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The crash of Air France flight 447 (2021)

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Re: The crash of Air France flight 447 (2021)

#111

Post by GiorgioG »

Glawen wrote: post #110
CoconutPilot wrote: post #107

One thing that stands out to me is the incorrect use of the word "law" when referring to flight modes. Is this just a bad translation? Are any native French speakers familiar with the Airbus documentation able to comment if the concepts make more sense in French?

The word loi (law) is indeed used in french controls engineering, not only for planes. See https://fr.m.wikipedia.org/wiki/Loi_de_commande_de_vol Cannot say if it is good or bad to be honest, I believe Airbus themselves decided on the English term law to translate the french term.

No it isn't. https://en.wikipedia.org/wiki/Flight_control_modes

Re: The crash of Air France flight 447 (2021)

#112

Post by kikokikokiko »

psunavy03 wrote: post #46

I fly a desk herding cats, I mean devs, for a living now. But as a Navy-trained aviator, this and the Colgan Air mishap in Buffalo always make me cringe. I can't entirely judge the crew, because the human mind is a strange thing that has ways of rationalizing truly abnormal situations and behavior. That said, an obvious Crew Resource Management failure compounded the issues here. That said, I believe aerobatics and o…

I have zero flying experience, but man, just by playing Pilotwings on the SNES and Ace Combat on the PSX, it's ingrained in me that when you stall any aircraft, be it a hang glider or a fighter jet, you put your nose down, gain speed and recover your aircraft. I am Brazilian, and since the first time I read the accident report I couldn't believe how a professional pilot could keep pitching the nose up for minutes on end on a stall situation. It made me A LOT less thrusting of the aviation industry capacity to take me safely from point A to point B.

Re: The crash of Air France flight 447 (2021)

#113

Post by goles »

sambapa wrote: post #101
goles wrote: post #65

Earlier quoted context omitted.

I don’t know if it’s any comfort to scared fliers but even in the incredibly rare circumstances you are involved in a crash? It’s gonna be over quick. It’s gonna be bang, people are gonna scream, you’re gonna be the most scared you’re ever gonna be for like 15-90 seconds and then it’s all gonna be over. That’s if you even get to hear the bang in the first place.

If you are involved in a plane crash then statistically you survive. So microscopically small chances of something bad happening times not so small chance of dying in a plane crash = nothing to worry about, you have to be incredible lucky to be so unlucky.

Maybe I’m just fucked up but I think you missed the humor in describing to a guy who is terrified of flying exactly how he would die but that it’s all gonna be okay.

Re: The crash of Air France flight 447 (2021)

#114

Post by logifail »

psunavy03 wrote: post #64
molenzwiebel wrote: post #55

Earlier quoted context omitted.

Time and time again we learn that people do stupid things under stress. Consider Transair flight 810 [1], in which a simple engine failure during takeoff results in a complete loss of the aircraft when both pilots mistakenly identify the _wrong_ engine as malfunctioning, despite identifying the failure correctly only minutes earlier. OP has an article on that crash too, actually [2]. [1]: https://en.wikipedia.org/wik…

Another very common failure mode, and really all you can do is mandate an SOP that the crew member vocalizes which engine they're turning off, and the other crew member verifies that it's the correct engine. The other answer to "people do stupid things under stress" is the common maxim that every emergency procedure in every aircraft starts the same way. Somewhere in the cockpit is probably a standard-issue mechanica…

> The other answer to "people do stupid things under stress" is the common maxim that every emergency procedure in every aircraft starts the same way

A good friend of mine [UK-based] used to fly fast jets for the RAF a long time ago (we're talking Lightning/Jaguar/Tornado).

He recently commented to me that "there were operational deployments where it went from boring to bedlam in the blink of an eye much of the time"...

Teaching humans how better to manage going from boring to bedlam is the key, I think.

Re: The crash of Air France flight 447 (2021)

#115

Post by skissane »

vkou wrote: post #104
skissane wrote: post #78

Earlier quoted context omitted.

We expect human pilots to be able to stop the plane from crashing when the airspeed is unknown. If that’s possible for humans, why not for computers?

If a computer could have done it, it would not have needed to have dropped out of normal law to begin with. When in normal law, the plane pretty much flies itself. When the computer has uncertainty with its sensors, it drops out of normal law, and expects the pilots to fix the problem. You're asking that the computer, when it is uncertain in its sensors, to the point where it can't fly under normal law, and where the…

In this case - the plane was rapidly descending, and the pilots were completely failing to do anything to fix the situation.

Maybe at some point it became clear that the pilots were doing nothing to actually save the plane, and then the computer could have been justified in ignoring them, and trying to solve the problem itself?

> If you say 'The computer', I'll have to ask you: How well did that work out for the 346 people killed by Boeing's MCAS, which, thanks to a faulty sensor, was utterly convinced that the 737 was too nose-up, and happily flew the damn thing right into the ground.

Because the programming of that computer was criminally stupid. It continued making an assumption despite the fact that the other evidence it had available to it was sufficient to conclude the assumption was false, but it wasn’t programmed to consider any of that other evidence. That a computer with crap software kills people is a problem with that crap software (and the failed regulatory system that allowed it), and not evidence against any proposal not involving such software

Re: The crash of Air France flight 447 (2021)

#116

Post by Glawen »

GiorgioG wrote: post #111
Glawen wrote: post #110

Earlier quoted context omitted.

