably not" (there's nothing to promote awareness of this being the case i.e. no aural annunciation - and thus we arrive at: what now needs to be done that's essential for recovery?)

AH no??? The PF announces Alternate Law when he takes manual control of the aircraft. It is in one of the first lines in the BEA communication !!!

2. "Does the elevator alone have sufficient authority to unstall the wings at max power or at idle?" The answer is probably not, at least not while the superior trim authority of the THS at 13 degs n/up holds sway.... and particularly not whilst at TOGA power.

In ALT LAW with AP an AT off there is virtually no Stall protection left. The THS goes where the pilot wants it to go. It simply responded to the pitch-up inputs by the pilot to 'help' him go where he wants. Had he made pitch-down inputs afterwards it would simply have gone in the other way, although it would take a continuous pitch-down input for some time.

Heathrow Harry
29th May 2011, 07:55
anyone else feel that this post is totally pointless ???

Everyone posting their own take on the situation then using it to back their own particular hobby-horse (AB, Boeing, manual flying, anti-French, conspiracy theorists, etc etc ) and then slaggong off everyone else

really depressing TBH :bored::bored::bored:

abovethesky
29th May 2011, 07:59
To TheShadow:
Three questions: 1. "Will the pilot be aware that he's in abnormal Law? (and the portents of that)" The answer might well be: "Probably not" (there's nothing to promote awareness of this being the case i.e. no aural annunciation - and thus we arrive at: what now needs to be done that's essential for recovery?)
As the voice recorder proofs, they knew very well, see the report.
2. "Does the elevator alone have sufficient authority to unstall the wings at max power or at idle?" The answer is probably not, at least not while the superior trim authority of the THS at 13 degs n/up holds sway.... and particularly not whilst at TOGA power.
3. "Why doesn't the elevator have sufficient authority to unstall?" The whole design premise of the THS is to reduce trim drag and allow the elevator to become more of an active trim and less of a primary flight control. This ideation works well 99.99% of the time and it's used in all models of airliners to some degree. They need the capability of coping with large CofG ranges to accommodate loading, fuel burn-off and configuration changes. Some aircraft augment this capability with tail-located fuel trim-tanks. However this minimalistic elevator design feature in the A330 apparently won't "work" in the progression of events that AF447 underwent. The PF didn't try to use the elevator to unstall, their input was "nose up", see the report.

A much more realistic explanation is http://www.pprune.org/rumours-news/447730-af447-wreckage-found-38.html#post6479529.

ExSp33db1rd
29th May 2011, 08:05
Perhaps they reacted to windshear, rather than stall.

Full back stick and TOGA, then hold both until the aircraft flies out of the problem.

I think that this is an excellent comment.

I know I'll be told that one can't get the sort of low level windshear that demands such aggressive response at altitude, but once the mindset has been made, and all sorts of confusing information is being thrown at one, then I can see the scenario that occurred being played out.

I'm glad I wasn't there.

wafelbolletjes
29th May 2011, 08:05
I really wasn't going to reply again but... like a tickle...

fullforward, people like me? I have a Master in aerospace engineering and am working on my PhD (in the area of aerodynamics). I don't appreciate being labeled 'people like you'. I probably know more than you about stalls.

The fact is, and this is an indisputable FACT, the plane was fully functioning and the pilots crashed this plane into the ocean. Talking about auto-trim, psychological anomalies or design flaws are the conspiracy here, not me stating the obvious that the pilots didn't know how to fly the plane. Don't shoot the messenger.

IcePack
29th May 2011, 08:09
A good post shadow. Interesting in that on a few occasions in the little bus on a normal go around the a/c some times over pitches with the speed reducing below VLS Airbus then had to change some control protections to include a mod to the speed reversions. Having said that disconnecting the auto guidance & applying some fwd stick puts things back to normality. I have not had that problem with the big bus. However a pilot must realise that the automatics are not infalable just like pilots aren't either.

fireflybob
29th May 2011, 08:12
I have a Master in aerospace engineering and am working on my PhD (in the area of aerodynamics).

but, wafelbolletjes, with all respect, are you a pilot?

I probably know more than you about stalls.


That may, or may not, be true but that doesn't mean you would/could do any better than these pilots in the situation they found themselves.

Zorin_75
29th May 2011, 08:13
When the media, AF, the investigation and the courts start using those 2 words, i expect an apology ZBMAN.He won't owe you one. This isn't about you turning out to have been right or not. This is about you jumping to conclusions and condemning people without the knowledge and the facts to back it up.

abovethesky
29th May 2011, 08:17
but, wafelbolletjes, with all respect, are you a pilot? Please, refrain from ad hominem attacks, and focus on arguments instead.

Zorin_75
29th May 2011, 08:24
Will the pilot be aware that he's in abnormal Law? (and the portents of that)" The answer might well be: "Probably not" (there's nothing to promote awareness of this being the case i.e. no aural annunciation - and thus we arrive at: what now needs to be done that's essential for recovery?)AH no??? The PF announces Alternate Law when he takes manual control of the aircraft. It is in one of the first lines in the BEA communication !!!He's talking about Abnormal law, not Alternate law. The relevant difference here being autotrim not working in Abnormal law.

fireflybob
29th May 2011, 08:26
Please, refrain from ad hominem attacks, and focus on arguments instead.

abovethesky, it wasn't an attack, merely a request for information!

It is relevant to the matter under discussion. Whilst having every respect for those having technical qualifications far superior than a mere mortal pilot, such as I, unless you have done or are doing the job as a pilot you really have little appreciation of what these pilots were faced with.

There is too much condemnation going on here of the pilot's actions, especially when we don't know all the facts.

abovethesky
29th May 2011, 08:26
To TheShadow:
Your analysis is based on wrong assumptions:

Three questions: 1. "Will the pilot be aware that he's in abnormal Law? (and the portents of that)" The answer might well be: "Probably not" (there's nothing to promote awareness of this being the case i.e. no aural annunciation - and thus we arrive at: what now needs to be done that's essential for recovery?)
They know very well, see the repport.
2. "Does the elevator alone have sufficient authority to unstall the wings at max power or at idle?" The answer is probably not, at least not while the superior trim authority of the THS at 13 degs n/up holds sway.... and particularly not whilst at TOGA power.
3. "Why doesn't the elevator have sufficient authority to unstall?" The whole design premise of the THS is to reduce trim drag and allow the elevator to become more of an active trim and less of a primary flight control. This ideation works well 99.99% of the time and it's used in all models of airliners to some degree. They need the capability of coping with large CofG ranges to accommodate loading, fuel burn-off and configuration changes. Some aircraft augment this capability with tail-located fuel trim-tanks. However this minimalistic elevator design feature in the A330 apparently won't "work" in the progression of events that AF447 underwent. The PF didn't even try nose down. He wanted nose up. So all the speculation whether we would have been capable of bringing the nose down (elevator, trim) is mood.

The analysis of Flight Safty makes much more sense.

abovethesky
29th May 2011, 08:31
He's talking about Abnormal law, not Alternate law. The relevant difference here being autotrim not working in Abnormal law.
He obviously misspoke, because they were in Alternate law, not Abnormal law.

abovethesky
29th May 2011, 08:35
abovethesky, it wasn't an attack, merely a request for information!

It is relevant to the matter under discussion. Whilst having every respect for those having technical qualifications far superior than a mere mortal pilot, such as I, unless you have done or are doing the job as a pilot you really have little appreciation of what these pilots were faced with.

There is too much condemnation going on here of the pilot's actions, especially when we don't know all the facts. Nobody who isn't a pilot can imagine how it is in such a situation.

Nevertheless, it is a valid question why the PF didn't try to unstall by nose down, and this question is valid no matter who asks it.

See also the link provided by Flight Safty.

Zorin_75
29th May 2011, 08:39
He obviously misspoke, because they were in Alternate law, not Abnormal law.
That's the point, we don't know (yet) if at some point law switched to abnormal. Low airspeed and high AoA to trigger it were present in any case.

cyflyer
29th May 2011, 08:40
I found this CNN report interesting

CNN.com International - Breaking, World, Business, Sports, Entertainment and Video News (http://edition.cnn.com/video/#/video/bestoftv/2011/05/27/exp.nr.quest.air.france.explainer.cnn?iref=allsearch)

JCviggen
29th May 2011, 08:41
Nevertheless, it is a valid question why the PF didn't try to unstall by nose down, and this question is valid no matter who asks it.

Imo the most likely explanation is that they did not believe or realise they were actually stalled. Not until it was too late, anyway.

wafelbolletjes
29th May 2011, 08:43
face down *** up thats the way planes like to ****!

It's also how you recover from a stall.

abovethesky
29th May 2011, 08:46
Quote:
He obviously misspoke, because they were in Alternate law, not Abnormal law. That's the point, we don't know (yet) if at some point law switched to abnormal. Low airspeed and high AoA to trigger it were present in any case. Leaving aside wired conspiracy theories, we know very well. Abnormal law enables only in case of extreme attitude, which definitely wasn't the case.

nitpicker330
29th May 2011, 08:55
Gee and I thought this was the "Professional Pilots rumor network"

There is no "Abnormal" Law on the FBW Airbus. :ok:

Normal
Alternate 1
Alternate 2
Direct

Ok.

got it?

Good


Correction.........see below :ouch:

nitpicker330
29th May 2011, 09:02
Ok, Let me re-post the Quick Reference Handbook information on just what these guys faced. This info was available long before this accident. It may also help to explain to those that don't fly the Airbus.

The QRH spells the situation quite clearly:---

Unreliable speed indic/ADR check proc:-

Maybe due to Radome damage, air probe failure or obstruction
Indicated Alt may be effected if static probes effected
Unreliable airspeed cannot be detected by the ADIRU

Since Flight control laws maybe effected maneuver with care
Unreliable speed may be suspected by-
--- Speed discrepancies between ADR 1, 2, 3 and standby
---Fluctuating or unexpected increase/decrease/steady indicated speed or pressure altitude
---ABNORMAL CORRELATION OF THE BASIC FLIGHT PARAMETERS
---Abnormal AP/FD/ATHR behavior
---Stall warnings, or overspeed warning or flap relief warnings that contradicts with at least one of the indicated speeds
-RELY ON THE STALL WARNING THAT COULD BE TRIGGERED IN ALTERNATE OR DIRECT LAW. IT IS NOT EFFECTED BY UNRELIABLE AIRSPEEDS BECAUSE IT IS BASED ON AOA
-DEPENDING ON THE FAILURE, THE OVERSPEED WARNING MAY BE FALSE OR JUSTIFIED. BUFFET ASSOCIATED WITH THE OVERSPEED VFE WARNING IS A SYMPTOM OF A REAL OVERSPEED CONDITION.
---Inconsistencies between radio altitude and pressure altitude
---Reduction in aerodynamic noise with increasing airspeed or increase in aerodynamic noise with decreasing speed

*my capitals to emphasize some sections*

abovethesky
29th May 2011, 09:03
There is no "Abnormal" Law on the FBW Airbus.There is. But it happens only under a so exotic condition that it's usually not mentioned.

nitpicker330
29th May 2011, 09:07
Above the sky....... Yes I must apologize you are correct. I just looked at FCOM 1 and it applies during abnormal attitudes.......

I'll take my foot out of my mouth now :E

spornrad
29th May 2011, 09:11
1. This crew got killed in their frantic struggle with an erroneous system. There are flaws in the system that prevented them from correctly recognizing the situation.
Air France Pilots Were Probably Confused by Cockpit Instruments in Crash - Bloomberg (http://www.bloomberg.com/news/2011-05-27/air-france-crash-probe-shows-jet-stalled-plunged-3-1-2-minutes-to-ocean.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.”

2. The PF did try to pitch down. The system acknowledged this effort with a renewed stall warning. He did probably not try again.

Criminal neglect is to blame at this stage somebody who is not here anymore to explain his actions, instead of questioning the entire system including training.

Gary Brown
29th May 2011, 09:12
Let me bang on like a broken record about the very similar Air Caraibes A330-200 incidents (2 of them, handled successfully, the same way, in September of 2006):

http://www.eurocockpit.com/docs/ACA.pdf

In the case detailed, the "incident" lasted about 2 minutes, from initial unreliable airspeed disconnect to restoration of working FDs and APs.

During that time (and, to be fair, the way in which the a/c had been set up in the preceding few minutes to deal with icing and turbulence) the PF had time to:
a) safely and successfully fly the plane using "manually" set thrust and pitch;
b) consult the GPS Altitude and Groundspeed;
c) listen to the PNF going through the Unreliable Airspeed checklist (with a plethora of Stall, Overspeed and other warnings sounding);
d) decide that the Stall Warnings were inappropriate (and thus holding on to his thrust and pitch decisions);
e) notice that the Checklist contained contradictory advice regarding stall warnings.

So, what was different with AF447? Obviously, we do not know if the circumstances facing the crew were identical. And we do not know if they used the checklist. And we do not know if the checklist was identical. And we don't know why the crew took the decisions they did. But we do know that the Air Caraibes PF was quick enough to figure that almost nothing the a/c was telling him - airspeed, AoA, stalls, overspeeds, checklist advice - was going to help him keep his plane up.

Zorin_75
29th May 2011, 09:15
Gee and I thought this was the "Professional Pilots rumor network"

There is no "Abnormal" Law on the FBW Airbus. http://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/thumbs.gif
Sorry, not being a bus driver I was going from what I've been able to find on the net:

http://www.airbusdriver.net/airbus_fltlaws.htm:
ABNORMAL ALTERNATE LAW Abnormal Alternate Law is activated if the airplane enters an unusual attitude, allowing recovery from the unusual attitude.

Pitch law becomes Alternate (without autotrim or protection other than Load Factor protection).
Roll law becomes Direct law with mechanical yaw control.


Unfortunately it doesn't say what exactly constitutes an "unusual attitude" but I'd have considered > 40 deg AoA and < 60 knots airspeed as per the BEA report to be some factors that might go in that direction.
Maybe you could check the exact parameters for this?

kiwiandrew
29th May 2011, 09:22
I found the CNN story posted above interesting too, I never knew that AF had RR engines on their A330s, nor that AF routinely fly their aircraft with gear down in cruise. :ugh:

nitpicker330
29th May 2011, 09:22
Quote from FCOM 1

Abnormal law due to:
- Pitch attitude >50 deg nose up or 30 deg nose down
- Bank angle >125 deg
- AOA > 30 deg or < -10 deg
- Speed > 440 kt or <-60 kt
-Mach >.96 or < 0.1

The law in pitch is the Alt law without protections and without auto trim.
In Roll it's full authority direct law with Alt Yaw

After recovery they are:-
Pitch Alt law
Roll. direct law with yaw Alt law.
:ok:

cyflyer
29th May 2011, 09:28
I found the CNN story posted above interesting too, I never knew that AF had RR engines on their A330s, nor that AF routinely fly their aircraft with gear down in cruise


Never noticed about the RR engines Andrew, but as an illustrator to the events, for the average person watching, it was well presented I think.

edmundronald
29th May 2011, 09:33
Let me bang on like a broken record about the very similar Air Caraibes A330-200 incidents (2 of them, handled successfully, the same way, in September of 2006):

http://www.eurocockpit.com/docs/ACA.pdf

In the case detailed, the "incident" lasted about 2 minutes, from initial unreliable airspeed disconnect to restoration of working FDs and APs.

During that time (and, to be fair, the way in which the a/c had been set up in the preceding few minutes to deal with icing and turbulence) the PF had time to:
a) safely and successfully fly the plane using "manually" set thrust and pitch;


They did good. So maybe someone should learn something from the training they had. Although this forum is full of professional pilots saying that the AF crew were professional, people out there clearly expect a different standard.

JJFFC
29th May 2011, 09:33
"" The statistical data shows that, when confronted by a stall, in 80% of cases, pilots pull back the control column, in a sort of reflex movement, which continues the loss of control.
The aircraft was subjected to a series of four full and rapid rolls. The first was attributed to the force brought to bear by the pilot on the left part of the control column; the following ones were due to pilot overcompensation on the roll then the stall. Having pulled the control column fully back and thus caused maximum nose up pitch, the pilot rectified this by pushing the control column fully forward. The aircraft dipped, with its nose going under the horizon by 32°. The roll-off from +50 to –32° in seven seconds was remarkable."
REPORT on the incident on 24 September 1994 during approach to Orly (94) to the Airb"

WHEN YOU EAR A STALL WARNING = you are dead within a minute or two instead you nose down.

