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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'

#231

Post by femto113 »

xmeyers wrote: post #27
matt4077 wrote: post #17

Earlier quoted context omitted.

Airline safety has increased by a factor of 100 in the last 50 years, in terms of fatalities / miles travelled. Both in the past and now, far more accidents are the result of pilot error than failure of any system. Gloryfing the good old days of pilot jocks just isn’t supported by the actual data, this incident nonewithstanding.

Isn't that orthogonal to the previous statement? The ideal situation would be to have fly-by-wire and a single hands-off button instead of HAL saying "Sorry Dave, but I cannot do that". Of course, commercial pilots would need to have an actual interest in flying manually. The Gimli glider pilot was an enthusiastic pilot outside professional aviation. I don't know if such an interest is still possible with modern expl…

I’d go beyond an “off switch” and argue that any software that’s smart enough to turn itself on without being asked needs to turn itself off if it’s obvious that the pilot is fighting against it. It’s like a classic Bayesian probability problem where the chance of a false positive is high. The software has to take into account that the stall scenario it thinks is happening is rare, and that happening followed by a pilot yanking back on the stick is vanishingly rare, accept that it was probably wrong and undo its actions.

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

#232

Post by treis »

JshWright wrote: post #198
sokoloff wrote: post #193

Earlier quoted context omitted.

IMO, no. There is a released fact (via photographs) that the jackscrew on the stab trim was run to the extreme. That's strong evidence to suggest that the non-normal checklist for stab trim runaway was not correctly followed. The aviation minister's comment today does not carry weight in excess of the photographic, factual evidence, IMO. There are too many "loopholes" that she could be exploiting without leaving her…

The explanation put forward (which seems reasonable) is that the cutouts were disengaged because the aerodynamic forces were stronger than could be overcome by the manual control, so they had to turn the electrics back on in an attempt to move it (which allowed the MCAS to continue pushing the stabilizer to the extreme)

>The explanation put forward (which seems reasonable) is that the cutouts were disengaged because the aerodynamic forces were stronger than could be overcome by the manual control, so they had to turn the electrics back on in an attempt to move it (which allowed the MCAS to continue pushing the stabilizer to the extreme)

But the only way it would end at the total extreme is if they were within 2.5 degrees of max when they re-enabled electric trim and they crashed within 5 seconds. Otherwise, they should have been able to at least get some adjustment.

>Boeing’s anti-stall software on a doomed Ethiopian Airlines jet re-engaged up to four times after the crew initially turned it off due to suspect data from an airflow sensor, two people familiar with the matter have said.

https://www.theguardian.com/business/2019/apr/03/ethiopian-a...

4 cycles should have gotten them to 7-10 degrees away from the extreme. So something else was going on.

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

#233

Post by DanielBMarkham »

carbocation wrote: post #199
DanielBMarkham wrote: post #42

Earlier quoted context omitted.

I really didn't want to flame the room. As a commercially-rated small plane pilot and coder, I have a passion here and it both hurts me and makes me really angry. I said this was a programmers problem, not a software problem, and I identified one of the key causes as programmers being isolated from user outcomes. Probably not a big deal if your user can't get to the website for 10 minutes. Different thing entirely he…

I agree with much of what you say here. I don’t agree that programmers are at fault or are particularly well suited or intervene, since the core is not a software problem. This is the nature of systems problems. Nevertheless, I think that we have a core agreement.

I wrote this two years ago -- the first chapter of a book (which I'm trying really hard _not_ to pump here)

https://wiki.info-ops.org/index.php/Main_Page#Info-Ops

There's a link to the first ten pages.

I find it difficult to write an intro like that and then see this happen again.

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

#234

Post by LoSboccacc »

School-Cotton wrote: post #142
LoSboccacc wrote: post #29

Earlier quoted context omitted.

there is a manual override but once you are fully trimmed down manually trimming up takes time and time is something you don't have much of with the plane pitching down near the ground.

If it takes too long to adjust trim to a desired position, why can’t the pilots still pitch up by pulling back on the yoke?

the control surfaces have less authority than the trim. original spec called for less mcas authority, but it was increased later without much consideration.

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

#235

Post by dingaling »

VBprogrammer wrote: post #132
dingaling wrote: post #110

Earlier quoted context omitted.

