Desitter :- 228 people went to the bottom because a pilot hearing a stall warning pulled the stick back. Given the pilot's actions. a Sopwith Camel in this event would have have had the same outcome, except the Sopwith wouldn't have been screaming "stall" in his ear.
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Everybody talks now about the pilot`s performance , but it`s not economic interesting to talk about the 2 F/Os.
If instead of 2 F/Os they had 2 Capts and 1 F/o how it was years ago, probably they had more chances. Aviation is a big more or less. |
Given the pilot's actions. a Sopwith Camel in this event would have have had the same outcome, except the Sopwith wouldn't have been screaming "stall" in his ear. This accident looks more and more like a flying skills issue, rather than design or software issue. And by implication an Air France training problem. It falls under the heading.. "Flight with unreliable airspeed." In general terms if you suspect that you have "unreliable airspeed" as a pilot, you stick to "datums." Put the power at a sensible figure, and set the attitude at a sensible attitude for that phase of flight. That will keep you safe. Having settled that down, diagnose the problem. Plane, Path, People. .... or similar. What you do not do is plant the sidestick in the back stop and expect a good outcome. |
Thoughts on the initial climb and later, the implications of deep stall.
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Originally Posted by gums
(Post 6480095)
Good math, Cog. Maybe go further and calculate the AoA required for those parameters. Then re-read my re-post about the Viper deep stall AoA and descent rate and indicated airspeed. |
Sound asleep? Smooth ride?
If the pilot resting had to be called to the flight deck by the PNF, does this infer that the plane wasn't doing anything abnormal, at that point, that would have alerted the sleeping pilot?
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Many have asked why the PF continued to pull back as the plane descended since it clearly indicated a stall. Maybe the FO disregarded the Altitude/VS data as well. Consider this:
He almost certainly would have disregarded any airspeed indications, so he's already thinking there's a pitot problem. Next thing he knows, the VSI varies between +7000 and -10,000. He's never seen those values before. Could he have assumed that the entire pitot-static system had gone bad? The poor fellow now resorts to his last instrument- the attitude indicator. When he pulls back, the stall warning goes off, release the back pressure, and it returns. Catch 22 in his mind. Even if he knew that the stall warning would disappear below 60kt, if he had any idea that his airspeed was indeed below 60, he would probably have reacted more appropriately. They probably put it all together when the RA started functioning and gave a "TOO LOW TERRAIN" alert, but at 10,000fpm, 15 seconds wasn't nearly enough time. It must truly have been horrific in the cockpit. Flying in IMC, and none of your instruments or control inputs making any sense. RIP. |
Bearfoils earlier post
What would explain the need for constant roll left, to maintain SL? damage? AIR ? cg? Likewise NU? cg? ICE? All we see is the response, not the stimulus. Whilst I can visualize the stall I cannot understand the aileron inputs. The possible causes are updraft/turbulence - very unlikely at altitude in my experience. Dutch roll - wrong duration of control input. Asymmetric ice accretion ??? doubt it but.. flight control fault - side stick - computer or hydraulics or roll damper. If the published data is correct and the aircraft wasn't in a stalled condition then 30 secs of full sidestick in a non protected aircaft should see it upside down. My money is there is something missing which confused the pilots even more..... Forgive my ignorance if alternate law will stop this happening - I didn't fly the bus although I had the chance. |
Abnormal Attitude Law
Hi Check Airman,
I tend to agree. In just 46 seconds (between 2h 10 min 05 and 2 h 10 min 51) the aircraft climbed with ROC up to 7,000 ft/min from 35,000ft to “37,500 ft and the recorded angle of attack was around 4 degrees.” (which is a sensible angle of attack). They must have ridden in the updraught of a CB to climb that rapidly and still have flying speed. Subsequently, they encounter the downdraught, their instruments don't make sense, stall warnings come and go, and I think they have mistakenly gone for Wind Shear QRH attitude 17 degs with TOGA power. Edit. Once they were in Abnormal Attitude Law, the Stab Trim remained where it was last. (In this case full nose up) "The system applies an abnormal-attitude law in pitch and roll if the aircraft exceeds any of these limits in flight....... Angle of attack > 30° or < - 10° (- 15° for A319 and A321 (??? for A330)) Speed > 440 knots or < 60 knots The law in pitch is the alternate law with no protection except load-factor protection and without auto trim. In roll it is a full-authority direct law with a yaw mechanical. When the aircraft has recovered from its abnormal attitude, the flight control laws in effect are : in pitch : alternate law without protection with autotrim. in roll : full authority direct law with yaw alternate law." |
Originally Posted by bratschewurst
(Post 6479398)
What's not clear from the report is why the PF made any stick inputs at all. My understanding is that, even in alternate law, the computers maintain the pitch and roll attitudes previously commanded until the stick is moved, so presumably the aircraft would have continued straight and level, assuming that was the case when the a/p disengaged.
