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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

#261

Post by flappysquirrel »

jandrese wrote: post #249
itronitron wrote: post #247

Earlier quoted context omitted.

Seems like it would have been sufficient to cause the crash, or are you saying that if the pilots let MCAS do its thing that the plane would not have crashed?

Crash causes: 1. Faulty MCAS 2. Insufficient pilot training 3. Boeing design changes (MCAS used to be disabled automatically if the pilot applied sufficient counter-input, this feature was removed in the -MAX series, requiring the pilot to explicitly disable the system using a separate button) Take away any 1 of those causes and the plane doesn't crash. They all had to happen at the same time for these two tragedies…

>MCAS used to be disabled automatically if the pilot applied sufficient counter-input, this feature was removed in the -MAX series

What was the reasoning behind this change?

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

#262

Post by 7952 »

jve wrote: post #4

In the other news, on the previous day on the same plane there was a retired pilot flying in cockpit who correctly diagnosed problem & told how to disable malfunctioning system: https://www.bloomberg.com/news/articles/2019-03-19/how-an-ex...

I wonder if it would be useful to have a mission control style setup that could be used in an emergency. So the pilot has a problem, the plane broadcasts data, humans analyse the problem, and then give advice to the pilot. The staff would specialise in an aircraft type, and do regular simulated training.

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

#263

Post by ddalex »

rational_indian wrote: post #45
wereHamster wrote: post #41

Earlier quoted context omitted.

Note that AoA and the angle of the airframe body (relative to the horizon) may not be the same. Even if the airframe is pointing downwards (below the horizon) or really high up doesn't mean the wings have a sufficient AoA to generate lift.

Can't the IMU sense if you are generating lift (or not)?

That's a very interesting thought. How would you do it? You can only sense the acceleration - if it's lower than 1G you're falling. The angular momentum doesn't actually tell you anything in an aircraft.

I wonder if it's possible to estimate the local air speed based on ground speed (GPS) and local weather data (can we measure wind speed at altitude?).

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

#264

Post by 24gttghh »

oldgradstudent wrote: post #258
24gttghh wrote: post #255

Earlier quoted context omitted.

They only introduced that rule in 2013 as your link states, and it doesn't seem like most other places bother with such high requirements.[0] "On Ethiopian flight 302, the first officer may have had just 200 hours, but the captain, a 29-year old career Ethiopian Airlines pilot, had a very respectable 8,000 hours under his belt. There’s no indication, at this point in the investigation, that crew experience may have b…

> They only introduced that rule in 2013 as your link states The major carriers were always stricter. The 2013 rule changed to address a problem at the regional carriers. > and it doesn't seem like most other places bother with such high requirements.[0] Which I explicitly stated in my original post: >>> The European carriers, on the other hand, do not have such strict requirements. > I still don't see why you are ha…

Fair enough. Back to the actual issue here:

"When it was rolled out, MCAS took readings from only one sensor on any given flight, leaving the system vulnerable to a single point of failure. One theory in the Lion Air crash is that MCAS was receiving faulty data from one of the sensors, prompting an unrecoverable nose dive.

In the software update that Boeing says is coming soon, MCAS will be modified to take readings from both sensors. If there is a meaningful disagreement between the readings, MCAS will be disabled."

https://www.nytimes.com/2019/03/21/business/boeing-safety-fe...

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

#265

Post by livatlantis »

foldr wrote: post #253
jandrese wrote: post #246

Earlier quoted context omitted.

The copilot actually suggested to use the airbrakes at one point. Neither Bonin nor Robert, nor the third crew member (Marc Dubois, the captain) who entered the cockpit 90 seconds into the episode, recognized that the aircraft had stalled despite multiple cues. In the confusion, Bonin misinterpreted the situation as meaning that the plane was flying too fast and actually reduced the thrust and moved to apply the spee…

I know what the Popular Mechanics article says, but I cannot find any confirmation of the key points in the official accident report, which I take to be much more reliable.

Here's the official report: https://www.bea.aero/uploads/tx_elyextendttnews/annexe.01_04...

Page 28: The right-seat co-pilot Bonin says "j’ai l’impression qu’on a une vitesse de fou non qu’est-ce que vous en pensez ? "(I feel like we're speeding like crazy, what do you think?")

Page 31: Same co-pilot "mais je suis à fond à cabrer depuis tout à l’heure " (But I've pulling back completely for a while), and this while the cockpit is screaming "Dual Input" (so this means that the other pilot was inputting as well, thus "unbeknownst" in my original comment).

Same page, right after, the captain says, "non non non ne remonte plus là" (No, no, no, don't pull back any further".

If you read the entire transcript, it's clear that there was persistent confusion as to who was in control, despite the dual-input warnings. AF447 is widely considered to be a failure in CRM, and a failure to recognize that they were in an aerodynamic stall (again, despite the warnings).

They didn't trust the plane with the information it was providing, which is probably why they ignored these warnings.

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

#266

Post by foldr »

livatlantis wrote: post #265
foldr wrote: post #253

Earlier quoted context omitted.

I know what the Popular Mechanics article says, but I cannot find any confirmation of the key points in the official accident report, which I take to be much more reliable.

