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Pilot Who Hitched a Ride Saved Lion Air 737 on the Day Before Deadly Crash

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Re: Pilot Who Hitched a Ride Saved Lion Air 737 on the Day Before Deadly Crash

#171

Post by cjbprime »

snowwindwaves wrote: post #165
cjbprime wrote: post #155

Earlier quoted context omitted.

This is grossly overstating the optional feature. As I understand it, "AOA disagree" is a single light near the AoA indicator itself. It's not an explanation, or even an alert. It's not where anyone would reasonably look when trying to diagnose an uncommanded flight control problem.

When lights are normally not lit and one lights up a pilot or other machine or plant operator should take notice. A detailed explanation should not be required since they should know what the different warning lights mean and what can cause them to be lit. I personally would like to see a list of the airlines that bought the more expensive 737 max that included the additional safety features.

The North American airlines bought it and no others did. It was not described as a safety feature -- if it was it wouldn't be permissible to make it optional.

Even the current training does not tell pilots to know that an AoA disagree light is an emergency because it can cause the plane to enter an uncommanded nosedive via MCAS. I really don't think it's reasonable to expect the pilots to know things that Boeing is not even trying to tell them.

Re: Pilot Who Hitched a Ride Saved Lion Air 737 on the Day Before Deadly Crash

#172

Post by adontz »

cameldrv wrote: post #144
js2 wrote: post #125

Earlier quoted context omitted.

Can you explain how they are different? Both cause the stabilizer to tilt. Both cause the stabilizer wheels next to the pilot/co-pilot to turn. If the plane is pitching down, and you pull back the yoke and that still doesn't recover, don't you at some point check the stabilizer angle? If it's wrong, you use the stabilizer trim switch on the yoke under your thumb to correct it. Won't you see the stabilizer wheel turn…

My guess would be perspective, two kinds. First he’s gonna be behind the throttle quadrant. The stabilizer wheels are roughly in the center of his vision, so he will notice them moving and when they start and stop. The pilots have them down near their thighs, so they’re not even necessarily in their peripheral vision. They will be less likely to notice every time they start and stop. Second the jumpseat guy has no fl…

Pilot priorities are: aviate, navigate, communicate. If you listen to incident recordings often pilots tell tower to wait and do not respond immediately. So radio calls are always low priority compared to actual flying. But I agree with point of view argument.

Re: Pilot Who Hitched a Ride Saved Lion Air 737 on the Day Before Deadly Crash

#173

Post by cjbprime »

cryptonector wrote: post #168
cjbprime wrote: post #154

Earlier quoted context omitted.

That.. sounds like the literal opposite of what it shows, no?

I think you misunderstood. Had the pilots been trained, they could have dealt with it -- that the off-duty pilot was able to shows it was possible to respond correctly, while that the others weren't shows the lack of training is a real problem.

Thanks, I see. I don't think it does much good to notice that a small percentage of pilots can be capable of figuring it out, if they have no other duties at the time.

That doesn't tell us that it's reasonable to expect pilots in command under stress to always figure it out. And they have to figure it out 100% of the time to avoid statistically unacceptable crashes. So I don't agree that pilot training is an acceptable answer given what we know so far.

Re: Pilot Who Hitched a Ride Saved Lion Air 737 on the Day Before Deadly Crash

#174

Post by averros »

zaphirplane wrote: post #106
Someone1234 wrote: post #91

Earlier quoted context omitted.

It didn't need to be included in the preliminary report since it is contextual/background information. They did include in the report that on a previous flight the same sensor error occurred and the pilots resolved it by disabling auto-trim. The fact there was a third pilot there is definitely interesting, but they didn't make anyone less safe by not including it in the report. There's no bombshell here. Previous pro…

This is very important, as it shows the ratio of pilots aware of the mitigation is low, and/or the stress of fighting with the the computer makes you forget you training amendments Edited to add it’s a training amendment

Actual instrument-rated pilot here.

What people (including pilots) do under stress is resort to simple actions drilled in by training. That's why emergency procedure training is a major part of pilot training curriculum.

What goes away first under stress is capability for complex reasoning, which is what one would need to figure out what the heck is going on and take appropriate action. In this case an a/c doing uncommanded dive can be a result of three things: elevator controls malfuncion (unlikely in modern jets, the mechanisms for transmitting control forces from the yoke to the elevator are multiply redundant and well-understood to be critical), structural breakdown (empennage falling off would do that), or run-away elevator or stabilizer trim.

In most a/c the runaway trim can be only caused by malfunctioning auto-pilot (that's why APs have multiple redundant ways to disable them), so the pilots faced this situation react by trying to disable AP in all available ways and then immediately jumping to conclusion that there's something catastrophically wrong with elevator system or even airframe integrity. The thought that there could be yet another system which can do major trim adjustment doesn't even enter their consciousness.