It seems that 80% of the crew have not this picture in mind = there plane is a stone.

The beginnig of the stall is the plane is rocketed to a high altitude then fall.

That's all folks.

This is the FIRST lesson of 100% of the instructors in the world.

80% of the crews don't follow their first lesson : it is this mental reaction that has to be fightened, not the plane.

Aldente
29th May 2011, 09:41
Just a thought, but assuming this was visible on the radar at the time the Captain left the flight deck, was this really a good time for him to take his in-flight rest period ?

Think I might have waited somehow ......


http://i52.tinypic.com/2927j8l.jpg

nitpicker330
29th May 2011, 09:43
Edmund......This is not new, before the Air Caraibis incident my Airline had a similar thing occur over the South China sea in an A330. They had their pitot probes ice up from super cooled water and they then had all the same things happen.
AP A/THR dropped out
Simultaneous overspeed AND under speed warnings
Alternate Law

Etc etc

They were initial hung out to dry but the union proved the Radar was at fault and the crew hadn't actually exceeded any limitations.

So, the Airline changed the Radars on all the 330's and changed the Pitot tubes to the newer model.

This is not a new thing..

beardy
29th May 2011, 10:26
For those not familiar with Airbus abnormal law:

An abnormal attitude law in pitch and roll is provided if the aircraft is in flight and in any of
these conditions :
– Pitch attitude > 50◦ nose up or 30◦ nose down
– Bank angle > 125 ◦
– Angle of attack > 30◦ or < - 10◦
– Speed > 440 kt or < 60 kt
– Mach > 0.96 or < 0.1
The law in pitch is the alternate law without protection (except load factor protection) and
without auto trim. In roll it is a full authority direct law with yaw alternate.
After recovery, the flight controls laws are:
in pitch : alternate law
in roll : direct law with yaw alternate law

So it could have been in abnormal law due to the airspeed indications. If this is the case then lack of elevator authority due to the THS position would probably have been self induced due to the stick back being held. However, once airspeed indications had been restored the aircraft would no longer have been in abnormal law and auto trim would (probably) have been restored along (eventually) with elevator authority.

nitpicker330
29th May 2011, 10:32
With other A330 similar incidents after exiting the area and the probes de-iced most Control Laws returned to normal. ( With one they had a Prim fault that they couldn't reset I think ). All flights landed normally with only a few injuries from the Turbulence ( WX ) encounter.

fullforward
29th May 2011, 10:37
The more I read, the more clear it gets: the poor guys failed to recognize they were flying a full stalled plane, got absolutely scared by the bells and whistles blaring all the time, rocking wings, winding down altimeters, a panicked captain shouting instructions and simply frozen at the controls (or even worse, giving inputs that agravated the situation), failing to do the only thing that would have saved the day.
Pure lack of proper training, basic airmanship & situation awareness.
It's hard to admit that a lot of us could have reacted exactly the same way.:{

A perfectly flyable aircraft turned into a gigantic coffin.

Of course there'll be endless theories about A330 systems, speculations on Boeing x Airbus, if this, if that etc...

Jetjock330
29th May 2011, 10:42
Has anyone considered the 5000kg's of fuel in the trim tank in cruise has an influence on the stall with regard to C of G?
Most of the times we practice stall recovery (in alternate law) in the sim, as per the new requirement, the stalling is done at a lower level than when aft trim fuel has taken place (FL255). I have not tried it with 5000kg in the trim tank at 38000ft yet. I reckon it is definitely not a pleasant outcome, however, we are all trained to avoid this and fly pitch angle and power setting.

Ask21
29th May 2011, 10:43
OK- I'm not a professional pilot - but I did my first stall/spin recovery from 3000 feet at age 14 in an sailplane training and solo flying( a long time ago) - so thats my background.

One of the most interesting issues here is what options the captain had when he arrived in cocpit - assuming he recognized the stalled configuation. Assuming the AoA allready in the +40 degrees area and 10000 feet/min sink-rate.
13deg trim obviously led to the disaster - but at 40 deg AoA on wings - would not the horisontal stabilizeer/elevator allready be fully stalled incapable of producing a tail-lifting force at all. At some point of stall development pitch authority will be lost - isn't it so

With a pitch +15 degrees - level wings . and Center of Gravity in the aft region - and since theres no stall recovery parachute installed - What are the options?
Triming down the elevator is obvious - but it would increase the AoA of the horisontal stabilizor increasing the stall of that surface

Exteding landing gears would be one option - to produce a nose-lowering force.
I suggest also a mild reverse trust on engine might be one of very few options available.

After all - what you would like to have is a pitch up stall converted to a steep - steep dive 70-80 degrees- where the forces of gravitation actually will work for you - not against you. In a steep dive with the nose directly towards the ground the Airplane will be flyable again.

So the most realistic option would perhaps be to "drop a wing" - using rudder or aileron if aileron autority still exist - and then use rudder to convert a high bank angle to a steep vertical dive - thereby enabling oneself to fly again

awqward
29th May 2011, 10:43
My first thoughts on reading the report were: why did the Captain leave the flight deck given the weather that must have been painted...even if he remained in the jump seat...as it was he returned to a chaotic cockpit, trying to play catch up on the preceding events. Also nobody has mentioned the well developed T-Cell that they descended into...even if they had reverted to basic power + attitude it would have been extremely difficult to hold an attitude in severe turbulence. And as far as I understand Direct Law still has roll-protection...making it even more difficult to keep wings level in severe turbulence. Plus it seems a greater diversion could have avoided taking them over the worst of it.... Strict Crew duty times and tight fuel margins may also be a factor here...

pmansion
29th May 2011, 10:48
Apologies if some of my terminology is wrong (I am merely a PAX!) However, it strikes me that this incident can be divided into two halves, before and after the return of the CPT.

First half, pitot tubes freeze giving unreliable air speed indications and AP disengages. PF continues to fly the plane for a short while but stalls. Pulls the nose up instead of pitching down. This could possibly have been prevented had he have know the attitude and ground speed prior to the failue of the Pitot tubes or followed some standard settings as per a previous post.

Second half, CPT returns from his rest. Perhaps he had been in deep sleep and therefore not fully on the ball. He's met with a dark cockpit the plane oscillating and a whole load of alarms sounding. Firstly, he must have said someting (even WTF) yet there is no mention of this in the transcript.
Question 1: Does he know the plane is in a stall or in a drive? You would have expected that the first things he would have checked are the airspeed, the altitude (dropping rapidly and appears to be displayed as shortlay afterwards the PF states that "we’re going to arrive at level one hundred") and the attitude (presumably still being displayed).

At 2 h 12 min 02 both pilots were reporting no (valid) indications. Question 2: What does 'no' mean. Are they referring just to air speed? This strikes me as unlikely. Could the FDR say that the instruments were showing certain readings whereas in reality some instruments were out?

However 40 seconds after the CPT arrives, the PF pushes forward on the stick, presumably in an attempt to dive and fly out of the stall (exactly the right thing to do). We know that the airspeed increased causing the stall alarm to resound. Question 3: What happens next? Does the PF pull back on the stick to get rid of the alarm (wrong thing to do)? Question 4: At 2 h 12 min 02 the thrust levers were are idle. Were they put there to reduce stresses on the plane in the dive / pull up recovery manoeuvre? Was this the right thing to do?

At At 2 h 13 min 32 there are further inouts by each pilot. Question 5: What were theses inputs (push down or pull up)? Did they continue to attempt to recover from the stall or were they just sat there dumfounded with the nose pointing up?

nitpicker330
29th May 2011, 10:55
Quote from FCOM 1

"ALL PROTECTIONS ARE LOST IN DIRECT LAW"

Other crews have been there and done that before and lived to tell the tail.
The storms they inadvertently flew into contained severe turb and super cooled water drops too.

HalloweenJack
29th May 2011, 11:34
if their are any A330 FO`s or captains here - have you tried stall recovery at FL350 or above?

YorkshireTyke
29th May 2011, 11:36
I'm glad wafelbolletjes has it right.

It must be so comforting to him.

fullforward
29th May 2011, 11:37
The more I read, the more clear it gets: the poor guys failed to recognize they were flying a fully stalled plane, got absolutely scared by the bells and whistles blaring all the time, rocking wings, winding down altimeters, a panicked captain shouting instructions and simply frozen at the controls (or even worse, giving inputs that agravated the situation), failing to do the only thing that would have saved the day.
Pure lack of proper training, basic airmanship & situation awareness.
It's hard to admit that a lot of us could have reacted exactly the same way...:{

A perfectly flyable aircraft turned into a gigantic coffin.

Of course there'll be endless theories about A330 systems, speculations on Boeing x Airbus, if this, if that etc...

nitpicker330
29th May 2011, 11:44
No I haven't but I don't think it would be a lot different to the stalls I have done at 22,000'. It would be a little more sensitive perhaps and i would need to be careful not to over control but the principles of stall recognition and recovery defined by Airbus in their FCTM and QRH would be the same:-

1/ reduce AOA

2/ increase energy.

opherben
29th May 2011, 12:04
The more I read, the more clear it gets: the poor guys failed to recognize they were flying a full stalled plane, got absolutely scared by the bells and whistles blaring all the time, rocking wings, winding down altimeters, a panicked captain shouting instructions and simply frozen at the controls, failing to do the only thing that would have saved the day. Pure lack of proper training, basic airmanship & situation awareness. It's hard to admit that a lot of us could have reacted exactly the same way.
A perfectly flyable aircraft turned into a gigantic coffin.

Of course there'll be endless theories about A330 systems, speculations on Boeing x Airbus, if this, if that etc... "
Since accident investigations are carried out to primarily prevent future similar occurences, and since to me it is clear that the crew knew the aircaft was in a stall, but based on control input evidence failed to recover from it, IMHO the effort should next focus on why they failed to initiate recovery.
Here comes to play a major role of Airbus system design, like it or not. With substantial personal experience in both own circumstances and other's, there must follow-on a drastic system redesign:
a. A human is unlikely to adapt well to changing control laws. Why is someone, used to not trimming, start trimming all of a sudden while he is already task-overloaded.
b. Why would anyone have an autoflight system obstructing/ overruling pilot control inputs and decisions, in a stable transport aircraft. Believe me I have likely much more experience than most of you flying variable stability aircraft and rotorcraft. There is no need to override a pilot control motion, just to properly design the flight control system such that there is almost no likelihood of the pilot damaging the aircraft to become unflyable. This must be coupled with proper pilot selection and training. Too expensive for the airline? choose another.

The CSS (Control Stick Steering) Boeing design, an arrangement I flew as example on the Douglas A-4H Skyhawk, enables autopilot flight during which the pilot can make desired changes, small or substantial, by synchronizing autopilot feedback signal (nullifying it) in the channel the pilot has applied force onto, such that it recognizes the new desired attitude upon pilot control pressure release. Simple and natural for the human in flight, during blue skies and in emergencies.

I would never pilot an aircraft with not only a mind of its own, such as trimming, but also limiting my AOA command, whether within the flight envelope or out of it. As captain it is my call, I know how to fly it better than any lead system engineer, fill reports later, in 36 years of flying they were few but all very well accepted and approved.

The current modern pilot flight displays are overly saturated such that no regular apt and trained human can quickly build in his mind a dynamic aerial situation. 60 year old captains would need at least double the time for that. In research simulator flights, 18 out of 19 seasoned and young pilots alike, failed to recognize and act upon erroneous FMA readings and below glidepath approaches. To me this is more than obvious, and leads to e.g. a Boeing 737-800 flying an auto-ILS with 1:50 of idle throttles just to stall it before the threshold, without pilot reaction, till it was too late. You guys fly them and should be well aware of this.

Mimpe
29th May 2011, 12:05
Sounds like the common sense immediate response to the stall warning was ignored, but the deceleration could have created a somatogravic illusion ,shared by all, for false nose down pitch sensation, hence the repeated and probably confused "pitch up" commands.

If thats the case, everyone would have had to be ignoring the AI, the stall warning, and the angle of attack indicator....very very strange....

A worst case scenario would combine it with a tail heavy loading configuation but that doesnt appear to be the case.

Sadly, they just couldn't work out out how to fly a stalled aircraft, no ASI, albeit in very bad weather which was avoidable...

spornrad
29th May 2011, 12:06
Ask21,
good thoughts, especially about the trim effect on aoa of the stab. I fly only small planes, but I guess the report is simply not providing enough information for a sound judgement.
I would not be surprised if the final conclusion will be that this stall, fully developed, was unrecoverable. I doubt if such a scenario was ever flight tested during certification. Certainly not without a drag chute installed.

JJFFC
29th May 2011, 12:11
Human factor is the only cause of the stall.

Whatever is the configuration of the computer, when stall warning : nose down.

Never a computer will prevent you from recovering from a stall if you nose down.

Both american and european authorities says that 80% of the crews earing a stall warning don't nose down at first bacause of a human factor.

The challenge is to train the crews to react like a top gun and not like a civil servant.

nitpicker330
29th May 2011, 12:15
Dropping a wing is taught in unusual attitude recoveries on Boeings if you find yourself with a very high nose attitude and the speed rapidly heading south. ( and at the same time reducing thrust to help to help the nose down pitching moment )

Mimpe
29th May 2011, 12:22
There could have been a deceleration somatogravic pitch down illusion causing the erroneous pitch up commands. But 3 minutes or so is a long time to keep that up - I'd be surprised if the artificial horizon and the angle of attack indicator were not functioning, and even more surprised if they werent referenced automatically in the stall.

opherben
29th May 2011, 12:26
To recover a stall, forward sidestick control motion is required. It was recovered once then the pilot longitudinal control moved aft and stayed there. The rest about such things like anti-spin chute, recoverability etc... may be important but irrelevant to the specific stall recovery.

nitpicker330
29th May 2011, 12:28
Cricky do any of you fellas read previous posts?

Yes all the Attitude indicators where fully functioning.

The problem was with the Air Data Modules receiving crap info from the iced up Pitot tubes....

Some Aircraft have AOA displayed on the Primary Flight Display but in this case I don't think AF do. Certainly my Airline and many others do not on any of our Aircraft types.

SoaringTheSkies
29th May 2011, 12:36
I'm sorry, I'm losing the overview.
Can somebody please remind me, what the margins were in the given conditions?
Obviously, the air was relatively warm yet below dew point. How can we interpret that they couldn't climb higher because of the temperature gradient being shallower than expected? Was that just referring to the tops of the cb being above their ceiling at that time?
What's the speed margin between Vmmo and Vs?
What's the AoA in normal flight at that altitude and what's the Stall AoA? (did I see it's only 6°?)

What triggered the 13° nose up trim on the THS? What impact would that setting have, along with fuel trim aft, on their chances of recovering from a stall if they had positively identified it in the first place?

With so many indicators being unreliable or not available, what "direct", that is aerodynamic or "seat of the pants" feedback would you have in a machine of that size with FBW controls? Obviously, there's no feedback from the control surfaces, there's no stick force to overcome (or rather to soften when the control surfaces get into turbulent air from the stalled wings)
Can the turbulent flow be felt through the airframe?
I honestly have no idea if those guys would have had any primary means of identifying the stall, given that the secondary means (read: instruments) were unreliable.

Also, I've read a lot about "law changes" in this thread, how does an AB pilot stay aware of what law what control axis is in at any given point? I'm sure there's nice flow charts in the documentation, but I wonder how many distinct states of flight law degradations there are and how often the system is allowed to change between them.

If, and it might, this turns out to be a case of "loss of situational awareness" (or rather: they never gained awareness of the situation they were in), it begs the question how complex the situation was when it was presented to them. A simple AoA indicator might have made all the difference to them.

The interface between the automation systems and the pilots seem to be the most difficult part of any design these days. How does the system present all the relevant information while not overwhelm the pilots? And this in a situation where the system is forced to give up since it's parameters are outside what it knows to handle. We could interpret such situations as the design engineers saying "this is a situation we have not considered / thought possible, over to you, pilots". This almost necessarily also means that it's hard or even impossible to say what information is relevant and what can be withheld. As a system designer, you are faced with the decision to possibly withhold information that might be meaningful to interpret the situation or to present information overload which doesn't help either.

I don't envy you guys who poke around at the levels >300.

ps: the system "knows" the AoA. If getting AoA display is an optional item on the aircraft order and AoA is not automatically displayed when the stall warning goes off because the feature wasn't ordered, that would seem sickening to me.

