Author Topic: Lion Air crash: Jakarta Boeing 737 'had prior instrument error'  (Read 86106 times)

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Offline Kjelt

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Re: Lion Air crash: Jakarta Boeing 737 'had prior instrument error'
« Reply #450 on: March 19, 2019, 07:38:11 pm »
But the thing is that flight manuals do not provide internalized models of how an airplane really flies. You have to get that from operating the machine. And furthermore, if you operate it carefully, within normal parameters associated with passenger flight, you won't get exposed to the extreme flight regimes where this knowledge is actually useful and important. So you can have 10,000 hours in a plane and still not know what it will do in an unusual situation. This *is* something you can learn in a simulator, if it is sufficiently faithful, and I think that is one learning that I think experts can already agree on regarding the MAX: the pilots should have gotten more sim time, including time that exposes them to the behavior of the aircraft in unusual scenarios that are specific to that model.
That is the whole point is it not? According to that eetimes article Boeing claimed that any experienced 737 pilot did not need additional training or simtime for the max.
That is also why it was a big seller, the airlines did not have to invest in hours of training and that was a massive saving. It is also probably in the future the reason that if there has to be substantial additional training, the airlines will cancel their orders.
 
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Offline KL27x

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Re: Lion Air crash: Jakarta Boeing 737 'had prior instrument error'
« Reply #451 on: March 19, 2019, 07:52:32 pm »
Quote
But the thing is that flight manuals do not provide internalized models of how an airplane really flies. You have to get that from operating the machine. And furthermore, if you operate it carefully, within normal parameters associated with passenger flight, you won't get exposed to the extreme flight regimes where this knowledge is actually useful and important. So you can have 10,000 hours in a plane and still not know what it will do in an unusual situation. This *is* something you can learn in a simulator, if it is sufficiently faithful, and I think that is one learning that I think experts can already agree on regarding the MAX: the pilots should have gotten more sim time, including time that exposes them to the behavior of the aircraft in unusual scenarios that are specific to that model.
In this case, experiencing/simulating what the plane does in an extreme handling situation is not enough. They should need to experience what it is like not only when MCAS kicks in during the edge of stall. The training should also include the MCAS kicking in "out of the blue" during routine flight. This is a completely different experience with potentially very little time to react. If the plane pulls more than 1 negative G during this malfunction, it is going to be hard to even simulate. Reading a manual and sim might not even be enough, because of "instinctual" or automatic human response. Simulation is good, but now do it when you're cruising along with everything normal when the floor drops out from under you, you are disoriented, and the first and foremost thing being pressed onto your adrenaline soaked pea brain as you regain your orientation is the ground ending your life within the next 25 seconds unless you fix the problem within the first few of those seconds. And all the while you hear the screams of 200 passengers who are sure they're about to die through the cabin wall.

Military helicopter pilots are trained to evacuate the vehicle in a water crash, and the only effective simulation involves a giant tank of water and a fake helicopter that spins and dunks them upside down in the water. Apparently, only a small percentage of trainees make it out on the first try, even though they know exactly what is coming and when. This training greatly increased the survival rate of pilots in water landings. Simply knowing what to do and practicing under normal conditions did not help.
« Last Edit: March 19, 2019, 08:32:02 pm by KL27x »
 

Offline djacobow

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Re: Lion Air crash: Jakarta Boeing 737 'had prior instrument error'
« Reply #452 on: March 19, 2019, 09:06:38 pm »
But the thing is that flight manuals do not provide internalized models of how an airplane really flies. You have to get that from operating the machine. And furthermore, if you operate it carefully, within normal parameters associated with passenger flight, you won't get exposed to the extreme flight regimes where this knowledge is actually useful and important. So you can have 10,000 hours in a plane and still not know what it will do in an unusual situation. This *is* something you can learn in a simulator, if it is sufficiently faithful, and I think that is one learning that I think experts can already agree on regarding the MAX: the pilots should have gotten more sim time, including time that exposes them to the behavior of the aircraft in unusual scenarios that are specific to that model.
That is the whole point is it not? According to that eetimes article Boeing claimed that any experienced 737 pilot did not need additional training or simtime for the max.
That is also why it was a big seller, the airlines did not have to invest in hours of training and that was a massive saving. It is also probably in the future the reason that if there has to be substantial additional training, the airlines will cancel their orders.

