Hacker News Reader

> 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.

You can see it used here: https://youtube.com/shorts/nBmPXrBpp3Y

You hear the normal 50.. 30.. etc. callouts and then when the captain goes full thrust you hear "priority left" which is the override button being pressed to pitch for go-around.

That's much nicer than what we have teaching with traditional controls. Because at that point overpowering a startled pilot is a bit hard.

The Dual Input alarm wasn't added, in fact it sounded several times during the Air France flight.

FDR visualization: https://www.youtube.com/watch?v=0a06A78iXnQ

Ah thanks. I thought I remembered from ground school that this was added afterwards.

Interesting that the FO flying from the left seat did not recognise that callout as a big thing to react to.

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

Yes, but whoever hits the button last gets control, so you can take priority back.

(Unless you manage to hit the priority button for 40 seconds - but I assume that's for locking out a broken stick that's doing inputs at rest)

Yes it will announce "priority right", but it's not normal to take control from the captain (and also highly unusual to take control from the first officer outside of training). Unless you're avoiding an immediate safety threat you would normally call out the problem but not take control.

It's a bit different for a training captain like in the video. They know these are the first officer's first landings on the real aircraft, so when things go wrong they take over.

https://safetyfirst.airbus.com/app/themes/mh_newsdesk/docume...

Section 6

> When a dual input situation is detected, the two green priority lights located on the cockpit front panel flash simultaneously.

> After the visual indication has been triggered, a synthetic voice “DUAL INPUT” comes up every 5 sec, as long as the dual input condition persists.

According to Wikipedia, this warning system worked as intended:

> Confused, Bonin exclaimed, "I don't have control of the airplane any more now", and two seconds later, "I don't have control of the airplane at all!"[42] Robert responded to this by saying, "controls to the left", and took over control of the aircraft.[83][44]

> He pushed his side-stick forward to lower the nose and recover from the stall; however, Bonin was still pulling his side-stick back. The inputs cancelled each other out and triggered an audible "dual input" warning.

> ...

> Bonin heard this and replied, "But I've been at maximum nose-up for a while!" When Captain Dubois heard this, he realized Bonin was causing the stall, and shouted, "No no no, don't climb! No No No!"[85][44]

> When Robert heard this, he told Bonin to give him control of the airplane.[2] In response to this, Bonin temporarily gave the controls to Robert.[44][85][2] Robert pushed his side-stick forward to try to regain lift for the airplane to exit the stall. However, the aircraft was too low to recover from the stall. Shortly thereafter, the ground proximity warning system sounded an alarm, warning the crew about the aircraft's imminent crash with the ocean.

> how many of these accidents can come down to the pilots forgetting the most basic things.

This is factually incorrect.

If you read the Final Report you will see that the FP1 (the one that have placed the abnormal inputs in the side stick) did not had the appropriate training; actually the scenario that happen has not even in the trainings (Nightly mid-atlantic flight with screen disagreement with one of the FP missing that I’m normal law).

At least for me, this accident was one of the top 3 most important in terms of safety measures and changes in aviation because the entire industry needed to think about the role of automation, training design, cockpit design, etc.

Thats makes me think of the guy who disappeared flying a Cessna test flight to Tasmania, his last report he was talking of a large object descending on him. They rekon he had lost his sense of which way up he was and it is common to fly upside down. He was likely describing the ocean. I recall reading bigger planes can also fly upside down for long distances without piloting, maybe something like that was going on. If you think you are the wrong way up and try to get down, you are going to go up.

here is the story - https://en.wikipedia.org/wiki/Disappearance_of_Frederick_Val...

Are you thinking of Helios Airways Flight 522? That Ethiopian Airlines flight was a hijacking.

https://en.wikipedia.org/wiki/Helios_Airways_Flight_522

The same author as the OP also has a great article on Helios 522: https://admiralcloudberg.medium.com/lost-souls-of-grammatiko...