DeltaT
29th May 2011, 12:44
Well this is a discussion forum after all, and just as Nitpicker has pointed out is anyone reading previous posts at all??!! I am no authority at all, but having just done a shiney new Airbus rating I just practised Unreliable Airpeed last week(!), all the alerts are going off left right and centre, with 3 different airspeed indications in the cockpit, so putting TOGA on and pitching up 15deg (sounding familiar yet anyone?!!) you have a manouver which gives you an airspeed that should be at least what you get on initial climbout, then its time to see which speed tape has what you think it should have and compare with the G/S for at least ball park ideal.

fullforward
29th May 2011, 12:53
With all due respect, we basicly agree on the fundamentals: more training, more situation awareness.
Systems redesign? Very unlikely.
I cannot envisage a better scenario for this ill fated plunge into the ocean than the described.
I have some good thousands of hours on both designs: Boeing and Airbus.
Both have their virtues and flaws.
It's very unlikely that systems control design have anything to do with the outcome.
The lack of 'aviate' certainlly have...
If they ever trained high altitude stall recognizing and recovering everybody would be probably at thome at this time.

nitpicker330
29th May 2011, 12:55
Thanks bud and congrats on the conversion.

But please don't pitch up to 15 deg other than on TO below acceleration height!!:ok: Remember there a 3 different phases mentioned:ok:

fullforward
29th May 2011, 12:56
No offense: are you sure you're Bus rated?
Were in the earth you're taught to TOGA and rotate to 15 degrees, upon a loss of speed indication and stall warning at 35.000'??
Please, go back to your FS.

nitpicker330
29th May 2011, 13:01
You know what I think is that a lot of Pilots don't know the normal performance to expect on their Aircraft. ie normal CLB pitch and N1, Normal CRZ pitch and N1 and normal DES pitch and N1 ( yeah yeah idle !! )

If don't really know what's normal how could you know what to set when the **** hits the fan? Like in Iced Pitots or Volcanic ash flameouts etc...

I've asked FO's in the past what pitch attitude and N1 should we have in cruise now, don't look ( cheater := ) Quite a few got it wrong by quite a bit.....

GC_Graybeard
29th May 2011, 13:04
anybody of you fellow pilots out there have been through this
(or something similar)?



approaching CB killer cell without seeing it (why?, wx radar fault?, too-fast buildup?)
entering the outer downdraft surprisingly (cpt woke up?), (ice)
entering low-pressure inner updraft (water)
back in the outer zone (N.E.) with new massive downdraft

aside from the overwhelming (and distracting) body of
technicalities, can (has it been shown somewhere else)
a large A/C survive this encounter? With what probability?

I remember a similar encounter: Pulkovo 612 which
came out of a large CB in a flat spin (is this still valid?),
where the PF tried to "fly over" the mess and failed.

Would AF447 PF try to "overfly" the "turbulence" that
he (obviously) didn't know what it really was (otherwise,
he wouldn't be heading straight into it).

This is a question of a layperson, so please pardon
any wrong assumptions.

Thanks & regards

John James
29th May 2011, 13:05
Been following this and my amateur .02 is:
who has not fallen victim to the tyranny of the urgent at some time or other? - but tres dangerous in a cockpit..:suspect:

nitpicker330
29th May 2011, 13:08
Oh another one........

To save you from reading previous posts that have addressed your question I'll answer it for you again.

Yes, this has happened before in much the same circumstances as AF 447.
Other Airbus and Boeing types have entered CB's by mistake and lived to tell the tail. CB's large enough to injure Pax and freeze the pitot tubes with super cooled water......

GC_Graybeard
29th May 2011, 13:20
nitpicker330:

I read the posts, a lot of them, but not all 850+, so
sorry for missing some important parts.

I read many of your posts too and I'd like to ask
you as an AB driver: can you understand, why the
PF pulled with N1 100%? Did he try to get out?
Sometimes, subjective assessments by the right
people are more instructive than loads of technical
detail.

But: maybe I'm completely on the wrong track.

fullforward
29th May 2011, 13:57
We can assure you: they didn't tried to pass over the CB.
One explanation why they pulled back an already stalled airplane is confusion, lack of proper training, panicking, etc.

maynardGkeynes
29th May 2011, 13:59
@Flyerbob

As I noted earlier, the core difficulty faced by the crew was that the standard practice of using pitch + power to maintain safe flight without air data didn't seem to be working, and the problem is that it won't if the aircraft is already stalled. With the airbus' FBW [fly by wire] system and passive stick, the crew would have none of the force or buffet cues through the side-stick that might have told them this. Thus, once they stalled, with no instrumentation or VH, this was for all practical purposes unrecoverable in an Airbus. Under the circumstances, at night with no visible horizon, even an exceptionally well trained and experienced professional pilot would have lost situational awareness and would not have been able to discern the pitch attitude of the aircraft. I don't see how they can be blamed for their actions in the cockpit once the problems developed in an Airbus.

fireflybob
29th May 2011, 14:03
at night with no visible horizon, even an exceptionally well trained and experienced professional pilot would have lost situational awareness and would not have been able to discern the pitch attitude of the aircraft.

maynardGkeynes, so what about the pitch displayed on the attitude indicators?

John James
29th May 2011, 14:15
well this pax is adding AirFrantic to its no fly list
BrutishAir has been on there for a while...
and I am thankfully never going to India
j

ECAM_Actions
29th May 2011, 14:52
As far as can be determined, all three ADIs (Attitude Direction Indicators, or artificial horizons in layman's terms) was FULLY FUNCTIONAL.

As for pitching to +16 degrees of pitch at TOGA at FL380 (above optimum cruise alt for the weight and conditions)...

To quote the report:

The airplane’s altitude reached its maximum of about 38,000 ft, its pitch attitude and angle of attack being 16 degrees.
I'm not very good at English :} but this is telling me that the PITCH ATTITUDE WAS +16 DEGREES.

Anyone care to explain why this could possibly be considered a safe pitch attitude at FL380?

I can understand lots of alerts confusing the crew, but seriously, does anyone actually think that +16 degrees of pitch at high altitude is going to enable the aircraft to maintain a healthy airspeed?

The Ancient Geek
29th May 2011, 14:57
As a simple-minded Twotter driver there is one factor here which seems critical to me. If the stall warning sounds I know to get the nose down in a hurry then grab for the apehangers to add power.

In this case the stall warning only sounded (twice?) briefly which was probably the critical misleading clue which convinced the crew that they were not stalled.

If the stall warning had behaved as expected by any sane pilot and sounded continually during the stall then any sane pilot would have realised that the aircraft was indeed stalled and applied the correct recovery.

Why the hell did the stupid automation silence the stall horn ?
THIS SHOULD NOT HAPPEN :ugh::ugh::ugh:.

ECAM_Actions
29th May 2011, 15:03
Why the hell did the stupid automation silence the stall horn ?A great question. The systems silenced it because the IAS fell below 60 kts for a time. This caused the FWC (Flight Warning Computer) to silence the STALL warning.

It should be that any time stall AoA is sensed with the aircraft in the air mode that the stall warning sounds. Airbus must have assumed that if the IAS is < 60 kts then the aircraft is on the ground even if the weight on wheels switches say it is in the air. There is no logical explanation for it silencing the stall warning based apparently on IAS alone. :eek:

I'd love to know why display of AoA on the PFD is a very expensive paid-for option. IMHO knowing the AoA is at least as important as knowing IAS, if not more so, and should be a mandatory instrument/display.

Garrison
29th May 2011, 15:04
If you think about what could have been done to prevent this accident, rather than about whether the crew were competent/incompetent or whatever, it seems as though if they had had available the information that we have from the FDR, ie alpha, airspeed and descent angle, they would have recognized the problem immediately and recovered. But that info was not provided evidently because the system designers considered this scenario impossible. But three identical pitots known to be able to be overwhelmed by ice are not triply redundant; they are a single point of failure. The airplane -- any airplane whose systems rely so heavily on airspeed -- needs a truly alternate airspeed source, a full-time angle of attack indicator, and a stall warning that does not go to sleep and then wake up at inopportune moments.

ST27
29th May 2011, 15:10
well this pax is adding AirFrantic to its no fly list
BrutishAir has been on there for a while...
and I am thankfully never going to IndiaSo you've decided to spend the rest of your life hiding under your bed, since the riskiest part of a flight is the drive to and from the airport, rather than fly on some the safest international airlines? British Airways hasn't seen a fatal accident that could be attributed to the airline since it was formed. It's been something like 45 years since its predecessor companies had a fatal accident. They've seen millions of safe takeoffs and landings in the meantime.

In short, you're thinking irrationally.

gums
29th May 2011, 15:27
To the point, fellow poster. Thank you.

BTW, don't forget a FBW control scheme that may have contributed to the humans reacting to the situation in the manner they seemed to.

RansS9
29th May 2011, 15:30
The Wright Flyer had only one instrument....An ANGLE OF ATTACK METER.

( In this case a piece of string attached to a stick in advance of the wing leading edge out of updraft if I remember correctly). No need to remember power attiude values for various weights / density altitudes.

Totally infallible..probably not
Pretty damn close to infallible..I think so.

Diamond Bob
29th May 2011, 15:34
I can understand lots of alerts confusing the crew, but seriously, does anyone actually think that +16 degrees of pitch at high altitude is going to enable the aircraft to maintain a healthy airspeed?

Well, here's a guy who thinks the pilots were at first presented with information that the plane was flying too fast. This is the first I've heard this take on the situation, but read what he says:

First, an erroneous speed indication showed the plane was flying too fast. The pilots, believing the erroneous speed to be genuine, slowed the plane. As they did, the speed suddenly indicated the speed was too slow. But this speed indication, only 60 nautical miles-per-hour, was obviously incorrect.
Without accurate speed information, the pilots slowed the plane too much for the wing to provide adequate lift.

Black Boxes Tell What Happened To Air France 447 - National Fear of Flying | Examiner.com (http://www.examiner.com/fear-of-flying-in-national/black-boxes-tell-what-happened-to-air-france-447#ixzz1NkuwqUGC) Black Boxes Tell What Happened To Air France 447 - National Fear of Flying | Examiner.com (http://www.examiner.com/fear-of-flying-in-national/black-boxes-tell-what-happened-to-air-france-447#ixzz1NkuwqUGC)

Any comments on this theory? I hadn't heard myself that the pilots were at first presented with information that they were flying too fast. Could this be the reason for the nose up inputs? They thought they were in an overspeed condition?

182flyer
29th May 2011, 15:41
Let's return to Basics:

When I started flying a long time ago, the very first thing my FI taught me was 'in any abnormal situation: FLY THE AIRCRAFT'.

When I see the altimeter winding down real fast and the VSI confirming that with a high neg reading, first thing I ask myself why I'm going down and the only answer can be

> I'm in a severe ND attitude (which they were not, as they could see on
the artificial horizon with a glance).
> a severe downdraft by meteorolical cause (but NOT several thousand
ft./ min!)
> no or nearly no lift (which was the cause, as we now know).

How can I create lift? By building up speed, so NOSE DOWN.
Really quite simple.

If the AF pilots didn't do that, they EITHER
> paniced (not so far away; I've seen it happen) OR
> reacted by the book: Nose up and GA pwr (Standard procedure, as
written in several postings).

I wouldn't blame the pilots for either reaction, the first is normal (panic is caused by simple overstress in an abnormal situation and cannot be 'trained away', only the level of entry into the panic state can be hightened) and the second leads to the question if the system OVER-trains todays pilots. Could it be that the system presents a so specific solution to every situation, that the simple basics of flying disappear behind the 'DO THAT, WHEN THAT HAPPENS'?

Does the system train away common (flying-) sense?

Please don't hang the subject up to high into technical terms, try to put yourselves into the pilots and stick to basics.

Leaves two questions:
> The captain arrived quite fast after the beginning of the situation. He
was not fighting the situation (as was the PF), and not trying to assist
(as was the PNF). What would he do? My guess is, he'd try to get an
overview of the situation the aircraft is in first thing. He should have
recognized the stall and ordered a ND attitude. Did he and the PF didn't
comply (panic?). Or did he not, than why not.
I hope the CVR script will reveal that.
> Could the crew break the stall, even if they had recognized it? With an
AOA of more than 40° that wouldn't have been to easy: With practically
no clean airflow over the elevators (close to a flat spin), those may not
have responded to a ND input, even if it had be given. Would they have
had the time to throw out the LG or even deploy the thrust reversers in
order to get a ND momentum? And would the FBW systems have let
them?

The whole story focuses onto one simple subject: The technocrats are over-stressing the pilots. It over-emphasizes specific reactions to specific situations (which computers can comply to much better and faster).

We know of enough incidents (that the pilots were able to walk away from), where cpmpletely unorthodox reactions saved the day.

The solution? Have airplanes be flown be computers (only) or ... return to basics and focus onto what we were trained for in the firt place:
FLY THE AIRCRAFT!
 

maynardGkeynes
29th May 2011, 16:08
maynardGkeynes, so what about the pitch displayed on the attitude indicators?@ fireflybob

You are correct: attitude, derived from a combination of rate and attitude gyros should still have been reliable. At the same time, if the attitude of the aircraft is nominal [normal], power is nominal, but vertical speed is indicating -10,000ft per minute, the most likely cause is that the airplane is stalled. The problem the crew faced is that 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. With the airbus' FBW [fly by wire] system and passive stick, the crew had none of the force or buffet cues through the side-stick that would have told them that were in a stall, which would also have explained why the pitch + power response, which seemed not to be working for them, was to no avail. I believe that under the circumstances, the stall was effectively unrecoverable.

ECAM_Actions
29th May 2011, 16:16
Here's an idea: have secondary pitot tubes in the airframe that can be deployed like a RAT should the primaries be lost. At least it might provide sufficient time to recover and apply the correct pitch/power settings.

pmansion
29th May 2011, 16:19
@182flyer

You need to read the transcript properly. Approx 37 seconds after the Captain entered the cockpit the PF made pitch-down inputs. Apart from the aircraft speeding up and the stall warning re-sounding we know little about what happened next.

As others have said the stall warning coming back on may have led a confused crew into thinking they were making matters worse. It seems unbelievable that there is not a warning to warn the the plane is currently in a stall.

I wonder if there will be three recommendations out of this...

1) A warning that the plan has stalled and is falling
2) AOA indicator
3) A more robust (manual or automated) way of allowing the pilot to return to the previously good settings (attitude and power).

Zorin_75
29th May 2011, 16:25
The problem the crew faced is that 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.At the beginning of this mess the a/c was not stalled. A stalled plane won't climb 7000 ft/min. The question that can't be answered so far is why didn't or couldn't they maintain pitch and thrust at this point.

> reacted by the book: Nose up and GA pwr (Standard procedure, as
written in several postings).I believe that should be true for approach to stall. When already stalled I suppose even Airbus procedures would call for nose down?

Garrison
29th May 2011, 16:26
> Could the crew break the stall, even if they had recognized it? With an
AOA of more than 40° that wouldn't have been to easy: With practically
no clean airflow over the elevators (close to a flat spin), those may not
have responded to a ND input, even if it had be given.


I have talked with several aerodynamicists who were generally in agreement (just theoretically -- no first-hand knowledge) that the A330 probably does not have an unrecoverable deep stall mode and that the airplane would have responded to a nose-down pitch command. In fact there was a brief moment during which an AND command was given, the airplane began to pitch down, and then lo and behold the stall warning came to life and discouraged the pilot from continuing the experiment. It would have been necessary, if I understand the control laws correctly, to manually trim out of the full ANU stabilizer setting of -13 deg. An important point is that the flight path was 25-30 degrees down, and so a stall recovery by reference to the PFD would have required putting the nose 20 degrees or more below the horizon.

Graybeard
29th May 2011, 16:27
ECAM, how would you prevent the secondary pitots from icing up?

Better to have pitot probe heat robust enough not to allow icing up.

Then educate the autopilot to go into pitch and power hold mode at loss of airspeed, and remain, engaged, in Normal.

torquemada60
29th May 2011, 16:28
I am not a pilot, I am not a technician or aviation specialist. I am your average passenger who flies constantly around the world.
Gentlemen, most of you are professionals, paid to do a job. I could care less about your problems or issues with such and such aircraft. I am paying you to fly me from A to B fast and safe.
Reading through the comments on this web site, it appears that 3 pilots made wrong decisions. They chose to fly through a storm when many airlines had deviated their course by miles. The Captain went for a nap knowing there was a storm ahead. The two copilots appeared to be poorly trained and unable to cope with issues.
I hope Air France will be punished and the families compensated for what appears to be recklessness, arrogance and a total lack of professionalism from the pilots.
228 people died as a result.
As far as I am concerned I will never fly Air France again and I will tell as many people as possible to do the same.