Yes, that was the aircraft's goal and claim. And pilots are really trained these days to avoid the need for heroic mastery of ship's aerodynamics rather than trying to achieve such mastery. Today's pilots just don't have great stick and rudder skills, and that's turned out to be safe for the most part because other than trying to fly actually broken or malfunctioning aircraft, such skills rarely come up. They do, from time to time: USAir 1549, good outcome, AF447, bad outcome.

MCAS was designed to keep pilots from ever experiencing the instability of a MAX at extreme AOA. This was probably judged safer than trying to teach pilots to deal with it. Folks are saying that was not a sound engineering decision and I think they don't generally know what they're talking about. These are complex decisions, and history and human factors, and what can be expected of 1 std dev below mean pilots all figure into it.

But MCAS introduced a new failure mode (or modes) of its own, due to mistakes or poor enginneering, or reasons still unknown, and pilots have obviously not been able to handle that. The solution could be training on these failure modes or it could be fixing MCAS, or all of the above.

 
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Offline james_s

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Re: Lion Air crash: Jakarta Boeing 737 'had prior instrument error'
« Reply #453 on: March 19, 2019, 11:22:16 pm »
It seems to me they're going to end up needing additional training no matter what. Especially if these two accidents turn out to be caused by MCAS malfunctions, the pilots absolutely need to know what to do in the event that system fails and how to override it.

As far as stick & rudder skills, IMHO knowing how to deal with failures and fly by hand when necessary is exactly the reason we have professional pilots in the cockpit rather than an operator just skilled enough to monitor the automated systems. I worry that too much automation, not just in planes but now in cars too becomes a crutch, enabling people to become complacent and dependent on the technology and unable to step in when the technology inevitably fails in certain edge cases.
 

Offline tautech

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Re: Lion Air crash: Jakarta Boeing 737 'had prior instrument error'
« Reply #454 on: March 19, 2019, 11:52:33 pm »
Here in NZ pilot skills are assessed as in you're critiqued constantly by one another and have a few trips to the sim each year where assessment jumps to another level.
In the sim you're thrown all sorts of swerve balls and emergency situations that in particular the Captain must master.
Trouble is, if a particular situation is not able to be simulated pilots must refer to their basic flying skills in order to sort it out but if the plane is fighting them thinking it knows better, well Houston, we have a problem.
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Offline ogden

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Re: Lion Air crash: Jakarta Boeing 737 'had prior instrument error'
« Reply #455 on: March 20, 2019, 12:39:01 am »
MCAS was designed to keep pilots from ever experiencing the instability of a MAX at extreme AOA.

It was introduced for a reason - due to forward & up engine placement of MAX (compared to older models) which cause an upward pitching moment that leads to increased AOA and risk of stall. Some facts regarding Flight 302 are interesting: plane crashed with MCAS in "full nosedive mode", yet during last moments of flight plane gained altitude and speed according to flightradar24 data. Pilots have option to disengage automatic stabilizer trim and crank it mechanically using wheel, but seems that instead of taking control over MCAS, they simply fought it - continued to climb at full(?) throttle, reached high speeds with stabilizer in nosedive position and lost control over plane. [all this just speculation of armchair investigator]
« Last Edit: March 20, 2019, 12:50:47 am by ogden »
 

Offline Marco

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Re: Lion Air crash: Jakarta Boeing 737 'had prior instrument error'
« Reply #456 on: March 20, 2019, 01:58:28 am »
Pilots have option to disengage automatic stabilizer trim

An option they didn't think was relevant with the autopilot turned off.
 
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Offline djacobow

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Re: Lion Air crash: Jakarta Boeing 737 'had prior instrument error'
« Reply #457 on: March 20, 2019, 02:39:50 am »
Pilots have option to disengage automatic stabilizer trim

An option they didn't think was relevant with the autopilot turned off.

I don't think that's true. The trim wheels are moving by themselves. They are large and very obvious when turning. They also make a loud clacking. That is it dead obvious that the machine is retrimming the stab. You might not know why it is happening, but you know that it is. And the procedure to make it stop no matter the reason is simple. You don't need to know what subsystem is commanding the stab trim to disable it.

