Ethiopian Airlines Boeing 737 pilots 'could not stop nosedive'

Unfortunately, ejection seats suck to use. Like, mild chance of killing you, very high chance of breaking bones, almost certain to make you a few inches shorter from compressing your spine levels of suck. This is assuming that you don't hit anything on the way out, of course - and don't land in the fireball. And that's with trained, fit pilots who are expecting the ejection. Can you imagine what happens to Grandma who's started to lose bone density? Or the baby on their mother's lap? And that's before you start considering the issues with having that many parachutes and rockets in close proximity, or the weight.

So that's why planes don't have features to save these people.

Yes, the sensor is appropriate for use as an input to a safety critical system.

No, it is not appropriate for a safety critical system to behave in such a manner where if that one vane failed, to kill everyone on board.

While the sensor caused the cascade via it's input, it was the implementation of the listening system that allowed the rest to happen.

Safety critical systems are designed with graceful degradation in mind. The fewer sources of information the system has, the more conservative it's contribution to the overall state of the system should become.

There should have been integration with the second AoA sensor, pilot notification of disagree, and a lessening of the authority of the system in favor of the pilots.

The pilots could then have turned the plane around, and landed it.

Boeing is also on the hook for not highlighting the compounding risk presented by an airspeed unreliable failure compared with a stab trim runaway.

I'd also wager they should have had an MCAS disable separate from the stab trim cutout as a result.

Sure, but that doesn't mean going the other way and deflecting blame from Lion Air and the pilots.

>The pilots apparently did not take an action that _may_ have saved the plane (we now know it may not have).

Disabling electric trim would have absolutely saved the Lion Air flight just like it did when the same issue cropped up on the previous flight. Some speculated (which appears to be incorrect) that the Ethiopian Air flight was in a situation that they couldn't recover from, but the Lion Air flight was not in that situation.

The Lion Air pilots identified that the trim was incorrect and reset it at least 20 times. It's fair to fault them for not coming to the conclusion that the electric trim system was malfunctioning and that they should disable it.

In the case where prescribed procedures are followed, and don't work well enough (i.e. you're still stuck in a bad situation that continues to degrade), you're basically asking for experience to manufacturer an alternative on the spot. That's rather like a Hail Mary pass, in terms of logic. It's a 'well maybe maybe not'.

I'm not sure how that progresses the conversation, and yet people on HN keep bringing this up as if it's relevant without actually showing any new dots let alone connecting them. Setting aside hard evidence proving experience is a factor, you don't even have a hypothesis of how it might be a factor.

He had only 200 hours of flight time. Well so fucking what? You have to make the case. It doesn't make its own case. The reason why the U.S. has a higher regulatory requirement for experience is because of Colgan Air 3407, in part, even though the experienced pilot in command showed the same incorrect response to stall warning as the second in command, both of which were contrary to training, and also the training itself was inadequate.

I've got quite a lot more total time experience than the second in command of the Ethiopian airlines pilot. I can't tell you with any meaningful certainty I would have done anything different.

I'd say my life experience is more relevant than my flight hours experience. And my life experience when encountering either human or computer confusion at only 1000 feet above the ground, is to consider it somewhere between incompetency and sabotage. I would not be diagnosing that shit either way, I'd disconnect all of it.

And I would be irate at discovering a form of autopilot (MCAS is a safeguard, or control law) that I was not previously informed of by either my airline, or regulator, or the airplane manufacturer. And in fact, U.S. pilots are pissed at exactly that. Including or even in particular the ones with 1500+ hours.

If the pilots are reactive or even panicked at the unexpected uncommanded pitch behavior, they may have been doomed right from that moment. The previous flight, Lion Air 34, the pilots likewise did not immediately cutoff autotrim. We have no transcript from that flight either. None of these pilots have been told of, or simulator trained, an MCAS upset scenario. Startle factor is relevant and can cause total cockpit breakdown. The 737 PCU design flaw and subsequent accidents show this. Can problem specific training mitigate crashes? Sure. How would these pilots have received MCAS upset training when they don't even know MCAS exists and the simulators didn't have such an failure option? And should they now be required to have such training? Including simulator training?

As for why MCAS is triggered below 1500' AGL in the Ethiopian Airlines case, that is a very good question. I have not seen the altitude above which MCAS is supposed to apply, and I haven't discovered how that trigger altitude is determined, radar altimeter?

Most of the facts we still don't know.