Mornington Crescent
29th May 2011, 16:37
I think I have read all the contributions. There is no mention of coffin corner in the thread.

Does the AB 330 not have such a problem? Could someone with practical knowledge of the aircraft estimate whether at the assumed weight and altitude what margins there would be at the cruising altitude. Also would the climb to FL380 have put them into coffin corner? Once there of course (if it exists for the AB) the aircraft would be buffeting with an increase or decrease of speed (Mach No.)

The Ancient Geek
29th May 2011, 16:40
the stall was effectively unrecoverable


It would have been easily recoverable if the stall horn had worked properly.

J-Class
29th May 2011, 16:51
If you think about what could have been done to prevent this accident, rather than about whether the crew were competent/incompetent or whatever, it seems as though if they had had available the information that we have from the FDR, ie alpha, airspeed and descent angle, they would have recognized the problem immediately and recovered. But that info was not provided evidently because the system designers considered this scenario impossible. But three identical pitots known to be able to be overwhelmed by ice are not triply redundant; they are a single point of failure. The airplane -- any airplane whose systems rely so heavily on airspeed -- needs a truly alternate airspeed source, a full-time angle of attack indicator, and a stall warning that does not go to sleep and then wake up at inopportune moments.

Garrison, I'm with you. Indeed, this view hasn't changed much since I made a similar point on p.24 of this thread (before the BEA report was published) where I said:

"Surely AoA (and perhaps a GPS speed indication for good measure) would be very helpful in instances where airspeed indicators have gone doolally and the aircraft computers are assaulting with pilots with a bunch of not necessarily consistent error messages and alarms?

All modern aircraft rely on system redundancy, but can any system be deemed truly redundant if it relies on the same components on each of its legs? (I'm imagining that more than one pitot tube iced up). Given the problems of producing 'true' redundancy in a single measurement system, why not admit that visible workarounds should always be available to the pilot?"

maynardGkeynes
29th May 2011, 16:53
the stall was effectively unrecoverable
It would have been easily recoverable if the stall horn had worked properly. It was working properly, which is part of the problem. The captain was not in the cockpit at the time of the first two stall warnings, and only heard the third. One must question, therefore, the procedure to call him back into the cockpit and then, further, to allow him to direct the crew's response.

ST27
29th May 2011, 16:54
As a simple-minded Twotter driver there is one factor here which seems critical to me. If the stall warning sounds I know to get the nose down in a hurry then grab for the apehangers to add power.

In this case, the first question that needs to be answered is why the PF decided to pull the nose up when the aircraft was in otherwise stable flight at the time the autopilot disconnected. That might explain the mindset that had to be overcome to get things under control again.

In this case the stall warning only sounded (twice?) briefly which was probably the critical misleading clue which convinced the crew that they were not stalled.

While the report isn't perfectly clear, the way I read it, the stall warning sounded at least three times: Twice immediately after the PF initially pulled the nose up, while they were in the steep climb, and once after the climb peaked and the aircraft regained airspeed as it began to fall. The report says the aircraft was stalled for the remainder of the flight, so I suspect the stall warning was sounding continuously thereafter.

The PF reacted to the first stall warnings by trying to lower the nose during the climb, but then later applied TOGA power and pulled back before they had recovered. At some point near the top of the climb, he dropped the throttles to idle, but still maintained the nose-up input.

As they started to fall, he again tried putting the nose down, but when the speed picked up, and the stall warning sounded again, returned to full nose-up input, which he retained to the end, even though the attitude was something like +15 degrees, and the AOA+35 degrees. By then, the speed sensors were working again, so all his instruments should have been working as well.

If the stall warning had behaved as expected by any sane pilot and sounded continually during the stall then any sane pilot would have realised that the aircraft was indeed stalled and applied the correct recovery.

That's a good question, which brings me back to what the PF's midset was, and why he didn't react correctly to the stall warning in the last 2 1/2 minutes of the flight, even though the warning must have been sounding continuously. That should have been enough time to reconsider what he was doing, and try something different.

Why the hell did the stupid automation silence the stall horn ?
THIS SHOULD NOT HAPPEN

From the BEA news release:

"When the measured speeds are below 60 kt, the measured angle of attack values are considered invalid and are not taken into account by the systems. When they are below 30 kt, the speed values themselves are considered invalid."

Perhaps they consider the instrumentation to be unreliable at those low speeds? The lack of wind noise past the cockpit should have been a clue that they weren't making much headway.

Even if they didn't suppress the alarm when the speed dropped, would it have sounded when the AOA, which is the primary input, dropped to only 4 degrees, as it did near the top of their climb?

Me Myself
29th May 2011, 16:56
The amount of rubish posted on this site is just bewildering !
Some professional Bus drivers have posted over and over again what the recovering procedure is, was at the time ! What else do you need ?
Attitude and thrust ! Period !


Had the skipper been at the controls, this would never have happened and yes, it is a shocker to see a captain go to the bunk while the aircraft is toying with a TCZ. This is another no brainer and all this politically mumbo jumbo won't hold for very long.
BEA carefully chosen words in order to control the leaks is not going to change the fact that the next report will be absolutly shattering.
More than meet the eyes doesn't apply in this case but rather what you see is what you get. Plain, simple and brutal.

aguadalte
29th May 2011, 17:08
Torquemada60Reading through the comments on this web site, it appears that 3 pilots made wrong decisions. They chose to fly through a storm when many airlines had deviated their course by miles. The Captain went for a nap knowing there was a storm ahead. The two copilots appeared to be poorly trained and unable to cope with issues.
I hope Air France will be punished and the families compensated for what appears to be recklessness, arrogance and a total lack of professionalism from the pilots.
Don't worry Torquemada, AF is already "paying" and the pilots have already paid, with their lives. With AF, and its pilots, its a question of "company culture". We all know that...

But regarding the Report,
I must say, that I find the (3 pages) BEA report quite insufficient and vaguely accurate. Its quite tendentious, because it doesn't give all the relevant information. One has to read between the lines to figure out that a lot of relevant information was not aired, yet.

First of all, because it doesn't give us a clue (apart from a couple of phrases between the two co-pilots, that point to the general idea that they have lost valid indications and that they were in bed weather) of what was really happening in the cockpit during those 3 or 4 minutes:

- 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?

This report has a lot of unanswered questions and a lot of information gaps.

I think we should render the benefit of doubt to the crew, before crucifying them on the public arena. I do know its not "natural" to pull-up during a Stall, but I'd like to know more about what has really happened in that cockpit, before judging them.

Again, as to "Company Culture", as to why enter the thunderstorm, as to lack of formation, etc. I think we should get back to the times when, Safety was never compromised in lieu of commercial revenues, "Fuel Saving" programs, low cost tickets, passenger protection programs, etc.
Do you find any logical explanation to why is it possible to pay less for a two hour flight ticket, than for a 15 minute ride taxi? Well, millions of passengers do!

awqward
29th May 2011, 17:10
(Peter?) Garrison, could a full tail stall develop with severe icing build-up (combined with an aft CG)....It seems the pitot tubes iced up...the met conditions were highly abnormal...is it feasible that there was also a failure of the tail de-icing system? Although I have to agree with Torquemada60: the Capt should not have left the FD with the impending CBs ahead and they should have made a larger diversion (fuel margins notwithstanding)

armchair_pilot
29th May 2011, 17:15
IMO there's too much over simplification going on here, I don't believe the pilots were incompetent - even 20 years after I last flew anything the recovery from a stall is ingrained. Hence:

(a) Are we sure that the nose up trim was added manually rather than automatically by the aircraft ?

(b) Why did the pilot keep pulling up when, with our near perfect knowledge, the opposite would have been more successful ? I'd suggest that the cockpit's displays had completely confused the sufficiently experienced crew and they were tracking a plausible (but wrong) hypothesis based on what they concluded from the displays.

(c) Perhaps there is something wrong with the Airbus assumption of how crews process data, particularly conflicting data combined with lots of visual and aural warnings, set against a system (=the plane) whose outputs depend upon which mode the system is in ?

(d) It would seem that the Airbus approach to automation works in 99.99% of the time and during that time is probably the most efficient and safe approach. However in the remaining 0.01% of the time a 'deep s***' mode is needed whereby only the basics are displayed & communicated. If these had included a height, an angle of attack and a (perhaps GPS calculated) speed, things would have become clear to the crew.

(e) How much height is needed to recover from an A330 near stall, stall and deep stall ?

bearfoil
29th May 2011, 17:19
Garrison

Your post is a fine starting point to unwind this accident. The downside, is that what you have written is well known, and to this moment, unaddressed.

How does one tell a Butterfly from a moth?

smith
29th May 2011, 17:20
Could altitude and speed data from gps not be entered into the flight computers and compared to pitot static data with any major deviation between the the two setting off alarms? SLF here :=

robdean
29th May 2011, 17:49
From my perspective (psychology qualified) the statement by the PF of "no valid indications" is significant. It strongly implies to me that he was sufficiently disoriented by invalid readings from SOME instruments to become incapable of distinguishing whether he had any useful information in front of him at all.

This reaction that 'it has all gone haywire' is lethal because it undermines the best (and often only) means you have to regain situational awareness, which is to work the data. This has been true since the days of doped fabric, and has led to a consistent litany of stalls and CFIT.

Complex modal fbw systems add the peculiar complication that the aircraft itself can, in a manner of speaking, lose situational awareness itself. Of course this is purely algorithmic, but can lead to 'assisting' the pilot in a task at odds with his actual intentions, or inhibiting a warning as a false alarm, despite the fact that given the current flight phase and circumstances such a warning is probably urgently appropriate.

That said, it looks like plain dumbness rather than a side-effect of complexity when a stall warning seems to activate whilst approaching stall but then to quit in full stall, only to trigger again upon attempted recovery.

thermostat
29th May 2011, 17:49
The ancient Greek.

The stall warning discontinued when the speed was BELOW 60 Kts. How in blazes do you fly a large jet at 35000 ft at a speed of 60 Kts ?? At that height the speed has to be above 270 Kts. The stall warning is of no use to the pilot below 60 Kts when your plane should be at 272 Kts IAS at 35,000 ft, and 0.80 mach speed. The normal speed was 0.82 M and they slowed to 0.80 because of the turbulence. Flying into CBs close to the "coffin corner" is nuts. Remember too that the 'plane rose to 38,000 ft which meant they had no room for error.

Garrison
29th May 2011, 17:51
There are all sorts of possibilities, including an unreported (by ACARS) tail deice failure, but a good Occamite would say that what we have here is sufficient unto itself. The vulnerability of the Thales pitots was known in advance; and the proneness of flight crews to become utterly confused and to do seemingly insane things when confronted with inconsistent airspeed/attitude information and uncertainty about systems behavior is well known from previous incidents, notably ones involving pitot icing. So even the fragmentary information we now have is not inconsistent with history (though it seems to be inconsistent with what a lot of pilots think they would have done if they had been there) and shouldn't astonish us. What would be astonishing is if there is no rethinking of pilot/flight data interfaces, especially with regard to AoA, after this -- though once the dust settles this, like previous crew-befuddlement accidents, will probably come to seem more and more like a freak outlier and less and less like a call for systems improvement.

bearfoil
29th May 2011, 17:55
Exactly so. The failure of complex systems used to be less emergent than recently. I remember flicking instruments with my index finger, long after I could have expected a result.

This will more than likely be an easily reducible stream of data leading to insufficient flying speed, and no readily available method to increase it.

Is there an Unreliable AoA in the FCOM ? Will there be?

ST27
29th May 2011, 17:58
Reading through the comments on this web site, it appears that 3 pilots made wrong decisions. They chose to fly through a storm when many airlines had deviated their course by miles. The Captain went for a nap knowing there was a storm ahead. The two copilots appeared to be poorly trained and unable to cope with issues.You are rushing to judgement, prior to the release of the final report. Don't let the media spin on things warp your views of what really happened. Nothing so far says that the crew was poorly trained. You have simply made that assumption. There are too many inconsistencies in the report to understand what was going on, what the crew saw, and why they reacted the way they did.

As far as the captain going for his rest period, why do you see that as a problem? Flying across the equator through less-than-perfect weather is fairly common. The First Officer, who was presumably flying at the time, had more than twice the experience on that type of aircraft as the captain. The captain may have had full confidence in his abilities.

I hope Air France will be punished and the families compensated for what appears to be recklessness, arrogance and a total lack of professionalism from the pilots.
228 people died as a result.Now you are truly jumping to conclusions before the incident has been fully explained. Judge, jury, and now you want to assign punishment even though you don't understand what transpired and why. I hope you never get on a jury, as it doesn't appear you would be swayed by any evidence that didn't fit your fixed opinion.

Arrogance? Recklessness? Lack of professionalism? Don't be absurd.

bearfoil
29th May 2011, 18:03
Although it will undoubtedly be a very minor finding in the Final, in France it is considered tres gauche to question a man who is doing his job. I cannot say I have a problem with that. These were all eminently qualified men.

ST27
29th May 2011, 18:05
Could altitude and speed data from gps not be entered into the flight computers and compared to pitot static data with any major deviation between the the two setting off alarms? SLF here

The critical speed is airspeed, not physical speed over the ground. Consider a simple case where there is a 200 knot tailwind. The result will be a 200 knot variance between the GPS and true airspeed, yet the aircraft would be perfectly happy in the air. No warning needed.

thermostat
29th May 2011, 18:09
Garrison

Is it possible that the super cooled water that made the 3 different pitot tubes block with ice simultaneously, would also have prevented the AoA from moving thereby rendering it useless?
I don't think that some folks on this site realize the amount of chaos super cooled water can cause. At that altitude the air is so pure that the water cannot freeze. It needs some impurities for the ice to form. When this super cooled water came into contact with the aircraft it immediately turned to ice. It may also have formed on the nose and wings of the the 'plane making it heavier and changing the C of G.

Rananim
29th May 2011, 18:27
The autotrim and stall warning inhibit were lethal traps here.I love it when Airbus guys come on here and say its easy,just follow the procedure.The Airbus isnt so easy in non-normals is it?Its not really an intuitive a/c.How many different laws are there?Even an AIrbus guy didnt know all of them and had to be corrected.And this autotrim givesfull ANU in one LAW but a second later autotrim is no longer available because we're now in a new degraded law.And so the poor pilot who is used to autotrim is now stuck with full ANU trim.Hes got to second-guess what these Flight Computers are doing.In real time.And then the stall warning..on one minute,off the next even though the stalled condition hasnt changed.So when he did push down and the stall warning re-activated,he reacted instinctively and reversed his decision.My God,it would confuse the hell out of me too.And all of this going on in the middle of the night over the ocean with no tactile/visual feedback.No trim wheel.No control wheel.Just two sidesticks.The PF could be performing the direct opposite of the required recovery procedure and the PNF wouldnt be any the wiser.Myhat is off to you guys who fly this thing,itreally is.

Still,I expect they will still go with pilot error as probable cause.Technically,it was.But system design didnt help them any on this dark stormy night.

thermostat
29th May 2011, 18:31
182 Flyer

Basics unfortunately have nothing to do with flying a jet at high altitude close to the "coffin corner" and then having supercooled water (ice) block all 3 pitot tubes simultaneously, build up on the wings increasing the weight and changing the C of G. This is a totally different kettle of fish. The way to prevent this type of incident is to stay away from CBs when close to the coffin corner. That's what they didn't seem to have done.

EGMA
29th May 2011, 18:54
I note the report talks of 'nose up input'.

It may seem a daft question but what is the correlation between what the computer saw and what the pilot(s) joy sticks were doing? Are both the joy stick positions recorded?

edmundronald
29th May 2011, 19:11
Edmund......This is not new, before the Air Caraibis incident my Airline had a similar thing occur over the South China sea in an A330. They had their pitot probes ice up from super cooled water and they then had all the same things happen.
AP A/THR dropped out
Simultaneous overspeed AND under speed warnings
Alternate Law

Etc etc

They were initial hung out to dry but the union proved the Radar was at fault and the crew hadn't actually exceeded any limitations.