If the pilots wanted to disconnect the trim motors, they could have easily. That they didn't is a mystery that the CVRs will hopefully reveal. But I suspect the reason was that they weren't completely sure the machine didn't have a good reason to do what it was doing. They're trained to avoid stalls, and if the machine is saying down, down, down, you have to be really confident you know better to disconnect it entirely.
 

Offline Marco

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Re: Lion Air crash: Jakarta Boeing 737 'had prior instrument error'
« Reply #458 on: March 20, 2019, 03:39:32 am »
If the pilots wanted to disconnect the trim motors

That's a different switch though, the autopilot trim switch was in their mind irrelevant.
 
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Offline mtdoc

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Re: Lion Air crash: Jakarta Boeing 737 'had prior instrument error'
« Reply #459 on: March 20, 2019, 05:48:19 am »
Prediction:  The 737 Max will not fly again.
 

Online blueskull

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Re: Lion Air crash: Jakarta Boeing 737 'had prior instrument error'
« Reply #460 on: March 20, 2019, 05:57:57 am »
Prediction:  The 737 Max will not fly again.

400*125M$=50B$. Even 90% are reused in remanufacturing, that's still 4B$ cost. God bless Boeing.
 

Offline james_s

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Re: Lion Air crash: Jakarta Boeing 737 'had prior instrument error'
« Reply #461 on: March 20, 2019, 06:44:27 am »
I would bet it will be back in the air within a few months. Worst case they remove MCAS and re-certify, there appears to be nothing inherently wrong with the aircraft, it just handles a bit differently than the 737 classic. The DC-10 had teething problems that included several deadly crashes within a short period and went on to become a successful aircraft, along wit the MD-11 that evolved from it.
 
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Offline GeorgeOfTheJungle

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Re: Lion Air crash: Jakarta Boeing 737 'had prior instrument error'
« Reply #462 on: March 20, 2019, 08:56:37 am »
I would bet it will be back in the air within a few months. Worst case they remove MCAS and re-certify, there appears to be nothing inherently wrong with the aircraft
Problem is that it seems it is unstable and thats the reason for developing the MCAS.
As for the software update it doesn't matter what Boeing comes up with, it will be under harsh scrutiny of pilots, regulatory agencies and airlines worldwide. It may even make its way to Stackoverflow for discussion who knows ::).

It's not unstable, the only problem is the bug in MCAS that makes it push nose down relentlessly for no reason and crash, but not the dynamics of the plane.
The further a society drifts from truth, the more it will hate those who speak it.
 
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Offline GeorgeOfTheJungle

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Re: Lion Air crash: Jakarta Boeing 737 'had prior instrument error'
« Reply #463 on: March 20, 2019, 09:02:29 am »
Prediction:  The 737 Max will not fly again.

But that would be game over for Boeing...
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Offline Kjelt

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Re: Lion Air crash: Jakarta Boeing 737 'had prior instrument error'
« Reply #464 on: March 20, 2019, 09:07:17 am »
But that would be game over for Boeing... 
or the government would have to bail them out from US taxpayers money because it is an to important industry to loose like they did with some banks (so far for capitalism and each should hold up its own).
 

Offline tooki

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Re: Lion Air crash: Jakarta Boeing 737 'had prior instrument error'
« Reply #465 on: March 20, 2019, 09:41:26 am »
Prediction:  The 737 Max will not fly again.
There’s a precisely zero percent chance of this outcome.
 

Offline Kjelt

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Re: Lion Air crash: Jakarta Boeing 737 'had prior instrument error'
« Reply #466 on: March 20, 2019, 09:47:46 am »
Prediction:  The 737 Max will not fly again.
There’s a precisely zero percent chance of this outcome.
I would not be so sure.
The reputation of the name "737 Max" is already pretty much destroyed.
They might do some small alterations and rename the model to for instance 737 Plus or something like that, in that case mtdoc's prediction has become reality.
 

Offline Brumby

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Re: Lion Air crash: Jakarta Boeing 737 'had prior instrument error'
« Reply #467 on: March 20, 2019, 10:07:30 am »
Prediction:  The 737 Max will not fly again.
There’s a precisely zero percent chance of this outcome.
I agree.