The word loi (law) is indeed used in french controls engineering, not only for planes. See https://fr.m.wikipedia.org/wiki/Loi_de_commande_de_vol Cannot say if it is good or bad to be honest, I believe Airbus themselves decided on the English term law to translate the french term.

No it isn't. https://en.wikipedia.org/wiki/Flight_control_modes

I updated in the meantime, what isn't?

Re: The crash of Air France flight 447 (2021)

#117

Post by aaronmdjones »

throwaway110823 wrote: post #63
kloch wrote: post #52

It's tempting to blame the inexperienced first officers, their training, or the CRM failures on this flight, but the blame for this crash has to land squarely on the atrociously bad UX of the Airbus cockpit. Sensory overload and no clear readout of what is actually broken (pitot tube icing in this case) is bad but the fly-by-wire joystick configuration is what really doomed this flight. In Boeing airliners and many o…

Someone in my extended family works at Airbus as an engineer (hence the throwaway account) When I asked him about this accident, I brought up this specific point - the mechanical non-linkage. Sure, the Airbus is fly by wire (there are no "mechanics"), but you can still program one joystick to mimic the other joystick, right? As far as I know, the Airbus plane actually averages the inputs..?? [0] Anyway, he sorta-angr…

The 777 and 787 are fly-by-wire aircraft with mechanically-linked yokes. In extreme situations (one yoke is actually stuck and won't move at all), there is a breakaway on that link, and if you exert enough force upon it (like, really hulk at the thing), you can snap it. I don't know whether this has been necessary in flight, but the facility is there. The control surfaces are split between the yokes, so for example the left yoke pitch control commands the left-side elevator, making the plane still controllable with only one working yoke.

Re: The crash of Air France flight 447 (2021)

#118

Post by vkou »

skissane wrote: post #115
vkou wrote: post #104

Earlier quoted context omitted.

If a computer could have done it, it would not have needed to have dropped out of normal law to begin with. When in normal law, the plane pretty much flies itself. When the computer has uncertainty with its sensors, it drops out of normal law, and expects the pilots to fix the problem. You're asking that the computer, when it is uncertain in its sensors, to the point where it can't fly under normal law, and where the…

In this case - the plane was rapidly descending, and the pilots were completely failing to do anything to fix the situation. Maybe at some point it became clear that the pilots were doing nothing to actually save the plane, and then the computer could have been justified in ignoring them, and trying to solve the problem itself? > If you say 'The computer', I'll have to ask you: How well did that work out for the 346…

And maybe in JT 610 and ET 302, the pilots should have been justified in ignoring the Boeing computer, which was making bad decisions based on a faulty sensor reading, and was trying its damn hardest to fly the plane into the ground (And succeeded, killing everyone on board, despite the best efforts of the pilots).

How about we let the system whose sensors are functioning ultimately be in charge?

Re: The crash of Air France flight 447 (2021)

#119

Post by bombcar »

vkou wrote: post #104
skissane wrote: post #78

Earlier quoted context omitted.

We expect human pilots to be able to stop the plane from crashing when the airspeed is unknown. If that’s possible for humans, why not for computers?

If a computer could have done it, it would not have needed to have dropped out of normal law to begin with. When in normal law, the plane pretty much flies itself. When the computer has uncertainty with its sensors, it drops out of normal law, and expects the pilots to fix the problem. You're asking that the computer, when it is uncertain in its sensors, to the point where it can't fly under normal law, and where the…

> Who is ultimately in charge in a sensors-out situation? The human? Or the computer? Which of these do you believe should have the final say on flight decisions?

This is the root of the main Airbus/Boeing disagreement about design; Airbus leans towards the "pilot and dog" [37] arrangement, Boeing leans toward "let the pilot figure it out".

But the reality is the more and more the computer can handle strange situations, the further the pilots get from being able to react to even stranger situations. That doesn't necessarily mean you shouldn't have additional laws to prevent going from normal law direct to "whelp, it's your plane now, bro".

[37] Old joke: https://jalopnik.com/the-thought-of-a-single-pilot-airliner-...

Re: The crash of Air France flight 447 (2021)

#120

Post by pazimzadeh »

jcalvinowens wrote: post #91

The article misses the key takeaway from this incident IMHO. When the controls were pegged at full aft deflection, the stall warning would cease , because instrument readings in the deep stall were considered invalid by the computer. Whenever the pilot would start to push forward to recover, the computer stopped rejecting the readings, and started sounding the stall warning again! So every time the pilot started to d…

> During flight 447’s plunge toward the sea, the flight directors disappeared every time the forward airspeed dropped below 60 knots. This was because an airspeed below 60 knots while in flight is so anomalous that the computers are programmed to reject such a reading as false. Furthermore, at an angle of attack threshold which corresponded quite closely to 60 knots, the stall warning would cease for exactly the same reason. This created an unfortunate correlation, wherein Bonin would pitch up, the angle of attack and airspeed would exceed the rejection thresholds, the flight director would stop telling him to fly up, and the stall warning would cease; then if he attempted to pitch down, the angle of attack data would become valid again, the flight director would tell him to pitch up, and the stall warning would return. This perverse Pavlovian relationship could have subconsciously conditioned Bonin to believe that pitching down was causing the plane to approach the stall envelope, and that by pitching up he was actually protecting the plane against stalling.
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