Sorry, yes I am. Thank you. I guess I saw a few flight disaster things recently and got them mixed up.

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.

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 much better.

People act like this situation wouldn't have happened had they had boeing style connected controls, but it's pretty likely that in this state, Bonin would have actively been wrestling with the controls to point the nose up in that state too. The only way to keep Bonin from killing everyone would have been to restrain him. There is no reliable way to "knock" someone out of that kind of panic state.

Perhaps the physical effort of struggling against his co-pilot would have made him realize he was doing something wrong. It's too easy to pull back full on a fully non-mechanical control, and just lock up there.

No, this situation is the same as when lifeguards are warned about saving panicking and drowning people, in that if you don't handle them in specific ways they will happily drown you in their panic. You cannot rely on "shaking someone out of it" in these circumstances because there is no reliable way to force the brain to reject it's panic instincts and return to rational thought.

The only solution would have been physical restraint. Bonin was an active threat

Locking him out of the controls would have been enough (if the technology allowed it). Even just relieving him of his duty would have been enough. If Captain Dubois had been there early enough and decided to relieve him, Bonin would have almost certainly obeyed.

If he doesn't, then I guess then you can resort to force.

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.

Those existed before this accident. Bonin pressed the priority button to steal control from the other pilot, who was fixing things, at least once, and "dual input" alarms sounded pretty much the entire time the plane was falling out of the sky.

The ONLY way to have prevented Bonin from crashing the plane would have been to remove him from the controls. He was doing the same thing that lifeguards are warned about; when the human brain is in that kind of panic state, it will happily do things that it should know will inevitably lead to it's own death, like scrambling in such a way that you drown the lifeguard trying to rescue you.

With linked controls the captain would have instantly been able to tell what inputs the copilot was making and could have taken appropriate actions.

Aircraft UX should be made in such a way that there's never the slightest of doubts about something as fundamental to its function as where the inputs that its using are coming from.

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"

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.

Bonin was showing himself to be extremely resilient to coming back to reality and rationality. He needed to be physically restrained. He was far too stuck in his head to rely on anything less.

Alternatively, we just kinda have an understanding that if your pilot goes into panic, and the copilot can't figure out a way to get them out of it, everyone dies.

Of course, then what if they panicking pilot decides they have to restrain you so they can continue what they are doing?

> But why keep climbing when something is wrong?

Two possible reasons in this case.

1) Bonin might not have understood he was in full manual control, and that the computer was no longer restricting his pitch up command to the maximum advisable pitch.

2) The stall warning was intermittent on the way down, because it turns off below a certain air speed. Of course, low air speed contributes to stalling. They were stalling the whole time, but ironically as they started to gain air speed (a good thing) the stall warning would kick in because it was no longer below the lower limit for a stall warning.

Also there's the ever present reason of panic, brain-lock, confusion, etc.

Often I don’t think it is as much “forgetting” but more getting behind the events to the extent they don’t properly assess / understand the situation and then make poor choices and it is too late.

Yeah the "insane pilot error" crashes always get me.

American 587 is another example where, in response to normal wake turbulence, the pilot mashed the rudder back and forth so hard it broke the stabilizer.

There was a widespread misinterpretation/incorrect belief of the certification rules at the time of that crash.

There is an airspeed, called maneuvering speed (Va), at or below which it should not be possible to use the flight controls to remove parts of the aircraft. (The aircraft should run out of control authority or stall prior to exceeding any load limits [which is well before the removal of parts].) Every student pilot is taught this prior to passing their first knowledge test and checkride.

The problem with that is the certification rules for Va are for a single input, not for a cyclically reversing sequence of inputs (which is what the first officer of AA 587 did).

As the details became clear, this was a big topic of learning for many pilots, including myself. AA 587 was caused by the flight crew, but I don't put it into the "insane pilot error" category.

The pilot in that case was essentially taught that doing so was an acceptable thing.

The alarm in question was the same one used for invalid takeoff configuration, as hypoxia was already setting in.