I would not be so sure.
The reputation of the name "737 Max" is already pretty much destroyed.
They might do some small alterations and rename the model to for instance 737 Plus or something like that, in that case mtdoc's prediction has become reality.
That could always be a possibility - but I doubt it will go that far.  If Boeing bury the problem name and re-badge the airframe, it is going to be patently obvious as an attempt to hide the embarrassment.  I believe they need to brace themselves and take the flak head on - and I think it is clear they are going to cop some.
 

Offline Kjelt

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Re: Lion Air crash: Jakarta Boeing 737 'had prior instrument error'
« Reply #468 on: March 20, 2019, 10:25:22 am »
It is going to be interesting to see the "game" commence, who is going to resign, who is fired, who is getting the blame.
But in the end Airbus survived their computer-erroneous crashes, so I do not see why Boeing would be different.
 

Offline FrankBuss

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Re: Lion Air crash: Jakarta Boeing 737 'had prior instrument error'
« Reply #469 on: March 20, 2019, 10:27:04 am »
Some rumors about the audio recordings and flight data records:

https://www.reuters.com/article/us-indonesia-crash-exclusive/exclusive-cockpit-voice-recorder-of-doomed-lion-air-jet-depicts-pilots-frantic-search-for-fix-sources-idUSKCN1R10FB

In short: Looks like the nose was pushed down by the trim system and they didn't recognize it, and needed too long to read the manual how to fix it. The evening before another crew had the same problem, but they knew how to fix it, but apparently didn't tell the new crew about the problem.

Isn't there some regulation to report all problems, and for the new crew to read all reports? When I'm watching bus driver changing, they always ask and tell each other if there is a problem with the bus or on the route. I would have thought that's even more verbose for planes.
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Offline GeorgeOfTheJungle

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Re: Lion Air crash: Jakarta Boeing 737 'had prior instrument error'
« Reply #470 on: March 20, 2019, 10:44:17 am »
No doubt, the pilots are to blame too. After the 610 flight crash they should have known better and disable the damn thing at the first sign.
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Offline ogden

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Re: Lion Air crash: Jakarta Boeing 737 'had prior instrument error'
« Reply #471 on: March 20, 2019, 11:04:34 am »
It's not unstable, the only problem is the bug in MCAS that makes it push nose down relentlessly for no reason and crash, but not the dynamics of the plane.

I beg to differ, The software was designed to compensate for a new instability that resulted from some small physical-design modification and MCAS was added to comply with airworthiness certification

Exactly. Pushing nose down to decrease AOA and avoid stall is function of MCAS, not bug. Main question here is: it was bad decision of MCAS due to faulty AOA sensor or bad decision of pilots to fight MCAS or maybe both. If instruments scream that stall is imminent, plane itself is pushing nose down to decrease AOA but you gain altitude and speed instead (thus increase AOA) - it is very strange thing to do to say it politely.

[edit] Who the hell runs life-critical system from input of just two sensors single sensor?! - Even automobile airbags have better redundancy (AFAIK).
« Last Edit: March 20, 2019, 03:50:58 pm by ogden »
 

Offline Kjelt

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Re: Lion Air crash: Jakarta Boeing 737 'had prior instrument error'
« Reply #472 on: March 20, 2019, 11:36:40 am »
 

Offline LapTop006

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Re: Lion Air crash: Jakarta Boeing 737 'had prior instrument error'
« Reply #473 on: March 20, 2019, 11:59:21 am »
The reputation of the name "737 Max" is already pretty much destroyed.

Nah. You'd still fly on a 787 despite the battery fires?

The 777 with engine icing?

What about a DC10 (ok, the final ones are now out of passenger service) after all the cargo door incidents?

The earlier 737s with rudder hard-over?

These things happen with new models, and are usually fixed.

As others have said, the 737MAX is a bit of a hack to keep the line going to compete with the re-engined A320 series, Boeing's plan was to do a fresh design so they could throw away a bunch of the legacy the 737 type certificate, but they decided that would give them a risk of losing customer to Airbus.

Their big hope in this space is probably the MOM airplane plan goes very well, enough to justify a shrink variant that would fit in 737 gates and share a type certificate (similar to the 757/767 days).
 
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Offline Bud

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Re: Lion Air crash: Jakarta Boeing 737 'had prior instrument error'
« Reply #474 on: March 20, 2019, 01:15:34 pm »
Both planes crashed in presumably hot climate. Could that have to do with the angle of attack sensors failing?
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