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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

#201

Post by livatlantis »

_archon_ wrote: post #120
LoSboccacc wrote: post #99

Earlier quoted context omitted.

> why it would continue to drive the nose of the plane down even when the pilot is reefing on the stick to pull up well this other crash was caused by a pilot puling up a plane all the way to its ceiling and stalling it, so there's that, so things can go wrong whether if you do and if you don't allow for easy control overrides. https://en.wikipedia.org/wiki/Air_France_Flight_447#Third_in... the trick seems to find th…

The AF 447 crash is one of the reasons MCAS was created. It's the exact scenario MCAS was designed to prevent: High altitude, high-speed, nose-up stall. This was more likely than the NG and dinosaur generations of 737 due to the engine relocation forward and up (causing a pitch-up moment due to thrust). AF 447 should never have happened. The copilot crashed the plane, and the pilot and pilot on break had no indicatio…

There was both an audio and a visual indication of DUAL INPUT (light on the panel + "dual input" announced verbally). The co-pilot commanded priority take-over (from the pilot, who had just second previously done the same) without announcing it. This would have been clear if they looked at the panel that shows which side has priority, but in that confusion, their attention would've been elsewhere (airspeed and bank angle mostly).

Source (in French): https://www.vanityfair.fr/actualites/articles/vol-af-447-rio...

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

#203

Post by RcouF1uZ4gsC »

azeotropic wrote: post #95
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 U.S. is more wealthy and has a large private aviation community because private individuals can afford to buy and are permitted to fly their own small planes. As s result, it is easier for Americans to build up experience as aviators before going to work for an airline.

The other thing the US has is the 2 largest airforces in the world (The US Air Force, and the US Navy). This provides the opportunity for pilots to get a lot of flight time in jets without having to pay for it via flights schools or private aviation.

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

#204

Post by cjbprime »

verytrivial wrote: post #62
RidingPegasus wrote: post #3

Earlier quoted context omitted.

Was the trim wheel not visibly spinning out of their control? Simply because the symptoms are different should mean that stopping it via taking manual control is a recurring option.

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…

I think it's definitely to cover other runaway events, e.g. mechanical failure. (And I don't think there's haptic feedback.)

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

#205

Post by livatlantis »

jandrese wrote: post #174
benhurmarcel wrote: post #159

Earlier quoted context omitted.

> Airbus negligently averages these inputs. On an Airbus, in case of dual input the pilots get a voice alarm and a warning lights up right in front of them. Also the stick has a switch to take priority, in case the other pilot continues to give dual input.

Did AF447 not have this warning? One of the contributing factors to the crash was the copilot continuing to pull back on the stick even as the pilot attempted to push the nose down to get out of the stall.

I answered further up but: yes, it did. The DUAL INPUT alarms were audible in the cockpit voice recording. However, unbeknowst to the captain, the co-pilot used priority takeover on his side. (This was always visible on the panel + there was an audible "Priority right" warning around the end)

Source: https://www.vanityfair.fr/actualites/articles/vol-af-447-rio...

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

#206

Post by VBprogrammer »

_s wrote: post #188
js2 wrote: post #183

Earlier quoted context omitted.

Thank you for a pilot's perspective. Here's my bit of confusion though. Once you realized the stab trim was the issue, you were able to reset it and get back to normal flight. Had the problem recurred that flight, you'd probably have recognized it immediately. In the Lion flight, the pilots realize the stab trim is off because they correct it. Once they realize that, regardless of what keeps setting the stab trim to…

I think context is what helps - - I’ve just taken off, and am going through the after take off checklist: Set the airspeed, power, climb rate, heading, talking to ATC, planning the next stage of the flight - Perhaps I’ve just raised the flaps and the plane starts behaving erratically - My first / immediate thought is that my previous action led to an undesired aircraft state. - I work from that point on - I touch the…

> - My first / immediate thought is that my previous action led to an undesired aircraft state.

FYI This is shown in the Lion air preliminary report.

They select flaps 0 (from flaps 5) and a few seconds later reselect flaps 5. Unfortunately a while after that they decide to go to flaps 0 again. With any flaps selected the MCAS system is disabled.

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

#207

Post by achandlerwhite »

growlist wrote: post #72
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).

So in other words according to your theory, Boeing has made a plane that is only safe in the hands of the best pilots? Better start cancelling thousands of orders then since by definition, at least 50% of pilots will be below average.

Should be fine for any pilot qualified by US standards. Not sure about other countries.

I have anecdotally heard that some other countries train pilots as "button pushers" without really understanding what the plane is doing or having a solid understanding of flight principles.

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

#208

Post by jcims »

zaroth wrote: post #150

The previous flight had exactly the same issue. This is what that pilot wrote in the logs; After parking, the PIC informed the engineer about the aircraft problem and entered IAS (Indicated Air Speed) and ALT (altitude) Disagree and FEEL DIFF PRESS (Feel Differential Pressure) light problem on the Aircraft Flight Maintenance Log (AFML). The PIC also reported the flight condition through the electronic reporting syste…

Are the logs you're referencing a public resource? Would be interesting to look at.

>This implies it took almost three minutes for the previous crew to figure out the STAB TRIM needed to be CUT OUT after finding the trim is so wrong that they can’t hold the stick back.

I've seen a number of references to difficulty that pilots encounter managing forces of the flight controls in airliners. It seems strange to me that modern aircraft of that size would be designed in a way that aerodynamic forces on control surfaces would be allowed to translate back to control inputs in a manner that could overpower a pilot. I would think there would be some kind of scaled assist mechanism (ala power steering) in scenarios where there is a mechanical/hydraulic link. I'm guessing fly by wire scenarios wouldn't have this problem?

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

#209

Post by arianvanp »

zaroth wrote: post #150

The previous flight had exactly the same issue. This is what that pilot wrote in the logs; After parking, the PIC informed the engineer about the aircraft problem and entered IAS (Indicated Air Speed) and ALT (altitude) Disagree and FEEL DIFF PRESS (Feel Differential Pressure) light problem on the Aircraft Flight Maintenance Log (AFML). The PIC also reported the flight condition through the electronic reporting syste…

You are confusing things here. This article is about the crash that happened 6 months ago. You are comparing one and the same crash here.

The recent crash is by Ethiopian Arilines. NOT Lion Air.

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

#210

Post by sgc »

Someone1234 wrote: post #171
ams6110 wrote: post #169

Earlier quoted context omitted.

One wonders, when the prior flight landed with the stab trim system switched off, who switched it back on before the next departure? And was there no question raised as to why it was off? It's not normal to have that system switched off at any time. There are even guards over the switches to ensure they are only operated deliberately.

Maintenance attempted a repair between those two flights. They flushed the AoA system after replacing it previously.

They should have given the incoming pilots a thorough briefing of: this is what went wrong, this is how the previous pilots worked around it, this is what we did to remedy.
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