The crash of Air France flight 447 (2021) • Hacker News Board

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

#161

Post by benhurmarcel » Fri, Aug 11, 2023, 6:47 PM UTC

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…

If a “needle” worked to remove the ice, that’s what they would use instead of a complex anti-ice system.

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

#162

Post by jimmaswell » Fri, Aug 11, 2023, 6:50 PM UTC

mrguyorama wrote: post #82

oatmeal1 wrote: post #69

Earlier quoted context omitted.

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 se…

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

Military jets have such a button. Maybe commercial needs to take some inspiration?

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

#163

Post by flerchin » Fri, Aug 11, 2023, 6:50 PM UTC

markus_zhang wrote: post #49

mcbutterbunz wrote: post #40

Earlier quoted context omitted.

> But lack of sleep is a real issue. Even more on the US side since rest rules are worse than European. Somehow it doesn't get the attention it deserves. IMO this is almost a cultural issue. We don't prioritize sleep as much as we should and even hold lack of sleep as something to be idolized (i.e. sleep = laziness). How many times do we hear about those CEOs or Founders that wake up super early after only 5 hours of…

A side topic, I'm aghasted to know that preschool and primary schools start at 7:40. God it's going to be tough for my son who refuses to sleep before 10pm.

You can enforce a bedtime for any child. You have to consistently enforce it for at least 2 weeks, and you have to consistently wake them up earlier. Depending upon the child, it may be a battle for 2 weeks, but it's a battle you can win, if you want to.

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

#164

Post by ericbarrett » Fri, Aug 11, 2023, 6:52 PM UTC

cccbbbaaa wrote: post #160

ericbarrett wrote: post #152

Earlier quoted context omitted.

It seems like an avionics warning—“conflicting control input” or the like—would go a long way here, and not change anything fundamental. Maybe Airbus implemented that since?

There is an audible “dual input”, which was triggered on this flight.

Interesting, thanks! I’ve read a few accounts of this crash and never picked up on that.

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

#165

Post by turnsout » Fri, Aug 11, 2023, 6:53 PM UTC

logifail wrote: post #123

turnsout wrote: post #56

Earlier quoted context omitted.

To be fair, it sounds like this crash caused airlines and regulators to demand much more adverse event training, including high-altitude stall recovery. But according to the article, Airbus hasn't addressed the split control issue…

> this crash caused airlines and regulators to demand much more adverse event training, including high-altitude stall recovery Q: How many pilots would attempt a stall recovery if the aircraft's instruments were not indicating they were stalled?

In the case of 447, they were warned about a stall, repeatedly.

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

#166

Post by refurb » Fri, Aug 11, 2023, 6:54 PM UTC

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…

* 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.*

They did do that on the flight in question.

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

#167

Post by t0mas88 » Fri, Aug 11, 2023, 6:54 PM UTC

mrguyorama wrote: post #90

t0mas88 wrote: post #25

Earlier quoted context omitted.

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…

I have an instructor rating, part of training is exactly that. If someone freezes up at the wrong moment, be prepared to use violence to get them off the controls.

One trick that often works is to put your hand in front of their eyes. Humans have a deep instinct to want to see at all times, so they'll let go of the controls and use their hands to remove yours. No need for physical harm.

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

#168

Post by jimmaswell » Fri, Aug 11, 2023, 6:55 PM UTC

flerchin wrote: post #156

cedws wrote: post #126

Earlier quoted context omitted.

I also wonder why airspeed is derived by some formula applied to the measurement of flow along a tube that can be blocked by ice and become useless. Why not use GPS primarily and fall back to that if needed? Or the other way around even. If you expect an instrument to routinely fail, it just seems logical to at least have a backup.

Jetstreams are hundreds of kph. Meaning groundspeed can be hundreds of kph off of airspeed. Meaning GPS is a very poor backup airspeed indicator.

It's trivial to calculate true speed from altitude and ground speed. Is the altitude not reliable?

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

#169

Post by t0mas88 » Fri, Aug 11, 2023, 6:57 PM UTC

mrguyorama wrote: post #92

dabluecaboose wrote: post #60

Earlier quoted context omitted.

Yeah, I guess as someone who's had minimal instruction it seemed obvious. But reading the article it's clear that the junior FO was trained basically exclusively on the fly-by-wire Airbuses and probably didn't have that intuitive understanding when that protection was stripped away.

The plane in this case doesn't matter. No training for stalls ever tells you to pull up. It's directly opposed to how stalls ARE trained. This pilot was a chaos monkey, and the other pilots were unable or unwilling to get the chaos monkey out of the situation. He had completely reverted to human instinct, which is terrible for flying, and also was letting himself override his copilot, who was handling the situation m…

Indeed. Other controls would have caused a wrestling match over the controls with probably the same outcome.

I believe the best solution is what Airbus implemented after this incident. An alert if there is dual input, and a button for the captain's side to override the other side. No need to wrestle, press the priority button and take over control.

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

#170

Post by logifail » Fri, Aug 11, 2023, 7:03 PM UTC

turnsout wrote: post #165

logifail wrote: post #123

Earlier quoted context omitted.

> this crash caused airlines and regulators to demand much more adverse event training, including high-altitude stall recovery Q: How many pilots would attempt a stall recovery if the aircraft's instruments were not indicating they were stalled?

In the case of 447, they were warned about a stall, repeatedly.

> In the case of 447, they were warned about a stall, repeatedly

It's not that simple.

When the aircraft's computer considered the inputs invalid, the stall warning was muted. When they decreased the pitch (would be essential to recover from the stall!) the stall warning sounded.

"The angle of attack had then reached 40°, and the aircraft had descended to 35,000 feet (10,668 m) with the engines running at almost 100% N1 (the rotational speed of the front intake fan, which delivers most of a turbofan engine's thrust). The stall warnings stopped, as all airspeed indications were now considered invalid by the aircraft's computer because of the high angle of attack. The aircraft had its nose above the horizon, but was descending steeply.

Roughly 20 seconds later, at 02:12 UTC, Bonin decreased the aircraft's pitch slightly. Airspeed indications became valid, and the stall warning sounded again; it then sounded intermittently for the remaining duration of the flight, stopping only when the pilots increased the aircraft's nose-up pitch. From there until the end of the flight, the angle of attack never dropped below 35°."[0]

[0] https://en.wikipedia.org/wiki/Air_France_Flight_447