[...] But it does appear, if my understanding of the Airbus FBW system (gleaned mostly from these threads) is correct, that the aircraft would have continued in straight and level (and unstalled) flight absent the left nose-up input by the PF. |
This new generation of low time pilots might not cost much pay wise but what do you think Air France paid for this crash? |
CVR crucial
When can we expect to see a transcript of the CVR - I would have thought that this is now crucial to a proper understanding of what the pilots thought they were dealing with.
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Razoray
No AF will not go the same way as Swissair. Everyone in SR was worried about flying with crossair but management was using cheaper pilots to undermine SR pay scales. Unlike the French the swiss had no qualms about buying foreign expertise. Air France will not fail as the government will always protect it financially and AF have a protected market as the average french citizen believes if it's not french then it's not worth eating, using or visiting. |
Some rude articles come up in not so marginal media outlets..
Wait for notorious pre occupied Fox news to have a go on the french.. 'Baby' pilot at controls of doomed Air France Airbus | The Australian |
I'm afraid when I read all these comments about speed
Stall has nothing to do with speed : it has to do with angle of attack.
It's incredible to read at all those posts wondering about the speed. A real pilot earing a stall alarm should not even care about the speed. Stall alarm = nose down instead you are dead. |
Airspeed and software
Hello,
I read yesterday a part of this thread about what to do when the airspeed is not available.
Originally Posted by David Horn
No, in this situation pitch attitude and power is the primary reference.
http://www.pprune.org/tech-log/45283...ml#post6478805
Originally Posted by Graybeard
The aerodynamics of the plane is a perfectly good airspeed indicator.
For a given weight and cg, the pitch angle (nose up/down), as shown on the Attitude Indicator, will indicate airspeed. Pitch down, and the plane speeds up; pitch up and the plane slows down. It's there staring at the pilot throughout every flight. Oh, that happens to be the basic of the Unreliable Airspeed Indicator training. http://www.pprune.org/tech-log/45283...ml#post6478838 In other words, shouldn't the autopilot software be improved to take into account this calculation and enable the autopilot to go on instead of tripping off (1)? In other words, imagine we are not talking about an airliner but about a costly military drone. Wouldn't you want the drone to come back safely when this kind of problem occurs and to develop the necessary software ? (1) " the computers controlling the flight switched off the autopilot after becoming confused by conflicting speed readings, caused by the icing up of pitot tubes monitoring the plane's velocity" : Air France crash inquiry details pilots' battle for survival | World news | The Guardian ; "From 2 h 10 min 05, the autopilot then auto-thrust disengaged" :http://www.bea.aero/fr/enquetes/vol....mai2011.en.pdf; |
Regarding the initial stall warning:
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 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. At that altitude the buffet margin at M0.82 for G - onset should be around 1,5 - 1,6g, maybe even lower given the fact that additional Roll input was commanded.. Also speed might already have been reduced to M0.8 at that point further reducing the margin. Edit: Stall warning activates even before that, thanks @HN39 for the comment. /Edit A firm Nose-Up input should be able to achieve this. Please note: Protections were already lost at that point and the Stall warning appears to have been subsequent to the Nose-Up stick command. Please also note the subsequent Roll inputs by the PF. either they were in significant turbulence or it was a sign that the aircraft was already in the incipient stage of the stall. These big Irons with full wing tanks and immense roll inertia normally don't have much tendency to 'wobble'. |
Originally Posted by rudderrat
I tend to agree. In just 46 seconds (between 2h 10 min 05 and 2 h 10 min 51) the aircraft climbed with ROC up to 7,000 ft/min from 35,000ft to “37,500 ft and the recorded angle of attack was around 4 degrees.” (which is a sensible angle of attack).
They must have ridden in the updraught of a CB to climb that rapidly and still have flying speed. P.S.: OTOH, at FL375 and M.68, AoA=4° corresponds to LF=0.78, i.e. a reducing V/S. At 215 kCAS and 700 fpm the flight path angle is about 1° up, i.e. deck angle is 5° up. |
Not the first one to question pilot response but how would you handle a stall warning with the HST at 13dg nose up ??
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Originally Posted by jcjeant
Hi,
Unreliable speed: Airbus presentation dated 26-28 September 2006. Unreliable Speed – Latest Improvements. Presented by Sourya Kahoul and Marie-Helene Combes. http://www.iag-inc.com/premium/Airbu...ableSpeeds.pdf http://www.pprune.org/tech-log/45283...ml#post6480120 |
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