So, the Airline changed the Radars on all the 330's and changed the Pitot tubes to the newer model.

This is not a new thing..

Someone should find the Air Caraibes guys, interview them, and figure out why they were able to deal calmly and well with an issue that killed the AF guys; that should allow improvement of training.

pattern_is_full
29th May 2011, 19:13
Regarding the initial sudden climb:

"'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). The airplane was then at an altitude of about 37,500 ft and the recorded angle of attack was around 4 degrees."

So obviously to some extent the aircraft was climbing despite the pilot's attempts to lower the nose. Keep in mind that with a whale of a plane like this, there is a lot of inertia. It is not a maneuverable fighter jet.
__________________

On the question of using GPS as a substitute for pitot tubes - here's why it isn't useful (apologies to the 98% of pilots who already know this), especially at 35,000 ft.

The behavior of an aircraft is determined by effective or INDICATED airspeed. How much air is flowing over the airfoils and controls.

An aircraft at 35,000 feet flying at 500 kts, may show an indicated (pitot) airspeed of about 260 kts (depends on temperature) - because the air is so thin. More importantly, it will BEHAVE as though it is only going 260 kts, because there are fewer air molecules to hold up the wings or have an effect on the control surfaces.

The "magic" of the pitot system is that it measures the EFFECTIVE airflow at any given altitude, thereby fairly accurately reflecting how the plane will handle as the air gets thinner. (At least up to the point where Mach effects kick in - getting close to the speed of sound introduces its own issues.)

A GPS cannot do this. It only reports how fast the plane is actually moving, which says nothing directly about how much airflow the pilot has to work with. In addition, it figures in wind effects, which also have no direct usefulness in controlling the plane.

Pop quiz:

You are at 35,000 feet. The GPS says you are traveling at 400 kts due north over the ground, decreasing at 1 kt per second. There is a 60-kt jet stream blowing from the southwest (217°). Your stall speed (no flaps) would be 167 kts INDICATED, but your airspeed indicator isn't working. Your heading is 356°. Barometric pressure is 29.75 (but your altimeter is set to 29.92 as in all flights above 18,000 feet.) The air outside is -42° C.

Tell me how close you are to a stall. (You have 10 seconds to calculate this).

Doesn't work.

The reason planes still use a 160-year-old instrument for airspeed is that it remains the best tool for the job.

The Ancient Geek
29th May 2011, 19:24
The stall warning discontinued when the speed was BELOW 60 Kts. How in blazes do you fly a large jet at 35000 ft at a speed of 60 Kts ?? At that height the speed has to be above 270 Kts. The stall warning is of no use to the pilot below 60 Kts


If the IAS gets down to 60 Kts and the wheels are not on the ground then the aircraft must be very badly stalled. Disabling the stall warning makes no sense.
This is not a feature, it is a bloody stupid design error.

If the stall warning sounds all pilots are trained from PPL level to expect it to continue until the stall has been recovered. Stopping the horn while the aircraft is still stalled is dangerously misleading and IMHO is a major contributing factor in this accident.

ST27
29th May 2011, 19:31
If the stall warning sounds all pilots are trained from PPL level to expect it to continue until the stall has been recovered. Stopping the horn while the aircraft is still stalled is dangerously misleading and IMHO is a major contributing factor in this accident.

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.

Cows getting bigger
29th May 2011, 19:41
Dumb, single engine piston instructor here.

It would appear that everyone agrees that erroneous data from Pitot/Static/AOA gauge was a (the?) significant causal factor here. So, assuming that is the case and also assuming that pilots will remain fallible, doesn't the multi-billion dollar air transport industry owe it to the numerous casualties of many accidents to sort the sensor issue once and for all? We have achieved so much in aviation but continue to rely on a small tube (or set of) and some pin holes to measure dynamic & static pressure.

bearfoil
29th May 2011, 19:41
One of the pilots explained to us the unusual warm temps, and coupled with instability in roll on the way up, and an AoA of 4 degrees over the ToC, which was probably in excess of Stall, there are some unaddressed concerns, possibilities?

bearfoil
29th May 2011, 19:44
Dairy guy here cows. Remember, a lack of respect for the Physics is only very occasionally punished with such an outcome as 447's plunge. The Bottom line is what you see in equipment is not the best, but the best, considering.

keep the greasy side down

pattern_is_full
29th May 2011, 19:56
For ST27:

Perhaps. The report definitely notes that when the PF lowered the nose a couple of other times, the silenced stall alert CAME ON again - and the PF STOPPED lowering the nose in response to the alarm (or at least, at the moment the alarm came on - cause and effect is strongly circumstantial).

If you do something, and someone or something starts yelling "No, no, no!" - it is basic human nature to STOP doing whatever it was - even though it was the correct thing to do.

Shades of Buffalo - when the alarms went off, the FO "undid" the last thing she'd done before the alarm (raised the flaps she'd just lowered.)

The design of this alarm taught the AF PF in a very short period of time that "if you lower the nose, you will get yelled at. If you don't lower the nose, the alarm will stay quiet."

That is not good design.

CONF iture
29th May 2011, 20:02
Rananim, like very much your post but maybe you would like to correct it as a trim wheel is still available in the A330.

Flight Safety
29th May 2011, 20:40
At 1 h 55, the Captain woke the second co-pilot and said "[…] he’s going to take my place". Between 1 h 59 min 32 and 2 h 01 min 46, the Captain attended the briefing between the two co-pilots, during which the PF said, in particular "the little bit of turbulence that you just saw […] we should find the same ahead […] we’re in the cloud layer unfortunately we can’t climb much for the moment because the temperature is falling more slowly than forecast" and that "the logon with Dakar failed". The Captain left the cockpit.

Assume after the seat exchange, the PF noted the air temperature was higher than expected, thus stating his understanding they were thrust limited and therefore could not climb much higher in the warm air. This also seems to verify the previous weather discussions and ice formation at that altitude, related to this accident.

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).
Note 1: Only the speeds displayed on the left PFD and the ISIS are recorded on the FDR; the speed displayed on the right side is not recorded.
Note 2: Autopilot and auto-thrust remained disengaged for the rest of the flight.
At 2 h 10 min 16, the PNF said "so, we’ve lost the speeds" then "alternate law […]".
Note 1: The angle of attack is the angle between the airflow and longitudinal axis of the airplane. This information is not presented to pilots.
Note 2 : In alternate or direct law, the angle-of-attack protections are no longer available but a stall warning is triggered when the greatest of the valid angle-of-attack values exceeds a certain threshold.

Much to discuss here. From ACARS messages, we believe the pitots iced over, causing airspeed disagreement resulting in disconnect of the AP and AT. The airplane responded to AP disconnect with a right roll, which the pilot tried to correct. Given that the pitots froze with the heaters on, the right roll could have been caused by asymmetric ice accumulation, wing fuel tank imbalance, or perhaps by the turbulence they were experiencing. From the text, it sounds like the first 2 stall warnings were brief in nature, and could have been false due to asymmetric ice on the AOA vain, or perhaps briefly induced by turbulent up draft. IAS was apparently 275kt prior to loss of airspeed on the left PFD. Assume the AT disconnect left the engines at the same power settings prior to disconnect. The PF realized the airspeeds had been lost, and that alternate law had been selected.

The PF response to the right roll is problematic. The nose-up component started a climb, which he already knew he did not have excess power for. We have no information that he increased power at this time. Why he pulled nose-up is a mystery. Maybe he thought the 2 brief stall warnings were false, maybe he wanted to try and climb above the icing or the turbulence. However he did not have reliable airspeed indication in these moments, to attempt this.

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). The airplane was then at an altitude of about 37,500 ft and the recorded angle of attack was around 4 degrees.

Control inputs at high altitude are exaggerated due to the thin air. Control inputs therefore have to be smooth, and a progressive pitch increase to 10 degrees and beyond would seem to indicate the PF understood this. Either nose-up control inputs caused the brief zoom climb, or perhaps an updraft bringing up warmer air contributed. What is sure is that by the time he reached 37,500 ft and the left airspeed returned, he only had 215kt, which was too low to sustain flight at that altitude. The left and right roll responses seem to indicate either the aircraft was near a stall, or the rolls were being caused by turbulence, and certainly the quick disappearance of the pitot ice condition indicated some passage from one air mass to another. However the aircraft got to this altitude with this low airspeed, it was now going to stall, no way around it.

From 2 h 10 min 50, the PNF tried several times to call the Captain back.
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 recorded angle of attack, of around 6 degrees at the triggering of the stall warning, continued to increase. The trimmable horizontal stabilizer (THS) passed from 3 to 13 degrees nose-up in about 1 minute and remained in the latter position until the end of the flight. Around fifteen seconds later, the speed displayed on the ISIS increased sharply towards 185 kt; it was then consistent with the other recorded speed. The PF continued to make nose-up
inputs. The airplane’s altitude reached its maximum of about 38,000 ft, its pitch attitude and angle of attack being 16 degrees.
Note: The inconsistency between the speeds displayed on the left side and on the ISIS lasted a little less than one minute.

When the 3rd stall warning occurred, the pilots pushed the throttles to TOGA (the correct move) and then continued to maintained nose-up inputs (bad move). This is inexplicable, and I can only think that maybe they fell back on training where they were taught to power out of a stall with minimum loss of altitude, which is training that has now been changed since this accident. For whatever reason, the continued nose-up inputs (or selecting TOGA perhaps?) caused the THS to trim to +13 degrees up. Then at some point alternate law 2 (abnormal alternate) must have been triggered, since the THS never moved down in response to later nose-down inputs. My thinking is that with the THS stuck at 13 degrees up angle, they were never going to recover the stall, unless they realized they were in abnormal alternate and had to manually trim the THS. Nothing from the BEA report seems to indicate they did this.

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. Note: When the measured speeds are below 60 kt, the measured angle of attack values are considered invalid and are not taken into account by the systems. When they are below 30 kt, the speed values
themselves are considered invalid. 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. The PF made an input on the sidestick to the left and nose-up stops, which lasted about 30 seconds.

When the angle of attack exceeded 30 degrees, this may have been the point where abnormal alternate law (alternate 2) kicked in, so no auto trim of the THS after that.

I could go on, but I'll stop here. The great mystery for me is the persistent nose-up inputs. The later nose-down inputs might have worked if they had remembered to manually trim the THS. Too many holes in the Swiss cheese here.

Admiral Shin
29th May 2011, 20:49
It really amazes me that there are so many super god like pilots opining here, all with super hindsight acting as if the data released so far give them a crystal clear picture of all the cockpit indications in this tragic flight. I can bet my last dollar that if we are ever able to simulate all the chaos and mess that had happened on this cockpit and throw them at a super airbus ace caught unaware, the outcome would have been no different.

In another life as a checker, after completing the sim check of a super ace to a very high standards we used the remaining time to conduct some extra excercises on really unusual attitudes with combinations of other failures...the plane went belly up, ace or no ace. We repeated it twice, same results. 2 years later, another sim check and super ace asked for another go at that exercise...he managed to save the plane but barely. He admitted he thought long and hard about it coming out with all the possible solutions in his head before the session. He was truly humbled and conceded that there were combinations of failures that are almost impossible to handled when one is caught unaware with not much time on one's side.

So, sky gods hold your peace. Thank your lucky stars that it did not happened to you. Hope that the manufacturers come up with equipments without all those design flaws; get the designers to think like average sensible pilots, not anal retentive hardnose savants who think that handling an inflight emergency is as easy as having brainstorming piss up in some soothing sequestered karaoke joint.

bearfoil
29th May 2011, 21:22
Again, if PF had not made himself aware of Law change, and was functionally still in Normal, these inputs would not do harm. (Roll left, full aft stick).
Dropping a/p does not command degradation out of Normal Law. Could he have been that far behind? It takes AD disagrees to autoselect ALTLAW. So at what point were they aware of AD disagree , and how long after that before they acclimated there 'get'/'got' to new parameters?

CI54
29th May 2011, 21:50
My 0.02:

The pilots must have thought they were in an overspeed situation. Horns blaring, rate of descent 10000+ fpm, no reliable speed indication, dark night, in severe weather, stall warning suddenly went off after pitching the nose up for sometime and then coming back on after pitching the nose down...

It's a pity they got it wrong. When in confused state, one would try everything to save the situation. They must have thought stick aft at full thrust was working since the stall warning actually stopped blaring. The thing they couldn't resolve was why were they still descending at a rapid rate? That's when one of them pushed the stick forward, which unfortunately re-trigger the stall warning. So they pulled the stick back to silence the horn, and the action did silence it. And all the while, they didn't have a valid 'speedometer'...

IcePack
29th May 2011, 21:53
Wonder what the r/h asi tape was reading. Amazed it is not recorded. If it was very high it may explain the back stick inputs. However use of the QRH would of been useful. Too distracted to get it out I guess.

182flyer
29th May 2011, 21:53
Oh yes, pmansion, I HAVE read that!

The first ND inputs were recorded between 02:10:05 and 02:10:51 -- the Captain re-entered the cockpit at 02:11:40.

The PF obviously wanted to bleed off some of the incredible VS of the airplane (and did so: 7000 to 700 ft./ min.). Why were they climbing so fast? I would say, because the PF inadvertendly induced a little nose up pitch, when correcting the right roll (02:10:05). Used to AP flying when at night and/or IMC it is not so easy to fly a clean straight line on instruments by hand. PLUS the startle of the AP+AThr disengage and the Wx-induced stress.

The stall warning in that phase must have been triggered by the erroneous airspeed breakdown. The pilots dealt with that by doing NOTHING (= nothing wrong). No need to.

Shortly before 02:10:51 they were nearly fine (but probably at their mental limits): 37500 fts and climbing with 700 fts/min with an AOA of 4° -- no trouble, but now speed down to around 215kts. That means stall and I think that is the moment when they lost the plane (first mentally, shortly after actually).

This time they didn't question the warning (by plausibility check), they simply followed procedures, they were behind their plane -- and flew into the deep stall. When the Captain entered the cockpit again; they were back down to 35000 and in the 'no-airspeed'-zone again.

Then, the second ND-input-phase (02:12:17), which could have changed everything. But, due to the lack of situational overview, at the next stall warning signal, they followed procedures again -- and threw their last chance away.

The PF said: 'Go ahead, You have control'. The wording is clearly NOT a confirmation, but a request: For me proof of the PF giving up. The procedure he (and two other pilots too!) were trained for doesn't work out. The end is known.

And there I am again: Do we overtrain pilots, do we encourage them to stop thinking and only follow procedures? There will always at some time arise a situation, where there is no procedure to be followed, because the situation is new, where common (flying-) sense is necessary and MAY save lives.

And there's my point again: Back to Basics!

ST27
29th May 2011, 21:54
Again, if PF had not made himself aware of Law change, and was functionally still in Normal, these inputs would not do harm. (Roll left, full aft stick).
Dropping a/p does not command degradation out of Normal Law. Could he have been that far behind? It takes AD disagrees to autoselect ALTLAW. So at what point were they aware of AD disagree , and how long after that before they acclimated there 'get'/'got' to new parameters?

From the report:

"2 h 10 min 05 , the autopilot then auto-thrust disengaged and the PF said "I have the controls"."

"At 2 h 10 min 16, the PNF said "so, we’ve lost the speeds" then "alternate law […]"."

So the PF should have been aware of the change within seconds.

There is no indication in the report of any other input recognized by the PF, other than putting the nose down as the stall warning sounded the first times.

ST27
29th May 2011, 22:00
It's a pity they got it wrong. When in confused state, one would try everything to save the situation. They must have thought stick aft at full thrust was working since the stall warning actually stopped blaring. The thing they couldn't resolve was why were they still descending at a rapid rate? That's when one of them pushed the stick forward, which unfortunately re-trigger the stall warning. So they pulled the stick back to silence the horn, and the action did silence it. And all the while, they didn't have a valid 'speedometer'...

It's not clear that the stall warning stopped as they descended. All the report says is that it started up again as the speed increased, not that it later shut off. We will have to see the final report to see for sure.

The ASI only were out for a matter of 60 seconds, according to the report, so they had valid indications for the last 2 1/2 minutes of flight, though they may not have recognized it or trusted it.

shogan1977
29th May 2011, 22:05
From SLF perspective it would be so much easier to swallow 'human error' as sole/major factor. That means when one flies over the ocean in the dark we can reassure ourselves with the thought that the pilots of this plane won't make the same mistake because... they're smarter/more experienced/not arrogant/not French/will have learned from AF447....