Here's the official report: https://www.bea.aero/uploads/tx_elyextendttnews/annexe.01_04... Page 28: The right-seat co-pilot Bonin says "j’ai l’impression qu’on a une vitesse de fou non qu’est-ce que vous en pensez ? "(I feel like we're speeding like crazy, what do you think?") Page 31: Same co-pilot "mais je suis à fond à cabrer depuis tout à l’heure " (But I've pulling back completely for a while), and this while t…

>Page 31: Same co-pilot "mais je suis à fond à cabrer depuis tout à l’heure " (But I've pulling back completely for a while), and this while the cockpit is screaming "Dual Input" (so this means that the other pilot was inputting as well, thus "unbeknownst" in my original comment).

Perhaps you didn't notice this, but immediately after the point in the transcript you refer to, there's an exchange between the pilots where they establish who's in control (see "vas-y tu as les commandes" at 2 h 13 min 46,0). There is no way to be sure, but it seems probable that this exchange was prompted by the dual input warnings.

>They didn't trust the plane with the information it was providing, which is probably why they ignored these warnings.

There is no indication that they ignored the dual input warnings.

Linking the control sticks doesn't magically resolve problems caused by a breakdown in cockpit discipline. If both pilots are going for the controls at the same time, you're going to have problems. The warning system seems to have done its job, insofar as it prompted the pilots to figure out who was in control.

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

#267

Post by livatlantis »

foldr wrote: post #266
livatlantis wrote: post #265

Earlier quoted context omitted.

Here's the official report: https://www.bea.aero/uploads/tx_elyextendttnews/annexe.01_04... Page 28: The right-seat co-pilot Bonin says "j’ai l’impression qu’on a une vitesse de fou non qu’est-ce que vous en pensez ? "(I feel like we're speeding like crazy, what do you think?") Page 31: Same co-pilot "mais je suis à fond à cabrer depuis tout à l’heure " (But I've pulling back completely for a while), and this while t…

>Page 31: Same co-pilot "mais je suis à fond à cabrer depuis tout à l’heure " (But I've pulling back completely for a while), and this while the cockpit is screaming "Dual Input" (so this means that the other pilot was inputting as well, thus "unbeknownst" in my original comment). Perhaps you didn't notice this, but immediately after the point in the transcript you refer to, there's an exchange between the pilots whe…

Oh, I don't think I alluded to linking the control sticks... perhaps you intended to respond to another comment?

As for the dual input thing, there are 6 instances of the the warning. We can't really know what the pilots were thinking, but I believe page 31, from when Bonin says, "je suis à fond à..."... and then Robert à "attends moi j’ai des j’ai des commandes moi hein" a little later, "alors donne moi les commandes à moi les commandes", and 4 warnings Dual Input between them (in the space of about a minute and a half)...

I think it's fair to say that it wasn't super clear who was in control.

I'll make no comments about which system is better since I have no direct experience of flying in such environments (have only piloted small aircraft with mirrored controls, but with clear "Commande à droite/gauche" to establish PF, with my instructor). But à priori, I would imagine both systems work fine if used well.

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

#268

Post by anigbrowl »

cal5k wrote: post #229
anigbrowl wrote: post #224

Earlier quoted context omitted.

Oh, let's be calm and sober about this, and passively accept the existence of accidents rather than re-examine organizational, business, or economic premises. So much easier to blame the media. Craven excuse-making and responsibility avoidance at its worst.

...except for the part where I say we should examine the root cause and make appropriate adjustments? Or should we find every software developer who ever worked on the 737 MAX and throw them in jail? Because brutal punishment of errors is what leads to a culture of quality improvement, right?

No. You chose to start out pointing the finger of blame at the media and adding a vague statement about fixing the issue is mere lip service.

You now go to the opposite extreme, employing the fallacy of the excluded middle and emotive language like 'brutal punishment' to invalidate an argument that was never made.

Your dishonesty only highlights the weakness of your position.

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

#269

Post by jeremysmyth »

kayfox wrote: post #216
acqq wrote: post #11

Earlier quoted context omitted.

Exactly. It was not "runaway" in the sense of "continuously doing the same." Something was happening, from the point of view of the pilot and co-pilot "at random." (Not to mention that on the previous models exactly such pattern was effectively impossible to happen). The faulty non-redundant sensor was producing false reading and that was the input to the to the pilots completely unknown MCAS which then moved the nos…

"Runaway" in the sense of "its moving in a undesired and unexpected direction and continues to do so despite attempts to stop it".

"Runaway" is a term of art here. Redefining it for this conversation is unhelpful.

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

#270

Post by foldr »

livatlantis wrote: post #267
foldr wrote: post #266

Earlier quoted context omitted.

>Page 31: Same co-pilot "mais je suis à fond à cabrer depuis tout à l’heure " (But I've pulling back completely for a while), and this while the cockpit is screaming "Dual Input" (so this means that the other pilot was inputting as well, thus "unbeknownst" in my original comment). Perhaps you didn't notice this, but immediately after the point in the transcript you refer to, there's an exchange between the pilots whe…

Oh, I don't think I alluded to linking the control sticks... perhaps you intended to respond to another comment? As for the dual input thing, there are 6 instances of the the warning. We can't really know what the pilots were thinking, but I believe page 31, from when Bonin says, "je suis à fond à..."... and then Robert à "attends moi j’ai des j’ai des commandes moi hein" a little later, "alors donne moi les commande…

You referenced an article that blamed the crash on the fact that the control sticks weren't linked.
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