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Ethiopian Airlines Boeing 737 pilots 'could not stop nosedive'

bbc.co.uk

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Re: Ethiopian Airlines Boeing 737 pilots 'could not stop nosedive'

#161

Post by sokoloff »

SmellyGeekBoy wrote: post #144
sokoloff wrote: post #137

Earlier quoted context omitted.

Pilot error is the leading cause of airplane crashes. If someone offers you an even money wager that pays you if the next crash will have pilot error as a significant cause, take the wager. I am at least twice as likely to kill my airplane than my airplane is to kill me.

How many accidents blamed on "pilot error" are a result of the pilot not being given enough information to make the right decision, or given the wrong information? I'm not saying that pilots are completely faultless but if they're making mistakes we should look to improve the systems and procedures that allow them to make the right decisions, not start pointing fingers.

I agree with CaptainZapp’s comments next to this one.

The process you describe does happen, but IMO, clearly articulating the facts and assigning findings of probable cause (the latter is what you term pointing fingers) is an essential element of that improvement process.

The is a strong safety culture in aviation overall. It’s rare for one isolated mistake to result in a hull loss, but rather is usually a series of issues where the “holes in the Swiss cheese all line up”.

No doubt Boeing and others are going to improve technical and human factors elements from this crash. It doesn’t help anyone in this process to not assign probable cause, IMO.

Re: Ethiopian Airlines Boeing 737 pilots 'could not stop nosedive'

#162

Post by VBprogrammer »

peteradio wrote: post #154
VBprogrammer wrote: post #73

Earlier quoted context omitted.

The official report will make for interesting reading. The speculation over the last few days is starting to fill in some questions I've had: - Why didn't the pilots identify the issue as MCAS malfunction and follow the guidence? They did and it didn't work for some reason. Possibly because of the air loads on the stabilizer. - Why did the AoA sensor on a new aircraft fail? Suspected bird strike.

Why is nobody looking at the manufacturer of the sensor?

If someone connected a big industrial stop switch to a solenoid and pointed that solenoid at the trigger of a rifle aimed at the person pressing the button I don't think you would expect anyone to look particularly hard at the person who manufactured the switch.

If it was indeed a bird strike which took out the sensor then they seem to be completely beyond all possible blame. Even if it wasn't I'm sure they could point at a host of documentation regarding the usual MTBF of their sensors and why this application was inappropriate.

Re: Ethiopian Airlines Boeing 737 pilots 'could not stop nosedive'

#163

Post by VBprogrammer »

woofcat wrote: post #151
VBprogrammer wrote: post #73

Earlier quoted context omitted.

The official report will make for interesting reading. The speculation over the last few days is starting to fill in some questions I've had: - Why didn't the pilots identify the issue as MCAS malfunction and follow the guidence? They did and it didn't work for some reason. Possibly because of the air loads on the stabilizer. - Why did the AoA sensor on a new aircraft fail? Suspected bird strike.

- They did and it didn't work for some reason. Possibly because of the air loads on the stabilizer. Has the CVR transcript been released? I can't find any source on the procedures taken in the cockpit prior to the crash.

I believe the media have been briefed on the the contents of the report but it isn't yet publicly available. It's annoying because I don't trust the media to get the details correct on this type of thing.

Re: Ethiopian Airlines Boeing 737 pilots 'could not stop nosedive'

#164

Post by CaptainZapp »

matt4077 wrote: post #159
swiley wrote: post #127

Earlier quoted context omitted.

You really shouldn’t ever trust the NYT. They haven’t been trustworthy for a while.

Their report merely states that a simulator was available, and that the crew did not train it it. It even includes the fact that Boeing did not consider such training necessary. How is it untrustworthy to report these uncontested facts? You are drawing a conclusion that the article does not make, namely that the lack of simulator use was the singular cause of the accident. It takes some gall to accuse the Times of a…

My bad. It was me drawing the conclusion.

And granted: That was mainly from the headlines, which were also picked up by other publications.

I would remove my comment, but that kills the flow of the thread so I let it stand and apologise for my making the unfounded comment.

I was under the impression (probably not unreasonable if you look at Boeing's reaction in the last few weeks) that the company was actively smearing the pilots and using their press connections to actively do that.

Mea culpa!

Re: Ethiopian Airlines Boeing 737 pilots 'could not stop nosedive'

#165

Post by treis »

CaptainZapp wrote: post #122
matt4077 wrote: post #12

I’d love to see those people who accused the airline and crew of being incompetent to apologize in the light of these reports. It was shameful to see Boeing actively encouraging that narrative behind the scenes. Especially considering it plays on racist stereotypes equating „Africa“ with bad training/bad safety record/…. The idea of „dingy third world airline“ was ridiculous on its face, considering how bad a fit fly…

Totally agree. Some of the sentiments expressed here was borderline racist. (badly trained, overworked cluelless third world pilots not even capable to follow a checklist). One of the worst smear jobs was actually by the New York Times accusing the captain of the Ethiopian plane not having trained in a 787-MAX simulator. Hello? Wasn't that the whole sales pitch that the plane requires no training at all for certified…

>the Lion Air crash (they were busy smearing the airline an the pilots instead)

In a rush to put to blame on Boeing everyone seems to have forgotten that Lion Air badly screwed up:

(1) The aircraft exhibited the same failure on its previous flight. Not fixing it before the next flight is a huge maintenance screw up.

