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Cockpit voice recorder of Lion Air jet depicts pilots' frantic search for fix

reuters.com

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Re: Cockpit voice recorder of Lion Air jet depicts pilots' frantic search for fix

#121

Post by tuna-piano »

CyberFonic wrote: post #10

One of the factors that has been quickly glossed over is the low level of experience of some of the pilots in both the Indonesian and Ethopian accidents. In the USA, due to much higher levels of experience pilots have been correcting for the MCAS actions effectively and complaining about it to NASA (in order to avoid being branded as whistle-blowers by their airlines).

I don’t think there have been any reported cases where US pilots dealt with similiar MCAS issues. In fact, I’ve only seen three likely MCAS repeated nose down situations: the Lion air flight prior to the crash, the Lion crash, and the Ethiopian crash.

There was only one report I’ve seen in the NASA database related to the MAX going nose down. However, it doesn’t even appear that event was related to MCAS, as MCAS supposedly is only enabled in manual mode, and that situation happened when the plane was in autopilot. Further, the plane only dove once, not repeatedly as in Lion and Ethiopian.

Re: Cockpit voice recorder of Lion Air jet depicts pilots' frantic search for fix

#122

Post by agumonkey »

cal5k wrote: post #117
mjburgess wrote: post #65

Earlier quoted context omitted.

I think this perspective on accidents needs far more emphasis. Many accidents are unavoidable and not the result of some person failing to do some thing. The world isn't a story, people don't have much agency, and events do not happen because people want them to. These "narrative explanations" are mythological just-so stories that attribute the complex interaction of systems to individuals, organizations, etc. in nai…

This is the issue I have with the media - moreso than any particular bias, media loves to paint a narrative when, in truth, random events are more likely to blame (though in fairness this is a human flaw borne from the heuristic value of narrative). Accidents happen in complex systems - rather than burning the people involved at the stake, we should recognize the inherent complexity of safety hurtling an aluminum tub…

the more I grow, the less I understand why medias.. if twitter and facebook are dopamine abusers, traditional medias are also a kind of drug, mild intensity, but drug still

Re: Cockpit voice recorder of Lion Air jet depicts pilots' frantic search for fix

#123

Post by _archon_ »

dannyw wrote: post #17
programmer_dude wrote: post #15

What I don't understand whenever I read anything related to the MCAS system is why does it not check if the plane is in a dangerous nose dive using other sensors the plane might have? Does the average plane not have a gyroscope? My sub 500 dollar phone has both a gyroscope and an inertial measurement unit (accelerometer).

Because MCAS never assumes the input sensors could be faulty.

It's worse than this. MCAS is designed to only look at one of the two AoA sensors. If this happens to be faulty, it doesn't know, because it's not comparing the sensor to the other one. Instead of a system which can notice and account for disagreeing sensors and fail gracefully, we have a system which is a designed single point of failure and fails... lethally.

Re: Cockpit voice recorder of Lion Air jet depicts pilots' frantic search for fix

#124

Post by userbinator »

mlindner wrote: post #83
verytrivial wrote: post #62

Earlier quoted context omitted.

The Lion Air directive has instructions on page 41 of their preliminary report that include: 5. If the runaway continues after the autopilot is disengaged: STAB TRIM CUTOUT switches (both) ... CUTOUT If the runaway continues: Stabilizer trim wheel .... *Grasp and hold* This may be an overabundance of caution, or to cover other runaway events, but it reads like "you may need to physically fight the computer even when…

That's incorrect, these have haptic feedback, once you grasp it, it's not going to fight you. It looks for resistance and if it sees the resistance it doesn't continue.

Really? Here's a video of someone doing it, and it certainly looks like it tries to fight you (and the trim motor continues running) but there's a clutch that starts slipping:

https://www.youtube.com/watch?v=cQirIH_DuAs

Re: Cockpit voice recorder of Lion Air jet depicts pilots' frantic search for fix

#125

Post by 24gttghh »

oldgradstudent wrote: post #76
matt4077 wrote: post #42

Earlier quoted context omitted.

How would it even be possible for US pilots to sustainably have „much higher levels of experience“? Do non-US pilots fly only two days a week? Do they all die before age 40? This stereotype of dingy third-world airlines with incompetent, untrained pilots borders on racism. At the very least, one should notice that flying the world’s newest airliner in significant numbers is incompatible with one‘s preconceptions.

The first officer in Ethiopian Airlines Flight 302 was confirmed to have 350 flight hours, which is much lower then the US standard for the large carriers. Southwest Airlines, for example requires: > Flight Experience: 2,500 hours total or 1,500 hours Turbine total. Additionally, a minimum of 1,000 hours in Turbine aircraft as the Pilot in Command* is preferred. Southwest considers only Pilot time in fixed-wing aircr…

These are all pilot qualifications. The first officer was new and had ~200 flight hours. The pilot/captain had over 8000 flight hours. [0]

Look at Ethiopian Airlines own job postings![1]

   >Qualifications:
 Must hold a current and valid JAA/FAA or ICAO ATPL/CPL
    A current 777 type rating
    Minimum Flight time
        *3500 hours* jet time
        *2500 hours* Pilot in command on jet aircraft
        Command time in excess of 500 hours on 777
[0]https://www.ethiopianairlines.com/corporate/media/media-rela...