But reading all these posts two things stand out for me:

- Yes, clearly this accident COULD have been avoided, if the right action had been taken BUT who is to say any of you pilots would do the right thing?

- If the stall warning is (a) intermittent and (b) alarming when you do the right thing and silent when you do the wrong thing, it is human nature to be confused - question your actions, especially under stress.

That combined with the statements in this discussion by professional pilots that express arrogance, defensiveness, fear/"there but for..."/lack of trust in aircraft/technology... makes this SLF question the very people in the front seat who we depend on to get us there safely; the training provided by airlines and modern cockpit design.

Not a happy place to be :ugh:

ST27
29th May 2011, 22:08
Why he pulled nose-up is a mystery. Maybe he thought the 2 brief stall warnings were false, maybe he wanted to try and climb above the icing or the turbulence. However he did not have reliable airspeed indication in these moments, to attempt this.

As I read the report, it appears that the stall warnings were as a result of him pulling the nose up, not what caused him to the pull-up

Could he have felt the floor fall out from under him as a result of turbulence, and as a reflex reaction thought he needed to pull the nose up to maintain altitude?

crippen
29th May 2011, 22:14
Purely as a SLF,what would this 'ride' to 38,000 ft feel like? Climbing,but slowing rapidly. Floating,climbing or falling? Is this what deceived them?

gums
29th May 2011, 22:15
He was truly humbled and conceded that there were combinations of failures that are almost impossible to handled when one is caught unaware with not much time on one's side.

So, sky gods hold your peace. Thank your lucky stars that it did not happened to you. Hope that the manufacturers come up with equipments without all those design flaws; get the designers to think like average sensible pilots, not anal retentive hardnose savants who think that handling an inflight emergency is as easy as having brainstorming piss up in some soothing sequestered karaoke joint.Guess I am using up all my "attaboys" today, but great view/philosophy, Admiral.

I'll simply stand by my own experiences and reactions to the malfunctions that "could never happen".

"Luck is when preparation meets opportunity".

So the LEF assymetry detection and brakes didn't work. Doggone LEF folded up when the drive tube disconnected from the drive motor.. Could never happen, and max delta right to left would only be 6 degrees. WRONG!!!

http://i120.photobucket.com/albums/o196/gatlingums/rightwing.jpg

The next guy with the problem had to eject.

As I have iterated, the FBW system saved me from an ejection and I managed to get the thing back on the ground for the picture.

later, as I am about to join Amos and his opinions of the discussion. I only hang around to provide anecdotal evidence and some " academic" crapola to help folks understand the FBW systems. I'll let the second-guessing about pilot/crew reactions to others.

Ricky Billy Pearse
29th May 2011, 22:18
So, sky gods hold your peace. Thank your lucky stars that it did not happened to you. Hope that the manufacturers come up with equipments without all those design flaws; get the designers to think like average sensible pilots

AYE AYE, Admiral. It would have probably dumbfounded me too and I am mighty glad IT DID NOT HAPPENED TO ME.

Having said that, I also agree with the assertion that they AF447 crew SHOULD HAVE NEVER GOTTEN THEMSELVES into that situation. Avoid ITCZ type weather like plague, never try to outclimb CBs.

Avoiding situations that calls for superior skills is the key to survival. This strategy will never get one into the headlines as heroes saving a crippled plane but keeps one flying smoothly and cooly into quiet retirement.

milesobrien
29th May 2011, 22:24
So how would you grade mainstream media coverage of this crash - and aviation in general? Examples (good and bad) would be appreciated. Since I anticipate a lot of criticism, how can we make it better? How does social networking, blogging and other wholesale changes in the way news is shared change the dynamic? Why are so many pilots loathe to speak with an MSM reporter? Discuss...

bearfoil
29th May 2011, 22:34
One generally can pick out a character flaw in others that he himself owns.

MOF, It is almost exclusively the case.

The time may be near to lose this "Sky God" mentality, and its corollary, the "Sky God" by critical proxy.

There never should have been an Ivory tower, least of all these days. No one is well served by ignorance of the fundamentals, nor does it further the industry to pretend "complexity" to keep hidden the foibles that we all are entitled to know. I've known a few "Four Bars" that were guilty of visiting that many watering holes prior to push.

It is a human endeavour, and to pretend that the BEA are engaged in some hideously complicated endeavour keeps all of us in thrall to the sheepherders.

Knowledge is power, and refusing to embrace it leaves the power to others.

that's two on ignore.

Ask21
29th May 2011, 23:05
In another life as a checker, after completing the sim check of a super ace to a very high standards we used the remaining time to conduct some extra excercises on really unusual attitudes with combinations of other failures...the plane went belly up, ace or no ace. We repeated it twice, same results. 2 years later, another sim check and super ace asked for another go at that exercise...he managed to save the plane but barely. He admitted he thought long and hard about it coming out with all the possible solutions in his head before the session. He was truly humbled and conceded that there were combinations of failures that are almost impossible to handled when one is caught unaware with not much time on one's side.

- NOW - thats the kind of simulator training all pilots should have before they're alowed to become captains. I'm impressed by that ace that came up in his mind with a theoretical solution - and managed to "do the impossible".

The publix / PAX expects (perhaps naively?) the captains to be able to handle the plane from all kind of situations - even it it takes unusual flight maneuvers - like useing the rudder to drop a wing during stall-recovery. The issue is not only be able to handle the initial failure /situation- so to stabilize flight without further or minimal harm- but also to practice sim-scenarioes where everything is suddenly - totaly critical - catastrohpic - Like the the situation the captain found himself in when returning to the cockpit.

Just for curiosity - how many -sim hours are required to become a captain? How many of them will be spent training actual catastrophic scenarios? (not only avoidance of them).

The issue is not only what to do correctly at a high altitude stall warning - but what to do when the things you have done so far has actually made the situation worse - eg the situation between 30000 and ground in this flight (the fully developed flat-stall variant: 40deg AoA - 15 deg pitch - 10000f/min sinkrate)).

It would also be interesting to know at what altitude it was "to late to recover" this sad situation. Assuming you still had pitch authority - or assuming not sufficient pitch authority) - any guesses - 6000 feet?

thermostat
29th May 2011, 23:20
with a plugged pitot, in a updraft (climb) the IAS would increase. If the increase was shown on the ASI, the tendency would be to pull back to reduce the speed, perhaps?? It must have been very confusing for them during those last minutes.

Flight Safety
29th May 2011, 23:20
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.

If you don't trust the PDF and all the magic, isn't this what the ISIS is for? Also, what were the engines doing at IDLE only 70 seconds or so after they commanded TOGA power? They must have really been confused.

misd-agin
29th May 2011, 23:20
Ask21 - Just for curiosity - how many -sim hours are required to become a captain? How many of them will be spent training actual catastrophic scenarios? (not only avoidance of them).

Upgrade program had 24 hrs of sims. Normal emergencies(fire, engine failures, brake problems, flap problems, bleed problems, etc, etc). Not sure what you mean by "catastrophic". Some 'extra' stuff, nil braking, extra low vis, etc. Line experience was 21:04 and 11 flights.

For my company I was a relatively inexperienced upgrade. At time of upgrade I had 7350 hrs TT, 200 hrs sim, 900 hrs in type, 3300 hrs w/company, 6.5 yrs with the company. Upgrade was my third type rating at the company.

Minimum upgrade experience now is probably 12,000 - 15,000 hrs TT. So when some people say "experienced" others think "maybe not that much". :ok:

canyonlight
29th May 2011, 23:24
Mr. O'brien, your question is a good one. Given the very good quality of the PBS special NOVA on this accident, I'd have to rate the coverage as high. But I'll withhold judgement until I see a follow up program. I believe that the factors that fully explain this accident are complex and varied. A media presentation that could identify and explain those factors would be most useful. Things like automation, aircrew training, corporate cultures, and the like probably all had a role in this accident. A media analysis that identified all these factors, their interrelationships, and how helpful changes could be made would be excellent. Thanks for your great work in this area.

Raygunner
29th May 2011, 23:43
I've been reading this section of the forum over the last few hours with great interest.

What strikes me as a defining moment is when the nose was pushed down and the stall warning was reactivated. This apparently caused the PF to pull the nose back up, sealing the fate of everyone aboard.

One major problem, as I read it, was the stall alarm came on as the plane slowed and then shut off as the airspeed dropped below a minimum threshold. Then the PF pushed the nose down which brought the airspeed back up, causing the stall warning to appear again. In the confusion maybe everyone had it backwards - that the plane was OUT of stall when the alarm first stopped, and was BACK in stall the second time. This might have caused the startled PF to pull the nose back up in a WTF moment. There is no "begin stall warning" or "end stall warning" sound effect, correct?

If this is the case, I think a simple doppler-type sound could be superimposed on the warning as a "directional" enhancement. As you go INTO a stall, a high frequency sound slowly drops to a lower frequency (tied to airspeed/pitch etc) and could be heard under the stall alarm. When the airspeed drops to the minimum threshold the warning stops as it did. As the plane regains airspeed and the stall warning reactivates, the doppler sound resumes, going from a low to high frequency until the craft recovers from the stall and the alarm shuts off. The fact is the pilot now has a direction tied to the stall, where he/she is in the stall, and the progress being made to recover from the stall.

The doppler sound would be dynamic, that is it would be a real-time sound that would reflect actual conditions. If the plane touched on stall conditions and dipped slightly lower before recovering, you would hear the high freq drop slightly, then rise back up until the stall alarm stopped.

With this aural clue, there would be no mistaking where the stall is occurring, and if you are going deep into one or recovering from a stall below the alarm's threshold.

I apologize in advance if I offend anyone here with my ignorance - I'm a platinum flyer and just self-loading-cargo, that's all.

I appreciate all that I read here - you good folks are just trying to understand this and I thank you for caring enough to try and figure this out. It's comforting to me and for all of the other "pax" reading this :D

woodyspooney
29th May 2011, 23:45
Major Pacific Rim carriers are looking for skippers with 500 PIC hours on type for the big jets! So they have hordes of " adventurers " knocking on their doors with " parker penned " hours or from " airline pilot mills " that have sprouted up in recent years. Minimum sim training, mimimum sectors on line training. Lo and behold you have el capitanos with 4 shiny bars on big shiny jets.

I had been augment crew to some of these newbies and some have no clue as to how to operate a modern weather radar properly! Flying through the equator through ITCZs invariably becomes a free roller coaster ride.

Avoid, avoid, avoid. Not detracting Sully from his superb handing in the Hudson River thingy, it would have been sublimely great had he been able to avoid hitting the birdies. It would have been no headlines if the Air Transat A330 superglider crew nipped the fuel leak in the bud and diverted safely without the drama. Then again, they live to receive accolades.

These AF447 crew unfortunately did not live. Had they made it through and nursed their crippled plane ( I would suspect some damage after the hair raising plunge ) to a landing somewhere they would have been amply rewarded with publicity and possibly some French aeronautical awards.

To all out there, if you think your airlines have trained their pilots sufficiently for the most complex failures you are sadly mistaken or kidding yourselves. In the corporate, commercial environment accidents like these are at best " acceptable " damage ( one in 10 million chance, or one in 100 million chance ratinale ). Anything you hear about safety from airline higher ups are nothing but posturing, outright lies and utter baloney.

thermostat
29th May 2011, 23:54
Ricky Billy

You are so right. Thank you for those comments, my sentiments exactly.
Flying through CBs at high altitude, near the "coffin corner" at night is simply crazy. That's why we have weather radar.

Capn Bloggs
30th May 2011, 00:03
Flying through CBs at high altitude, near the "coffin corner" at night is simply crazy. That's why we have weather radar.
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.

fdr
30th May 2011, 00:09
A GPS cannot do this.

It only reports how fast the plane is actually moving, which says nothing directly about how much airflow the pilot has to work with. In addition, it figures in wind effects, which also have no direct usefulness in controlling the plane.

Pop quiz:

You are at 35,000 feet. The GPS says you are traveling at 400 kts due north over the ground, decreasing at 1 kt per second. There is a 60-kt jet stream blowing from the southwest (217°). Your stall speed (no flaps) would be 167 kts INDICATED, but your airspeed indicator isn't working. Your heading is 356°. Barometric pressure is 29.75 (but your altimeter is set to 29.92 as in all flights above 18,000 feet.) The air outside is -42° C.

Not absolutely true.

for a given configuration, GPS(s) systems can be used as a sole source to give attitude and performance data, including AoA. (20 years ago... in experimental testing, nowdays my cat has a GPS...) In fact they can even be used to track wing bending/fuselage torsion etc... if you use the carrier wave rather than only the signal directly.

At least on the B777 TBC came out with a simple switch, the FPV which just gives the derived FP, and is a ready indicator of AoA for a... er..."crosscheck". (S&L it is a great analogue of AoA, but in high bank angles it takes a little more thought to determine the AoA from the display). The underlying source is hybrid AoA/ADC through the ADIRU, which of course removes the opportunity for redundancy.... maybe next time.

The question is how conditions that were encountered by a first world operator, operating state of the art technology, all generally conforming with the structured, bloated,bureaucratic, costly guidelines of EASA/JAA defeated all the safety protocols so spectacularly.

AF447 crew response is not isolated, and that should cause concern for those passengers that consider dummying down aerospace to a commodity product as packaged and sold by M.O.L., Safety is expensive, but the public pocket has driven the industry to the point where it is argued that a MPPL is a good thing, that pilots are operators not pilots.

Next time you fly, look out the window, that thing out there is a wing. XBox, MS FS etc don't usually employ such things. Using a computer simulation, normally you don't end up dead, as the m.v^2's are generally of a much low order of magnitude. There is nothing trivial about the kinetics of an aluminium tube stuffed with assorted people moving in 3d space (4d... avoids MAC's) at high speeds, with lots of hydrocarbons, yet, as indicated elsewhere we are happy to pay the taxi driver more for 15 minutes, or the terminal company more for 1:00 hr of parking than we pay for the opportunity to dance around the sky.

As Feynman said in '86,

"For a successful technology, reality must take precedence over public relations, for nature cannot be fooled."



PS:

the impact of auto trim from erroneous speed information, and the control law reversion needing the cognitive engagement of the crew to the dynamics of the situation in a highly stressful sudden onset event, that is additionally time critical is much easier to quarterback later, with the benefit/certainty of hindsight. (AI products have had numerous events and disasters where the trim system has resulted in an out of trim condition). I do not criticise the crew, I criticise the bureaucratic system and public apathy that results in conditions precedent where lives are needlessly lost in the pursuit of cheap travel. Pay in cash or blood, simple choices.

Graybeard
30th May 2011, 00:41
Glad to see you're still/back with us Mr. Obrien. I enjoyed the CNN bit you did with your plane a couple of months ago. While I don't follow every MSM report, and turn off Fox/WSJ, I've tended to find Bloomberg more rational than most. Here's what I posted on the Techlog back on April 24:
--------
Just last night I got around to watching PBS NOVA "Crash of Flight 447," which aired on 20 Feb. There seems to have been considerable discussion of it, judging by snippets, but there must have been a lot of it at the time, (now page 138 of prior thread) censored by the mods, as there are incomplete references and very few posts from about then. That is disturbing.

Nova tried to explain the events leading up to the crash. I'll address only the Wx radar here.

Their expert, from NCAR part of NOAA, said the Wx radar on AF447 had only 50 mile range. Strike one. It's 320 miles, if the storm is dense enough to matter.

Nova showed a small/medium sized cell in the plane's track toward the major line of storm. Nova said the small cell would obscure the radar view of the major storm, causing them to stumble into it.

Poppycock/BS/Hogwash! The Wx radar on 447 returns were calibrated for rainfall intensity. When the intensity of return is high, an algorithm called "Path Attenuation Compensation" kicks in to assure calibrated display. When the storm is too intense for penetration without reserve to see the full picture of the "storm behind the storm," the Wx radar puts up a yellow band, called PAC Alert, at the outer range ring of the display.

I have great respect for Public Broadcasting in the US, but this program failed miserably. I wonder if major sponsor, billionaire David H. Koch, didn't have too much editorial input?
--------

PS: Why did they choose to interview a radar guy unfamiliar with that specific airborne Wx radar? The least the guy could have done would be to study the Pilot's Guide in NCAR's own C-130, which is operationally just like the WX radar that was in AF447.

