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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

#131

Post by Darthy »

isolli wrote: post #75
SmellyGeekBoy wrote: post #58

Earlier quoted context omitted.

This is why I refuse to listen to these things when they're released. The thought of eavesdropping in on someone's frantic hopeless fight for survival just doesn't sit right with me.

Agreed. It reminds me of the final scene of Grizzly Man, when Herzog listens to the audio recording of the bear enthusiast and his girlfriend being mauled to death. Herzog puts the headphones down, visibly shaken, and comments (paraphrasing): nobody should have to listen to that.

He actually says to the mother: Jewel, you must never listen to this.

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

#132

Post by pkd »

mlindner wrote: post #85
gojomo wrote: post #7

Earlier quoted context omitted.

That's the most amazing revelation to me so far. The same plane had an identical uncontrolled-dive problem the day before, which required an emergency power cut to the improperly-engaged motor, and somehow that incident didn't ground the plane or even result in any effective advisory to the next crew. Further, the Bloomberg story reports: "The Indonesia safety committee report said the plane had had multiple failures…

Just to be clear this is not "an uncontrolled dive problem". The amount of misreporting on this incident is maddening. When trim is adjusted you can feel it in the controls as the control stalk will put increasing pressure against you because of the trimmed controls. If you get increasing pressure on your controls the correct response is to adjust the trim to stop it. This is not a problem for any competent pilot.

Your comment reads like you're blaming it on the incompetence of pilots, although I don't think that's what you mean. Can you clarify your comment a bit more?

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

#133

Post by moftz »

vultour wrote: post #102
chrisseaton wrote: post #74

Earlier quoted context omitted.

I don't understand do you think they're listening to music or something? Having a headset on doesn't stop you hearing noises in a cockpit. How did you think all the other verbal alarms and callouts worked if they can't hear anything?

Those all go into the headset as well AFAIK. Many pilots use noise cancelling headphones.

Noise cancelling headphones would still let you something clicking right in front of you. In fact, open-back noise cancelling headphones would be better to wear than something that just muffles the noise if you need to hear your environment but just want to cut out the hum of the engines.

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

#134

Post by refurb »

_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…

This is a valuable comment. Most people ask “why have MCAS at all?”.

Well, AF477 shows that sometimes you need it.

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

#135

Post by VBprogrammer »

mannykannot wrote: post #130
l33tman wrote: post #57

Earlier quoted context omitted.

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 tr…

Anyone who's ever piloted an aircraft would try to re-trim against pitch forces. It's inconceivable that the pilot for some reason just failed to do that. I'm not sure exactly what force it takes to get full nose up elevator at flying speed but it will be in the range of dozens of kilograms.

I personally wonder if there is potentially a thermal cut-off on the trim motor which could have been activated by this trimming and re-triming. Or even an outright failure of some part of the system.

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

#136

Post by coredog64 »

dvdkhlng wrote: post #77
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…

I'm just wondering: it looks like the absolute trim angle is not visible anywhere in the cockpit? The trim wheel takes multiple revolutions to adjust trim between min/max limits, so looking at the wheel itself, you can only every see changes, not values. Unless you notice the change while it happens, you won't have any indication as to the unusual trim angle? Thinking about that I wonder whether there was even a meas…

Earlier versions of the 737 (up to next gen) have noisy trim wheels that are difficult to ignore.

AIUI, runaway trim has always been a possibility and the trim wheel design helps to surface that it’s happening.

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

#137

Post by alistairSH »

chrisseaton wrote: post #107
vultour wrote: post #102

Earlier quoted context omitted.

Those all go into the headset as well AFAIK. Many pilots use noise cancelling headphones.

If the deliberate clack of the trim wheel also goes into the headphones then why are we having a discussion about whether headphones stopped them hearing the deliberate clack of the trimwheel?

My guess is the electronic beeps and boops could be piped into the headsets, but the mechanical clack-clack of the trim wheel is not.

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

#138

Post by mikejb »

mlindner wrote: post #90
mikejb wrote: post #5

I'm trying to imagine the horror the pilots (and passengers) were feeling. Imagine your car slowly starting to shift sideways into incoming traffic, and no matter how hard you pull the steering wheel, you can't get it back. Horrifying.

Except that's not what occurred. They had control of the aircraft. The controls were never inoperative.

> They had control of the aircraft. The controls were never inoperative.

I think you're missing the point. In hindsight it's easy to say "this is what you could/should have done", and some are knowledgeable or lucky enough to either find the solution themselves, or have someone tell them before it's too late.

In two instances this wasn't the case. The pilots weren't able to regain control of the aircraft. And that lack of control, with the full knowledge of impending doom, must be a terrifying feeling.

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

#139

Post by mikejb »

isolli wrote: post #75
SmellyGeekBoy wrote: post #58

Earlier quoted context omitted.

This is why I refuse to listen to these things when they're released. The thought of eavesdropping in on someone's frantic hopeless fight for survival just doesn't sit right with me.

Agreed. It reminds me of the final scene of Grizzly Man, when Herzog listens to the audio recording of the bear enthusiast and his girlfriend being mauled to death. Herzog puts the headphones down, visibly shaken, and comments (paraphrasing): nobody should have to listen to that.

This is the scene you're referencing [1]. You can actually see his hand shaking while listening to this. His reaction alone is enough for me not to want to hear it.

[1] https://youtu.be/5SJiOZdAWco?t=174

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

#140

Post by jacobush »

WalterBright wrote: post #49
TheSpiceIsLife wrote: post #40

Earlier quoted context omitted.

And sounds ? The trim wheels moving also makes a sound?

Yes. The ratcheting sound is deliberate, so the pilots don't need to see the wheels spin to know the trim is running. Also note that there's a white stripe on the wheel so it's easy to see it is running.

Someone else in the thread said newer models don't make a sound.
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