[1]https://www.ethiopianairlines.com/corporate/careers/vacancy

Re: Cockpit voice recorder of Lion Air jet depicts pilots' frantic search for fix

#126

Post by vgoh1 »

Wow. This is a failure from so many parties. The pilots for not knowing the correct procedure. Boeing (who should bear the majority of the blame) for allowing sensors that are not properly redundant, purchasing sensors that appear to fault on a regular basis, not properly training, and not making sure that a problem that was well understood can never happen again, the airline for not informing the next crew of problems from previous flights, the regulators of the United States and Ethiopia for allowing these mistakes to happen.

Re: Cockpit voice recorder of Lion Air jet depicts pilots' frantic search for fix

#127

Post by baq »

mlindner wrote: post #89
t0mas88 wrote: post #84

Earlier quoted context omitted.

The same applies to the trim in a 737 and any other transport class aircraft. If you move the control column in the opposite direction of trim, the electric trim and autopilot trim will cut out. The same applies to the autopilot in all types I've flown, it disconnects if you override it manually (except for CWS mode, but that's known and expected) I don't fly the 737, so I haven't read the aircraft specific books and…

Why didn't the pilots adjust the trim manually? I don't understand how any pilot would consider increasing control pressure to be normal and not automatically respond by manually adjusting the trim.

i don't want to sound condescending but it's all there in the parent comment.

Re: Cockpit voice recorder of Lion Air jet depicts pilots' frantic search for fix

#128

Post by kkarakk »

oldgradstudent wrote: post #76
matt4077 wrote: post #42

Earlier quoted context omitted.

How would it even be possible for US pilots to sustainably have „much higher levels of experience“? Do non-US pilots fly only two days a week? Do they all die before age 40? This stereotype of dingy third-world airlines with incompetent, untrained pilots borders on racism. At the very least, one should notice that flying the world’s newest airliner in significant numbers is incompatible with one‘s preconceptions.

The first officer in Ethiopian Airlines Flight 302 was confirmed to have 350 flight hours, which is much lower then the US standard for the large carriers. Southwest Airlines, for example requires: > Flight Experience: 2,500 hours total or 1,500 hours Turbine total. Additionally, a minimum of 1,000 hours in Turbine aircraft as the Pilot in Command* is preferred. Southwest considers only Pilot time in fixed-wing aircr…

can't be right, airlines literally don't hire pilots with lower than required hours. they'd be sued into oblivion and their license to operate taken away if they did that. it's an ironclad rule afaik

Re: Cockpit voice recorder of Lion Air jet depicts pilots' frantic search for fix

#130

Post by mannykannot »

l33tman wrote: post #57
cjbprime wrote: post #2

This appears to answer the question of why, given that there is a "memory item" for dealing with runaway trim that would have helped, it wasn't followed by the crew: > “They didn’t seem to know the trim was moving down,” the third source said. “They thought only about airspeed and altitude. That was the only thing they talked about.” If this is true, not only did the pilots not realize the trim was the cause of the d…

This is not true, on the released FDR data, it shows clearly that the pilot flying corrected the MCAS system's trim down adjustments at every cycle (each 10 seconds) for most of the level flight. So at least the PF must have been aware of this. It's a bit weird if they didn't talk about it though, maybe it was obvious to both pilots and they were concentrating on if they were keeping altitude and airspeed at all (the…

This got my attention too. For at least 6 minutes, the crew were coping with the problem - the aircraft was holding altitude and speed, if erratically, and they must have been getting the trim back to approximately where it should have been, or else MCAS would have driven the stabilizer to the point where it overrode the elevator authority.

In about the last minute of that recording, the pattern changes: the pilot trim inputs decreased and became much shorter, and the stick forces changed from going up and down to a sustained, high, back-force.

The article says that near the end, the captain handed over control to the 1st officer so he could look for answers. I am speculating wildly here, but could that coincide with the change in the pattern of the pilot's responses? Could it be that the 1st officer did not attempt to re-trim, or did not do it completely? Did he try to trim manually, but perhaps could not because of the load on the stabilizer? [1]. IIRC, according to Dominic Gates, it would only take two cycles of MCAS intervention until the stabilizer had reached a point where full nose-up elevator could not keep the airplane level.

The chart was published in one of Dominic Gates' Seattle Times articles, but I am not in a position to find it right now...

[1] https://news.ycombinator.com/item?id=19400157

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