Was this pgm just a re-badge of the BBC pgm from last summer, or a real update?

Mimpe
30th May 2011, 01:00
Wouldnt it be additionaly tragic if the stall warning reactivated as a result of the correct application to nose down pitch, thus further confusing the crew.

Probable unrecognised spatial disorientation ( somatogravic decelleration illusion)

bubbers44
30th May 2011, 01:13
FS, the only way I can see them going to idle is they got a false overspeed warning because they climbed 3,000 ft with blocked pitot tubes which would give an overspeed warning with static pressure reducing in the climb. The 32 year old in the right seat, PF, had less than 3,000 hrs and 800 in type, probably 798 hrs monitoring the autopilot so he probably didn't stand much of a chance of hand flying it at night with no airspeed in moderate turbulence. The full up control in a stall is an Airbus thing I guess. Nobody else does that. Apparently the computer will protect you in normal law but they went to alternate law so from what I hear you are not stall protected.

Magic airplanes like Airbus take the pilot out of the loop and make them monitors and eventually they will lose their basic flying skills if they ever had them. This pilot was probably for the first time in his life hand flying an Airbus 330 in unfavorable conditions he couldn't handle.

learner001
30th May 2011, 01:21
From pointers to drums... From dynamics to numbers...

Tiny observations large outcome...

When I started flying ‘digital’ I missed and preferred the ‘old’ familiar dynamic moving pointers on the Airspeed indicators and Altimeters, rather than the relatively ‘dumb’ moving number-tapes and/or drums on the flight displays.

And my ‘emotion’ is not limited to Airspeed indicators and Altimeters only.

Of course, as with all sort of changes, I was told that I “just have to get used to it!”

OK... Fair enough... But, although I am getting more and more used to ‘flying digital’ by now, on occasion, I really sense the lack of instant dynamic ‘speed and altitude situational awareness’ that the ‘old’ analogue Airspeed indicators and Altimeters with their moving pointers will give us more or less instantly.

Looking at the tapes I have to figure out: Are the changes going up or down? Moving Fast or slow? Is it an increase or a decrease? What’s the trend? Things, that I would instantly be aware of with the analogue indicators. With digital indicators, however, I need more of my brain capacity to ‘translate’ the sheer changing of numbers on the rolling tapes (or drums) into dynamics.

Oh, yes... We’ve got the ‘speed trend arrow’ to sort the speed thing out... Haven’t we... But, then again, isn’t this turning the things upside down?

In every new aeroplane that our company receives, even the ‘last resort’ analogue standby instruments have been replaced by a single digital display.

Man tries a lot of things to improve safety. On the other hand, in my opinion, these efforts are broken down again, unnoticed.


As for hindsight typing behind the computer:

Most of our daily flying ends at a couple of hundred feet going out and starts again at a couple of hundred feet coming in... Almost every flight we are being flown, mostly by the comfort of automation, very near to the ‘coffin corner’... The ‘gap’ being smaller one time than the other. I wonder how many of us really actively realise this...

At high altitude in the very thin air, especially in turbulence at night, a cockpit can turn into a relative ‘hell’ very abruptly if the Autopilot kicks off... (LOL most probably from many in here...) Controls will be very sloppy in conventional aircraft. In FBW aircraft this will be even more (un) noticeable, as there is different or no direct feedback.
In both cases, while you’re shaking, you need to handle the controls like being a Swiss watch maker. And you are now manually manoeuvring within this tiny confined little gap... If you’re lucky you may have done it may be a couple of times. Even ‘minutes’ would do a great deal of benefit already... But it is something we hardly actually ever do...!

Are we stupid, then? We train constantly for all sorts of situations... Or could here be a training deficiency? If you have/were never trained in hand flying close to the ‘edges’ of an envelope (or even outside an envelope), or if you have never actually been hand flying close to the ‘outside’ of an envelope, chances are that you won’t even notice that you’re going out... Whilst thinking you’re ‘hanging in there’... And so far, so good...

How much ‘flight time’ were our unfortunate colleagues granted to log in their logbooks on actual hand flying the plane in that tiny little gap, before they all of a sudden were forced and committed to do so in a very, very narrow gap. Whilst probably shaking, vibrating and being bombarded with all sorts of alarms going off...

So, whilst trying to analyse, I have learnt to always remain respectful and very humble and do a great deal of effort to see the whole picture...

jcjeant
30th May 2011, 01:42
Hi,

Shogan 1977

From SLF perspective it would be so much easier to swallow 'human error' as sole/major factor. That means when one flies over the ocean in the dark we can reassure ourselves with the thought that the pilots of this plane won't make the same mistake because... they're smarter/more experienced/not arrogant/not French/will have learned from AF447....

But reading all these posts two things stand out for me:

- Yes, clearly this accident COULD have been avoided, if the right action had been taken BUT who is to say any of you pilots would do the right thing?

- If the stall warning is (a) intermittent and (b) alarming when you do the right thing and silent when you do the wrong thing, it is human nature to be confused - question your actions, especially under stress.

That combined with the statements in this discussion by professional pilots that express arrogance, defensiveness, fear/"there but for..."/lack of trust in aircraft/technology... makes this SLF question the very people in the front seat who we depend on to get us there safely; the training provided by airlines and modern cockpit design.

Not a happy place to beThe statistics show that air travel is the safest
The statistics also show that 80 % of the accidents are the result of pilot error
So when you take place in a plane .. you know that if thing go wrong .. you have 80 % to go not go out of a survivable accident
Or at least .. 20% of the pilots are good in abnormal situations
That's the beauty of the statistics
Think about ........

misd-agin
30th May 2011, 01:54
Learner 001 - I've flown round dials to full glass. Obviously FMC's and EGPWS are light years beyond the 727 for situational awareness. 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.

Al Goreng
30th May 2011, 02:00
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.

Sigh! Let's not be anal or pedantic. Supercooled water, icing at over 35000 feet yadda yadda yadda. If they were not in a CB, over a CB then it was somewhere close to a CB where the effects of a CB were pretty evident.

I concur with woody; I have seen 13000 hour veterans with only 600 hours on type happily flying in vicinity of odd shaped hooked weather radar returns simply because they had plotted a course in the clear a few miles downwind of such a return. Oh, those wonders who were produced fast track through jade cargo, air china cargo, jal express, polar etc then go around blaming everything else for the bone rattling shake they get.

Me Myself
30th May 2011, 02:03
Tell me one thing :
Loss of airspeed indication happened several if not a lot of times before without a loss of aircraft. Why this time ?
The Air Caraïbe incident wasn't exactly a walk in the park, nor the Northwest one.
I doubt AF will ever bother to find this crew and ask them how they did it. After all, it's all in a very comprehensive paper they wrote that nobdy bothered reading until......It then almost turned to the New York Times best seller.

Training ? A lot has been said about this. Every aircraft I trained on I had to go through the Loss of Airspeed syllabus.
Awareness is what it's about. It's been said above by an Aussie 330 pilot who's airline had several incidents of the same kind before 447 ever happened.
1/ Keeps out of the weather
2/ Memorizes pitch and thrust
3/ Briefs F/O and S/O
4/.....could have been 1/ Stays with his bumm in his seat when bad weather forecasted because he knows this is exactly the kind of spot you are likely to lose your speed indication.
And this Ladies and Gents gives you................Qantas.

These guys get the same kind of training major airlines get and yet everything they've had to deal with in the last 3 years was totally out of the ordinary and they dealt with it superbly.
So why is that ? I would say compagny culture, personal ethic and discipline added to a long history of phenomenal track record.

IcePack
30th May 2011, 02:06
Interesting stall characteristic most a/c pitch decreases when fully stalled.

ST27
30th May 2011, 02:08
I would say company culture, personal ethic and discipline added to a long history of phenomenal track record.

You forgot to include a good dose of luck in that list.

learner001
30th May 2011, 02:15
misd-agin: 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.

And the (just earlier) seen image of the position of the pointers is still with me, when I look elsewhere... With 'numbers' you can not do that...

Kind regards, learner . . .;)

bearfoil
30th May 2011, 02:16
ice pack

"...Interesting stall characteristic most a/c pitch decreases when fully stalled..."

cg?

thermostat
30th May 2011, 02:26
Capt Bloggs

I take it you haven't seen the satellite photo with the flight path superimposed on It. It shows the extent of the storm system with the route going through the cells. Can you explain to us all just why the A330 went out of control after entering the system? Why did the F/O make a call to the F/As advising them of turbulence ? There are none so blind as those who will not see. Why would the plane go out of control if it hadn't been close to the coffin corner in turbulence? Why would all the ASIs stop working simultaneously and all those warnings begin (some of them false) if there was no supercooled water in the CBs to cause icing of the pitots? Please answer these questions for us.

philipat
30th May 2011, 02:26
I'm not a pilot but just looking logically at the known facts, when descending at 10K fpm at TOGA with the pitch and attitude data available, AND Stall warnings fed from the latter, how could they conclude other than that they were already in a stall? (If it walks like duck......)Were they trying to "Pitch and Power" through the weather with the lack of airspeed data when already in a stall?

Graybeard
30th May 2011, 02:38
+/- 0-6K fpm is the typical VSI range on the steam gauges. What is max displayed on AI EFIS? Could the VSI display have flagged or just disappeared, due to out of limit input of 10K and more?

Just asking.

Denise Moore
30th May 2011, 02:45
Correct me if my question makes no sense. I noticed in the BEA report that is says the PF mostly pushed up. But it did show that he also tried pushing down. The plane was responsive, apparently, so shouldn't that have improved the situation.

It would appear that the PF thought pushing down wasn't improving the situation. Or he wouldn't have gone back to pushing up. Shouldn't pushing down have improved the situation? And shouldn't something have told the PF that it was improving the situation?

thermostat
30th May 2011, 02:46
Graybeard,

short answer is yes. If the needle was beyond 6,000 fpm they may not have realized how fast they were descending.

Denise Moore
30th May 2011, 03:06
I've noticed different explanations about stall warnings here. So I wonder --- I don't know --- if that's a serious cause of confusion.

One place said the stall warning sounds once and then stops even though the plane is still stalled.

One place I saw it said when the stall ends, the stall warning repeats unchanged. (NOT saying "Stall ended".)

If all that is so, what if some part of the flight computer detects a new/second stall before the first stall ends?

If the warnings are the same, the pilot has to keep count of whether the number of warnings is odd or even.

Another post referred to stall warnings becoming continuous. But that's not how the other posts describe it.

RobertS975
30th May 2011, 03:27
Weeks back, someone posted a website which showed the tracks of the many flights headed across the South Atlantic that night and every one of them deviated as they came through heavy weather EXCEPT for AF447. It shot straight through into the brightest red weather without so much as the slightest turn.

I can't get the link I have top work but the plot was from a bea.com trajectory plot sometime around April 6th.

Denise Moore
30th May 2011, 03:28
"Why the .... did the stupid automation silence the stall horn ? "A great question. The systems silenced it because the IAS fell below 60 kts for a time. This caused the FWC (Flight Warning Computer) to silence the STALL warning."

From reading all the various posts, I conclude this is the ultimate cause of the crash because it misled the pilots.

Wouldn't a quick check by the flight computer have shown the plane was not on the runway but in the air? That should have been done.

CONF iture
30th May 2011, 03:29
I take it you haven't seen the satellite photo with the flight path superimposed on It. It shows the extent of the storm system with the route going through the cells. Can you explain to us all just why the A330 went out of control after entering the system? Why did the F/O make a call to the F/As advising them of turbulence ? There are none so blind as those who will not see. Why would the plane go out of control if it hadn't been close to the coffin corner in turbulence? Why would all the ASIs stop working simultaneously and all those warnings begin (some of them false) if there was no supercooled water in the CBs to cause icing of the pitots? Please answer these questions for us.
A satellite photo is not what a crew will see on his wxr radar screen. The screen will show where the cells are and the crew will deviate from them.

In the meantime it is good airmanship to advise the back crew that we may well still encounter some turbulence.

AF447 was nowhere close to the coffin corner. According to the QRH table it was actually around 1500ft below the optimum.

The issue is not supercooled water but more probably ice crystals.

Woof etc
30th May 2011, 03:34
Dart your eyes rapidly in a random fashion through the following list and call out the COLOUR of the word:


GREEN



BLUE



RED



ORANGE



YELLOW



I think this is a good example of cognitive dissonance, and illustrates that the human brain is not always that great at resolving conflicting information. Try the same exercise at night in turbulence when you are tired and jetlagged with a plethora of warnings and aurals going off - there but for the grace....

Flight Safety
30th May 2011, 03:36
Maintaining the previous configuration, should maintain the airspeed.

Seems to me if you're at cruise altitude and speed on both AP and AT, then suddenly you loose IAS and both the AP and AT disconnect, you might realize that you're already in the correct configuration at that point. The AT disconnect will leave the engines at the correct power setting they were at, so just maintain wings level, maintain the same altitude, and maintain heading. This would probably work even with moderate ice accumulation (since the AP and AT would have already made this configuration flyable). If the AP disconnect causes an airframe movement, correct it back to the same altitude, heading, and wings level. Once the AP disconnect and hand flying is stabilized, then smoothly transition to the pitch/power settings. Even if turbulence causes you to continually focus on maintaining altitude, heading and wings level, thus preventing you from transitioning to the memorized pitch/power settings, you should still be in pretty good shape while you sort it out, by maintaining the previous configuration.

All of the above assumes of course that you can hand fly the airplane at high altitude. Perhaps the PF did not have a good feel for hand flying the A330 at altitude (maybe why he gave the controls up later?), especially with moderate turbulence taking place.

The sad thing is, if the PF had just stayed put after the AP and AT disconnected, he would have gotten IAS back in about a minute, and this would have been an incident report rather than an accident. However, then there would have been steps and procedures for systems recovery after IAS return, which would have been a whole other set of problems.

Ace Springbok
30th May 2011, 03:45
I fail to understand why the stall warning had to deactivate at below 60kts. Wasn't there a ground mode/air mode logic on this wonder bus?

Denise Moore
30th May 2011, 03:59
I saw a reference in one post to a "panicked Captain shouting commands".

Maybe I missed it, but the transcript I read didn't mention the Captain saying anything. From which I assumed he thought he didn't have any good instructions to give the PF or PNF coopilots.

taildrag
30th May 2011, 04:42
When the Airbus A-320 was still in planning stages, I remember a presentation in a conference on aviation psychology relating all the combinations of circumstances software code writers had to consider, such as what warnings to inhibit on takeoff when they could be a nuisance, etc., which presentations were appropriate and when, and which might not be.

The speaker said there were many combinations of events the software could not anticipate, that it would be impossible to write software for unforeseen events, and that doubtless the software itself would probably cause some problems.

Add to that the reticence of some pilot unions (was one Air France's?) about the "fly by wire" concept at the outset, with no mechanical controls whatsoever,and it seems this recent nightmare situation is an example of expressed fears of just such unknowns.

All this speculation is premature. As many have said, it seems really more a matter of "there but for the grace..." etc.

It all makes the QANTAS A-380's crew's performance, augmented by the extra pilots who were all busy, just that much more remarkable.:eek:

stilton
30th May 2011, 06:33
If there is one piece of unambiguous information this crew could have used to save their lives it is a display of AOA.


It is nothing short of negligent that this information is easily read on the flight recorder after the crash but was not accessible to the crew.


AOA information is available on every jet transport, it should be displayed constantly, at least on each EADI and additionally on a dedicated, independently powered standby instrument.

Final 3 Greens
30th May 2011, 06:36
I whose screwed up mind can a life be worth more or less depending on how long the descent was and when in that process they all died?

The legal community, who make the awards, see

64 New York University Law Review 1989 Final Moments: Damages for Pain and Suffering Prior to Death (http://heinonline.org/HOL/LandingPage?collection=journals&handle=hein.journals/nylr64&div=17&id=&page=)

You will see in the reference that the extra damages are intended to have a deterrent effect.

I'm not a lawyer, so please don't shoot the messenger.

DouglasFlyer
30th May 2011, 06:42
@Greybeard
What is max displayed on AI EFIS?
We didn't have ISIS on the A332 but on the A333 and the A343. I don't know if AF had the same ISIS, but ours only displayed the following datas:

The ISIS system displays the following information:
- Attitude
- Airspeed and mach
- Altitude
- Barometric pressure
- LS function
- Bugs
(OM B A343 - Vol 1 / OM B A333 - Vol 1)

Therefore no VS indication on the ISIS.

