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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)

#81

Post by afterburner »

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…

Averaged inputs on the sticks was the worst thing I read about back when this happened. I can't imagine a circumstance where this is desirable, and it can only lead to confusion.

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

#82

Post by mrguyorama »

oatmeal1 wrote: post #69
_cenw wrote: post #66

Earlier quoted context omitted.

Also, the PNFs hesitancy to shout "my controls" and/or hitting the priority button, especially as he moves to pitch the plane down when it was probably still recoverable. That the off-duty captain standing behind them is the first to vocalize they're at 10000 ft and stalling is indeed not great.

He did hit the priority button and say "Controls to the left." Bonin hit his priority button to take back control but didn't say he was taking back control.

The reality is there is not a single thing you can legislate or train that will prevent a pilot from flying a perfectly working plane into the ground if they get stubborn.

Aircraft emergencies are all about keeping you out of panic so that your natural instincts don't surface, because pretty much every natural or intrinsic human instinct, if followed, will just result in you flying the plane into the ground. Every sense you have is overwhelmed with "things aren't working the way I know they are supposed to and my control inputs seemingly have random results", and in a panic, your brain REALLY wants to revert to "just keep going up, away from danger", which is the opposite of what you need to do 95% of the time.

The only fix in this case would have been literally evicting that pilot from the cockpit, and there's no button for that.

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

#83

Post by bombcar »

t0mas88 wrote: post #20
bombcar wrote: post #3

Earlier quoted context omitted.

> Unlike most other airliners, the control sticks on Airbus models are not mechanically linked and the pilots cannot directly feel what the other pilot is doing. This is a very bad design - at a bare minimum an incredibly loud and annoying alarm should go off if the pilots are fighting controls, because neither knows what the plane is receiving as an input.

It has been changed after this incident. There is now an alert for dual input. The resulting Airbus system is better than traditional connected yokes, because it doesn't have the unexpected opposite input anymore (with the alert) but it does also have an override switch for the captain's side. Which means you can overpower the first officer with just a button instead of physically having to wrestle for the controls.…

Of course that introduces the problem of "what if the captain is the startled pilot" - can the first office override the captain?

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

#85

Post by bombcar »

vkou wrote: post #67
bombcar wrote: post #37

Earlier quoted context omitted.

The most likely thing to help in something like this, is for the plane to realize it's going to die, and just take over. And that has usually been the "airbus way", whereas Boeing has more had a notion of throw things to the pilots often enough so they know what they're doing.

The plane can't take over when it has no idea of what it's airspeed is. That's what caused this whole chain of problems in the first place.

The plane can realize the airspeed must be incorrect, because the altimeter is dropping, the engines are at full throttle, and the nose is pointing up, ergo something must be wrong.

Even leveling the plane off would probably have recovered from the stall, if done early enough.

And the plane knew it was stalling, it kept yelling "STALL, STALL" - the stall warnings are triggered by another sensor, not the pitot tubes.

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

#86

Post by afterburner »

eastbound wrote: post #70
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…

Armchair amateur, Pitot tube failure is such a frequent occurrence that I’m angry we display any other warning than this one. - It should have a needle to eject caps on it, so that pilots don’t forget the caps (Brisbane accident, among many), - The needle should also sense, if not remove, the ice (Air France accident), - It should wake up the pilots and reset controls to fixed values for the current altitude, since w…

Pitot tube failures are incredibly frustrating. In one case it's theorized a wasp nest blocked the inside of one, after not being covered while on the ground a long time.

https://en.wikipedia.org/wiki/Birgenair_Flight_301

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

#87

Post by _cenw »

oatmeal1 wrote: post #69
_cenw wrote: post #66

Earlier quoted context omitted.

Also, the PNFs hesitancy to shout "my controls" and/or hitting the priority button, especially as he moves to pitch the plane down when it was probably still recoverable. That the off-duty captain standing behind them is the first to vocalize they're at 10000 ft and stalling is indeed not great.

He did hit the priority button and say "Controls to the left." Bonin hit his priority button to take back control but didn't say he was taking back control.

Reading the CVR again, he did in fact ask for the controls ("So give me the controls") several times, but still seemed to be under the impression that they were in overspeed, or at least had to climb.

I think my sibling comment is probably right, Bonin would've required much more severe shouting to take his hand off the stick.

Certainly worth reading: https://bea.aero/uploads/tx_elyextendttnews/annexe.01.en.pdf

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

#88

Post by mercurialsolo »

This is a fabulously well written article in the means of a technical thriller.

"All of this happened near instantaneously, leaving the pilots completely in control of the airplane with little advance warning."

Complex systems have such a low-window for handling or preventing failure that it is impossible to deal with it at manual scale unless we have a super-good control panels and copilots.

Why we need a lot more work on observability and interpretability while operating complex systems.

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

#89

Post by fakedang »

Simplicitas wrote: post #72

This brings up an interesting question: If the control was fully automated, the computer entirely in charged, would this have happened?

As shown in the article, when the pitot readings were incorrect and the initial 3 second stall warning was displayed, a veteran pilot would simply have had to let the plane continue on in normal law mode, without any action. But Bonin was too overreliant on the incorrect action from the autopilot (moving to alternate law), which itself was an incorrect result from the incorrect readings of the Pitot tubes.

Pitot tube icing is one of those issues where automation becomes useless entirely.

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

#90

Post by mrguyorama »

t0mas88 wrote: post #25
dabluecaboose wrote: post #5

Earlier quoted context omitted.

Even as a flying novice, I was screaming to myself when they kept trying to pull up in a stall. I guess there had to have been some element of panic clouding their judgement, which is why pilots need to drill routine into their head so hard.

In normal law an Airbus doesn't stall with full back stick, that would just result in maximum AoA not a stall. In this case it had degraded to loose some of those protections due to icing of the sensors. That was confusing to the junior co-pilot, and they skipped basic procedures on who has control resulting in opposite inputs and a loss of control.

But if you are in a stall at 35k feet, there is never a situation in which the corrective action is to pull up, especially not to max AoA. You aren't anywhere near the water, you should be trying to gain speed.

Bonin just went to primal instincts, full fight or flight, and was "taking matters into his own hands" even despite the fact that he was aware he wasn't doing anything useful. The other pilot even told him to stop, but he didn't. He wasn't a copilot in this scenario, but rather a direct adversary to recovery of the plane.

He should have been treated as a rogue pilot the second he started panicking, but the other guy was kinda busy. He was not acting rationally in any way. Had he dropped dead from a heart attack, AF447 would be an interesting anecdote instead of a tragedy.

How do you train pilots for: "In very rare cases, especially during a crisis, you may need to physically harm your coworker to prevent them from causing the death of hundreds of people, but definitely don't do it if you're the one causing the problem, which you will never figure out if you ARE the one causing the problem"

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