Training (and/or being in a position where there's no immediate stress of wrangling misbehaving a/c) would help to get to the correct solution (disabling trim motor by pulling the circuit breaker).

That said, flying an a/c seriously out of trim is hard, and can cause an accident on its own (the fine pitch control is gone, and you can even be so far out of trim that you cannot do landing flare no matter how hard you pull up, which in heavy jets would result in structural breakdown when the plane slams into runway).

Re: Pilot Who Hitched a Ride Saved Lion Air 737 on the Day Before Deadly Crash

#175

Post by briandear »

cryptonector wrote: post #138
Someone1234 wrote: post #94

Earlier quoted context omitted.

Boeing offered that, but it was a paid extra that few airlines purchased. https://theaircurrent.com/aviation-safety/southwest-airlines...

Yeah, maybe it shouldn't be an extra.

> The Indonesia safety committee report said the plane had had multiple failures on previous flights and hadn’t been properly repaired.

It probably wouldn’t have mattered. Lion Air couldn’t even maintain their planes properly; assuming an extra indicator would help would be charitable at best.

Re: Pilot Who Hitched a Ride Saved Lion Air 737 on the Day Before Deadly Crash

#176

Post by arcticbull »

hencq wrote: post #143
arcticbull wrote: post #126

Earlier quoted context omitted.

It's a single data point / anecdote. These investigations are incredibly thorough, precise, and authoritative so it makes sense they'd seek to exclude that kind of information until they knew for sure.

I'm not sure that thorough and precise implies they would seek to leave out things. In fact, one would expect the opposite.

One data point may lead you to bad conclusions, like in this case "one third of pilots don't know how to disengage the MCAS" -- the fact is we don't know what ratio. It might be higher, it might be lower, but one data point isn't valuable or thorough. In the preliminary report they mentioned someone else disabled it. In their final, I'm sure we'll get the details.

Re: Pilot Who Hitched a Ride Saved Lion Air 737 on the Day Before Deadly Crash

#177

Post by gmoot »

js2 wrote: post #119
Someone1234 wrote: post #116

Earlier quoted context omitted.

US pilots say they didn't either. The training wasn't out there.

The runaway stabilizer trim procedure is how it was expected to be handled: https://www.flightglobal.com/news/articles/faa-order-tells-h... https://www.youtube.com/watch?v=3pPRuFHR1co The specifics of MCAS weren't out there because Boeing expected the pre-existing procedure to have been sufficient. That procedure wasn't sufficient, or the Lion and Ethiopian Air pilots were somehow not aware of it, or they forgot thei…

somehow the pilots were able to bring the nose back up... it was only (apparently) after multiple nose downs that they eventually failed to recover the plane. What was going on there?

The MCAS activated several times, each time ratcheting the stabilizer down by 2.5 degrees. Every time the pilots tried to correct for it, it would engage again. That is what caused the characteristic up/down flight pattern.

There are a lot of details in this story: https://www.seattletimes.com/business/boeing-aerospace/faile...

Re: Pilot Who Hitched a Ride Saved Lion Air 737 on the Day Before Deadly Crash

#178

Post by briandear »

> The Indonesia safety committee report said the plane had had multiple failures on previous flights and hadn’t been properly repaired.

Lots of blame for Boeing, but the real criminals are Lion Air who apparently don’t know how to maintain airplanes. Compare their safety record with Southwest Airlines. Lion Air shouldn’t be allowed to fly.

Re: Pilot Who Hitched a Ride Saved Lion Air 737 on the Day Before Deadly Crash

#179

Post by jimktrains2 »

platinumrad wrote: post #19
jnbiche wrote: post #11

...

>In fact, I thought these crash recovery systems had to be written by 3 different teams in 3 different languages or architectures, and only activate when 2 of the 3 signal true. Or there's some manufacturer that does avionic software like this, I forget who. Redundant systems with majority voting are common, and this can include multiple implementations of the same spec, but I'm not aware of any manufacturer that int…

I don't know about 3 languages, but https://www.fastcompany.com/28121/they-write-right-stuff implies that there is software written by at least two different groups running on the shuttle.

I've also heard anecdotally that some train signalling and on-board control systems run software simultaneously in linuc and freebsd to oessen the chance of simultaneous memory faults. (I didn't get a chance to ask for more details or clarification.)

Re: Pilot Who Hitched a Ride Saved Lion Air 737 on the Day Before Deadly Crash

#180

Post by tluyben2 »

raihansaputra wrote: post #50

There's a thread on twitter with a pretty good analysis of what's happening with 737MAX. The 'Swiss Cheese' model here starts from its redesign by Boeing. https://twitter.com/trevorsumner/status/1106934362531155974

From all I read; this including the optional disagree indicator, I still say Boeing is should be held responsible for this: all point to economic reasons which means they decided these things and fully knew the potential consequences.
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