SoaringTheSkies
30th May 2011, 06:54
It is nothing short of negligent that this information is easily read on the flight recorder after the crash but was not accessible to the crew.

That's what I said earlier. I read somewhere that AoA display is/was an option on certain Boeing products, not sure about Airbus. It would be sickening to know that, in those dire moments, the single most important parameter, while present and available to the system, wasn't displayed because the customer had't ordered the software feature to do so.

Razoray
30th May 2011, 07:20
It would be sickening to know that, in those dire moments, the single most important parameter, while present and available to the system, wasn't displayed because the customer had't ordered the software feature to do so.
IMHO, one of the outcomes/goals of the investigation, and a focus of this thread should be to make it mandatory for the AoA to be on all commercial aircraft...no exceptions.

nitpicker330
30th May 2011, 07:23
They didn't need an AOA display on their PFD to fly the Aircraft.

I'm getting sick of repeating myself but here goes again.

This is not a new event

Let me say it again

This is not a new event

It's happened before and ALL OPERATORS HAVE PUBLISHED PROCEDURES FROM AIRBUS TO COPE WITH THE PROBLEM OF UNRELIABLE AIRSPEED.
These procedures detail what you can expect to hear and see during the event. They detail explicitly what to do.

Most competent Airline Pilots would have read about this problem, been shown the problem in the Simulator and hopefully bothered to have a think about what they would do if faced by the same event. I know I've put a lot of thought into it and so should have the AF crew.



Ok, so now we are clear.

cats_five
30th May 2011, 07:35
The Air Caraïbe incident wasn't exactly a walk in the park, nor the Northwest one.
I doubt AF will ever bother to find this crew and ask them how they did it.

I had no problem finding out something about this, including a memo by the flight safety officer.

Air Caraibes Atlantique memo details pitot icing incidents (http://www.flightglobal.com/articles/2009/06/11/327738/air-caraibes-atlantique-memo-details-pitot-icing-incidents.html)

An Air France air safety message to its pilots last November talks of six related incidents on A330/A340s resulting in incorrect airspeed indications, numerous warning messages, and sometimes configuration alerts.

It urges pilots to be vigilant at high altitude when icing and turbulence are encountered, and to fly the aircraft gently if they take manual control.


And the Air Caribes memo itself, which is in French:
Air Caraibes Airbus A330 memo (http://www.slideshare.net/Unusualattitude/air-caraibes-airbus-a330-memo)

SoaringTheSkies
30th May 2011, 07:36
Ok, so now we are clear.

oh, it's been clear before, no problem with that!

however, every indicator other than the AoA gives you secondary information with respect to a stall condition. In a dire situation like this with a tsunami of information, warning, system errors, failing systems, unreliable systems etc rolling over your head, it can be very hard to correctly interpret secondary information. Having the root cause shown to you would shortcut through the cognitive dissonance and help gain correct situational awareness.

nitpicker330
30th May 2011, 07:44
An experienced crew would know for their a/c:--

1/ what pitch attitude they must fly AND WHAT IS NOT NORMAL
2/ what thrust setting they must fly AND WHAT IS NOT NORMAL
3/ What noise levels constitute "normal" for their cruise speed
4/ That it is simply not possible to climb 3,000 feet at heavy weights at high altitude quickly ( 7000 fpm apparently ) without Stalling the damn plane
5/ That if they entered the area at a normal speed and power settings then all they had to do was keep the pitch attitude somewhere around 2 deg nose up ( lower wouldn't matter too much, but higher does ) and the thrust around 78 to 80% N1 and they would be ok.

6/ keep the wings level and BE SMOOTH ON THE SIDESTICK.

Pininstauld
30th May 2011, 07:46
1. A/c enters cloud with high concentration of super-cooled droplets.
2. Faulty pitot ices over on PF side "freezing" dynamic pressure sent to ADC.
3. Sudden convective event induces a climb reducing static pressure to ADC.
4. PF responds to perceived Mmo excedence with stick back.
5. Static pressure reduces causing airspeed increase.
6. Auto-trim blindly complies with pilot input increasing nose up towards maximum.
7. Repeat steps 4 to 6 until stall....
8. Stall warning stops but comes back on if PF does the right thing.
9. Software has turned off auto trim with stab trim stuck 13 deg up.
10. Software has turned off the bird, just when it would has improved S.A.
11. Checkmate to the software....

In all error chains there's always a bit of man + a bit of machine. But once this kicked off, the man didn't really stand a chance, now did he?

jcjeant
30th May 2011, 07:47
Hi,

They didn't need an AOA display on their PFD to fly the Aircraft.I disagree ...
You can't be so affirmative.
Methink the AF447 case is enough to understand that some pilots or aircraft under certain condition need a AOA display.
So ... the solution is to go to the most safe side and have a AOA display
And also needed a stall alarm who sound with no interrupt when aircraft is in stall condition
Save lifes first .. with experienced or inexperienced pilot is a noble task
Foolproof .. as always.

Was in 2006
By Joelle Barthe
Flight Operations Engineer

Quote:
6 Conclusion
An unreliable speed situatio may be difficult to identify, due to the multiple scenarios that can lead to it. Therefore, training is a key element: indeed the flight crew's ability to rapid detected the abnormal situation, and to correctely handle it, is cricial.
In case of any doubt, the pilot should apply the pitch/thrust memory items, and then refer to the QRH to safely fly the aircraft, and to positively determine the faulty source(s) before eliminating it (them).
In addition, to further assit the pilot in detecting the failure and safely fly the aircraft, Airbus has developed the BUSS, which provides a safe flying range indication.
Finaly, to reduze the probally of experiencing unreliable speed situations, on-ground actions, such as comprehensive maintenance and through pre-flight exterior inspection, should be stressed.

nitpicker330
30th May 2011, 07:50
well I think it reasonable to expect that this crew might have ignored that piece of information ( AOA display ) just like they ignored 3 fully serviceable BIG ATTITUDE INDICATORS right in front of their noses.

astonmartin
30th May 2011, 07:53
There is no AOA display in the A330.

nitpicker330
30th May 2011, 07:56
Yes we know that thanks.

Actually if you have time ( they didn't ) you can call up AOA in the CMC maintenance pages.

astonmartin
30th May 2011, 07:56
@ Pininstauld: This scenario doesn't work in alternate law...

BOAC
30th May 2011, 07:57
Absolutely with nitpcker. Until the BEA tell us WHY the aircraft was climbed so rapidly we are all 'groping in the dark'This scenario doesn't work in alternate law - which bit and why please?

wallybird7
30th May 2011, 07:57
TO ME IT IS WAY TOO EARLY TO SPECULATE ON A PROBABLE CAUSE BECAUSE ALL OF THESE DISCUSSIONS ARE BASED ON DATA THAT IS SELECTIVELY RELEASED. TOO MANY ISSUES ARE YET TO BE RESOLVED.

Pilot control versus Computer control. Flight into hazardous conditions. Simulator training. Pilot qualifications.

Too many questions. No conclusions.

Way too early for the public to be involved in hip-shot resolutions.

astonmartin
30th May 2011, 07:58
@nitpicker That would be the same as driving on the highway while looking down while shifting gear.

opherben
30th May 2011, 08:01
A side comment about AOA indication, valuable info for such operation:
a. It can be measured directly with a vane, but is subject to icing.
b. It can be calculated from INS measurements, generally it is the difference between flight path angle and fuselege pitch attitude.

Its absence was not a factor. A pilot can see the altitude dropping rapidly and the nose pointing up, which is sufficient information to deduct a very high AOA. A push of the sidestick forward would have been enough.

What to me is unacceptable, is an aircraft changing its response to my flight control inputs, due to some laws switching to and fro. In an ideal world it could be regarded advanced, but in the given circumstances it makes the pilot a deputy assistant to the autoflight system, as opposed to the pilot in command.

nitpicker330
30th May 2011, 08:02
So in Cruise or other low activity times am I not allowed to look down to my right and use the CMC display on the centre CDU? You might as well remove it then!!

Please re read my post, i did say in brackets that they wouldn't have had time to check it.

Grrr

shogan1977
30th May 2011, 08:06
'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)

HE was one of Air France's "company babies": a dashing 32-year-old junior pilot - and a keen amateur yachtsman - who had been qualified to fly the airline's ultra-sophisticated Airbus A330 jet for barely a year.

Yet despite his inexperience, Pierre-Cedric Bonin found himself responsible for the lives of 228 passengers and crew members on June 1, 2009, when the cockpit of his $190 million aircraft lit up with terrifying and contradictory alarm signals en route from Rio de Janeiro to Paris.

Robert [sitting in the RH seat] shouted with increasing desperation for the captain... Is this based on info officially provided by the BEA?

The question being asked in the industry is why, given that there was a 50,000ft thunderstorm near the plane's flight path, the youngest of the three pilots, with the least flying time, was at the controls.

“It seems as though they were just clueless,” says Mike Doerr, a former Airbus A320 captain who charters private jets in California. “The response to the invalid speed data doesn't make any sense unless they also had a Mach warning (that the plane was going faster than its mechanical limits).”

So far, there has been no such evidence. At night and in bad weather, however, there is also the possibility the pilots had become disoriented, or did not know which instruments to believe and therefore which warnings to prioritise.

“I don't have any more indications,”

“ Bonin is heard saying on the cockpit voice recorder, his voice still calm.

Doerr said he doubted that American pilots, who typically come from military backgrounds, would have been overwhelmed. “The European airlines select people with virtually no flight time at all and train them pretty much from the ground up,” he said.

“They are 'company babies' who rise up through the organisation. Whereas if you get your experience in the navy or air force, there's an emphasis on trial by fire.”

Thoughts?

airtractor
30th May 2011, 08:07
I don't understand the comments regarding the lack of AOA diplayed as being an issue: is it too complicated to substract Flight Path Angle from Pitch?
Pitch-Path=AOA

That is lesson 2 or 3 from any PPL training...
Am I missing something?

astonmartin
30th May 2011, 08:26
Guess what: The A330 has been retrofitted with a' backup speed scale' (BUSS) in case all three ADC's fail. The BUSS provides a coarse speed reference, based on AOA.

nitpicker330
30th May 2011, 08:29
Guess what, to activate the BUSS you need to turn off all 3 ADR's P/B's

Lemain
30th May 2011, 08:32
I believe that the stall warning alarm on the A330 is derived from some temperature probes (hot-wire flow rate type?) and control surface status? i.e. Incipient stall is calculated. Does the algorithm still work when the aircraft has gone so far out of normal flight conditions? Is it even possible to test it in anything like a real-life situation?

astonmartin
30th May 2011, 08:38
@BOAC

alternate law: I thought there was a line referring to an auto-correction to prevent overspeed. I can't find it anymore. IF the PF behaved that way, it looks like a plausible scenario.

I've been in several deep stall scenario's in normal law in the sim, when preparing training scenario's in different laws. Everytime the stall would be uncontrollable, the high THS setting (max) was the cause.

There is not much THS awareness among Airbus pilots.

astonmartin
30th May 2011, 08:39
@ Lemain. Stall warning on the A330 is based on angle of attack.

astonmartin
30th May 2011, 08:41
@nitpicker Of course you could look into that screen during low workload. But what do you expect to see there, besides a normal AOA value? By the way, I agree with you that any pilot should know what are normal indications, especially attitude information.

nitpicker330
30th May 2011, 08:53
Ah what I expect to see if I bother to look is the current AOA of my Aircraft?? I don't understand your comment.?

Capn Bloggs
30th May 2011, 08:54
I take it you haven't seen the satellite photo with the flight path superimposed on It. It shows the extent of the storm system with the route going through the cells. Can you explain to us all just why the A330 went out of control after entering the system? Why did the F/O make a call to the F/As advising them of turbulence ? There are none so blind as those who will not see. Why would the plane go out of control if it hadn't been close to the coffin corner in turbulence? Why would all the ASIs stop working simultaneously and all those warnings begin (some of them false) if there was no supercooled water in the CBs to cause icing of the pitots? Please answer these questions for us.
It stalled because it ran out of speed after climbing from 35k to 38k after pilot control inputs. The report makes no mention of any buffeting and turbulence during the climb. Where in the report does it indicate the rather significant G loading, forcing the aeroplane into it's 7000fpm climb, that would be expected with flying into the top of a Cb?

Who said that you can only get the conditions that block the A330 pitot system in Cbs?

Given the benign nature of the comms with the cabin about the impending turbulence ( "in two minutes we should enter
an area where it’ll move about a bit more than at the moment, you should watch out"), I hardly think that the crew knowingly flew into a Cb.

I'm not saying they didn't fly into the top of a Cb; merely that there is no evidence to suggest they did. As for the Sat Pic, I hardly think that could be used to claim they did fly through a Cb given the scale of the image, as CONF iture has said.

Don't see something that is not there, Thermostat. :ok:

nitpicker330
30th May 2011, 09:05
I've just been trying to read through FCOM 1 Flight controls reversion section. After i took a headache pill I found that following any ADR disagree reversion to ALT LAW the protections lost are:-

1/ Load Factor
2/ Pitch Att
3/ High AoA
4/ High Speed
5/ Bank Angle
And 6/ Low Energy


So to me it appears that the aircraft would not have "pitched up" automatically during what it thought was an overspeed situation.

It was basically left to the Pilots to correct any perceived overspeed/underspeed.

jcjeant
30th May 2011, 09:12
Hi,

Interesting ... (sorry if already posted)
http://www.faa.gov/other_visit/aviation_industry/airline_operators/training/media/Appendix%203-B_briefing.pdf

nitpicker330
30th May 2011, 09:18
Further that Low speed stability protection change from AOA to Airspeed based and the symbols on the speed tape change from Alpha prot /Alpha max to Vsw.
With the flaps/slats in use and 5 to 10 kts above stall speed the Aircraft will induce a forward demand on the elevators, which the Pilot can override.

This was not applicable to AF 447 in cruise.

So any pitch up/down demand was as a result of the Pilots alone, they did not have any protections helping them.

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.

cwatters
30th May 2011, 09:26
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?

Edit: and think how far down they would have to pitch to get a sensible AoA back.

nitpicker330
30th May 2011, 09:27
Yes and a very quiet cockpit with very low air noise.

Ask21
30th May 2011, 09:34
Catastrophic situation: Not only some "system error" or circumstance - but also the potential consequence when it's not optimally handled. (Spin - stall - steep dive +70 degree - 80 - 90 degree bank angle. Upside down and stalled - you name it- )

To put the yoke forward when one get a shaker stall alarm - but the plane is not actually (fully) stalled - is not a catastrophic scenario -
A stall with 40 AoA and 10000 f/s sinkrate is catastrophic - especially if airplane looses pitch authority at that configuration.

I can not see why you should not practice even "drop wing" and steep diving to get out of stall etc - I did it. - at age 14 - -in a real sailplane - from 3000 feet. If it's not possible in the sim this year - why don't you make an appointment with an sailplane-instructor - he would be happy to guide you. OK it would not be the same as your wide body workhorse.- but perhaps for some take the mystery out of the stall and spin configurations. It could be great fun also.

nitpicker330
30th May 2011, 09:42
Yes it may work if you have enough Altitude left to pull out without over stressing the wings. Certainly in their position worth a try perhaps.

But a 200 tonne Airbus heading downhill at 10,000 fpm at less than 60 KIAS is going to be near impossible to recover before you hit the surface.

You'd have to roll 90 deg, wait for the nose to drop and the speed to quickly build then hope like he'll there was enough room left to recover without over stressing the wings.......

cwatters
30th May 2011, 09:43
I can not see why you should not be practice even "drop wing" and steep diving to get out of stall etc - I did it. - at age 14 - -in a real sailplane - from 3000 feet. If it's not possible in the sim - why don't you make an appointment with an sailplane-instructor - It could be great fun also

I agree. In a sailplane the nose usually pitches down on it's own when stalled - so you quickly get used to it pointing at the ground. If that doesn't happen in a jet I imagine some bravery is required to push the nose that far down - not least when 25% of the people in the back aren't strapped in.

Why wasn't full power applied? They can't have recognised the stall.

aeromech3
30th May 2011, 09:45
quote you: @ Lemain. Stall warning on the A330 is based on angle of attack.
Are you saying, as I have seen similar statements in this forum, that the A330 stall warning system does not compute:- Angle of attack with modifications from airspeed, flap position and pitch rate inputs?