(2) That failure and the steps to correct it should have been in the log book and the next pilots should have been keenly aware of the potential issue and how to fix it

(3) The pilots counteracted MCAS some 20 times by using the electronic trim control but never switched over to manual control.

A better designed plane might not have tested the mettle of Lion Air as sternly as this issue did. However, that doesn't change that the fact that when tested the pilots and Lion Air performed terribly.

It wasn't just Boeing defending their plane. Pilots unions also came out and said that they saw no issue with the plane and that their members felt like they could handle any issue.

Re: Ethiopian Airlines Boeing 737 pilots 'could not stop nosedive'

#166

Post by peteradio »

kharms wrote: post #125
Slartie wrote: post #44

Earlier quoted context omitted.

I am pretty sure the software here did exactly what it was supposed to do. There was no buffer overrun, no NullPointerException, not any other kind of bug. There was just software that reacted exactly as specified. The problem is: those specifications were bad. It's a bad idea to just rely on one single sensor when you actually have two, it's a bad idea to write software that disengages on manual input counteracting…

Bad programming was not the sole or root cause but it was a cause, and people died. You can't punt on that unless you want software engineer to actually mean code monkey. The same way a building architect has to sign off on the design demands of a a client, a software engineer on safety-critical systems must evaluate the spec and consider the effects of edge cases.

What do you suppose the spec was here and how did the Engineer neglect to fulfill it? These specs are very compartmentalized, you think the Engineer is responsible for the big picture understanding and gets to take it up with the VP? No.

Re: Ethiopian Airlines Boeing 737 pilots 'could not stop nosedive'

#167

Post by hammock »

Shank wrote: post #160
alkonaut wrote: post #145

Earlier quoted context omitted.

I'm an armchair non-expert at best: but shouldn't planes always be controllable by the column so long as the plane is mechanically OK? I.e. max power + pull stick should always just take the plane up, regardless of any amount of misconfiguration such as being out-of-trim etc? Isn't that a reasonable expectation? That is: a pilot in panic at low altitude should never be required to do anything more than he basically c…

> but shouldn't planes always be controllable by the column so long as the plane is mechanically OK? The problem is that you can easily exceed the aircraft flight specifications if you enable unlimited control. If you pull the stick back at max power you can seriously risk the creation of a stall, which is why MCAS exists in the first place. The whole goal Boeing had was to create a safe plane by letting software ens…

>what makes the determination that the pilot is at a low altitude?

Give the pilot an emergency override button and let him make the judgment call. The whole point of parent comment is that too many sensors and software have removed the pilot's final discretion over the aircraft.

Re: Ethiopian Airlines Boeing 737 pilots 'could not stop nosedive'

#168

Post by phire »

batat wrote: post #85
deepstream wrote: post #11

pilots should not have to fight the system. can there not be a simple button, "switch to manual"?

MCAS can be disabled, but pilots says this may not help in some situations: > On the simulator when the stabilizer was "on a dive" at maximum angle, me and my colleagues weren't able to recover a plane. > If you follow Boeing bulletin, but start the procedure too late, it will only make things worse. Simpler solution (in case of problems right after takeoff) is to release the flaps at least to the first position. Thi…

MCAS can't really be disabled.

They procedure just disables the electric motor that MCAS is using to adjust the trim down. MCAS will still be sitting there sending trim down commands that get ignored.

Problem is, that electric motor is used by the manual trim adjust buttons too, so they stop functioning too. Following the procedure results in a nose down trim that pilots have to correct by manually turning the trim wheel, and it turns out the aerodynamic forces may be too strong for that procedure.

Re: Ethiopian Airlines Boeing 737 pilots 'could not stop nosedive'

#169

Post by mic47 »

skrebbel wrote: post #91
jakecopp wrote: post #58

Earlier quoted context omitted.

Hard engineering problem - where do you open up the fuselage to get the people out? It's a tube so you can't weaken it. You also can't open a hole at the back and let them slide out backwards, you'd need a cylindrical tube in a tube which can then slide out. That's a HUGE amount of extra weight and complexity. Planes are so so much safer than cars. Before we parachute people out of passenger planes we should be eject…

> Before we parachute people out of passenger planes we should be ejecting people out of the roofs of cars if an imminent collision is detected :) I'd be "accidentally" driving into a lot of trees if cars had that. Sounds like major fun!

Imagine this happening in the tunnel

Re: Ethiopian Airlines Boeing 737 pilots 'could not stop nosedive'

#170

Post by matt4077 »

peteradio wrote: post #154
VBprogrammer wrote: post #73

Earlier quoted context omitted.

The official report will make for interesting reading. The speculation over the last few days is starting to fill in some questions I've had: - Why didn't the pilots identify the issue as MCAS malfunction and follow the guidence? They did and it didn't work for some reason. Possibly because of the air loads on the stabilizer. - Why did the AoA sensor on a new aircraft fail? Suspected bird strike.

Why is nobody looking at the manufacturer of the sensor?

For reasons similar to those often cited not to blame a single operator when they accidentally drop the production database.

It seems these sensors, and also pitot tubes, are notoriously unreliable. That is likely to be function of them being mechanical (moving parts) systems in rather unaccomodating environments, I. e. freezing cold, strong winds, etc.

In such a scenario, one has to acknowledge the shortcomings, instead of denying them and expecting unreachable perfection. That means building systems that expect failure and have enough redundancy to mitigate them.

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