A bad AoA probe wouldn't trigger IAS disagreement alert ( that is fed from the separate pitot tubes ) but could activate the corresponding stick-shaker which may make the pilots consider the possibility of IAS uncertainty. Just a minor quibble. Also increasing airspeed isn't a panacea for avoiding a stall, it is entirely possible to enter a high-speed stall if the AoA isn't managed. And in fact as mentioned speed can…

From the AD issued after the Lion Air accident: Additionally, pilots are reminded that an erroneous AoA can cause some or all of the following indications and effects: - Continuous or intermittent stick shaker on the affected side only. - Minimum speed bar (red and black) on the affected side only. - Inability to engage autopilot. - Automatic disengagement of autopilot - IAS DISAGREE alert. - ALT DISAGREE alter. - AO…

Thank you for the corrections!

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

#236

Post by dralley »

CaptainZapp wrote: post #130
throwaway29875 wrote: post #72

Earlier quoted context omitted.

I'm really surprised they didn't go ahead and blame the pilot's "ethnic culture" like the did with Asiana 214 [1] 1. https://www.cnbc.com/id/100869966

I'm extremely critical with Boeing's responses in general and the smearing and throwing pilots and airlines under the bus. But in that case they had a point. Seniority is super important in Asian culture. You just! don't! criticize! your! superiors! period. That's extremely diametral for resources management and crew communication in a cockpit. The first officer may tend to say nothing, even if he believes the plane…

The actual vocabulary used when speaking to superiors in many asian languages also tends to be more verbose and subdued in meaning, as opposed to sharp and concise.

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

#237

Post by VBprogrammer »

simion314 wrote: post #158
agmiller wrote: post #136

Earlier quoted context omitted.

Pilot error is always assumed for pilots of all races. The French pilot who was allegedly responsible for crashing an Airbus during a flyover for an air show fought decades for clearing his name. He also claimed that the system had "artificial stupidity", that was the time when pilots first had the fun of encountering the many Airbus "flight laws".

But in this case the pilots and airlines were accused to be a lower tier then the american pilots. So on top of the regular accusations if this would have been an american airplane the third world country accusations were added on top as an extra.

There was definitely an air of superiority of American pilots. The problem is that there is a grain of truth to it.

A big part of this is that the American Airforce train a huge number of pilots to an incredibly high standard who eventually leave the military and become civilian pilots. Any pilot who isn't naturally gifted in the art of flying an aeroplane will be flunked before finishing their training. They are tested in ways that a 200 hour civilian CPL just never will be.

Even the increasing numbers of pilots coming to flying through a civilian tract in the US have a number of benefits. Classically they flew cancelled cheques around the US in beaten up twin engine aircraft in all weathers while building the required number of hours. Even in modern times, due to a culture of GA flying, they've got a lot more opportunities to fly different aircraft types (taildragger, floatplanes, gliders), fly aerobatics etc.

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

#238

Post by danielg6 »

Yetanfou wrote: post #226
calcifer wrote: post #202

Earlier quoted context omitted.

"I don't see colour, it's not about race" said the white Western European guy...

You're implying I am 'white', 'western-European' and '[a] guy' even though this is irrelevant and there is no indication of either my race, origin or sex in my post. Please stop doing that, it only serves to create strife where no strife is needed. It is almost as if you did not read the comment you responded to or - worse - decided to ignore it because it does not fit a given narrative.

You didn’t read through or even skim the hundreds of comments on the other HN posts. And don’t tell me about the policy saying not to tell people they didn’t read the article or whatever it is. You didn’t read them. If you did, you wouldn’t have used the phrase “Stop looking for racism”. There were many comments where people explicitly said racist and xenophobic things. There’s nothing to “look for” when it’s explicitly stated...

You even used the word “explicit” yourself...

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

#239

Post by School-Cotton »

LoSboccacc wrote: post #234
School-Cotton wrote: post #142

Earlier quoted context omitted.

If it takes too long to adjust trim to a desired position, why can’t the pilots still pitch up by pulling back on the yoke?

the control surfaces have less authority than the trim. original spec called for less mcas authority, but it was increased later without much consideration.

I see, thanks for the info.

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

#240

Post by 7952 »

simion314 wrote: post #158
agmiller wrote: post #136

Earlier quoted context omitted.

Pilot error is always assumed for pilots of all races. The French pilot who was allegedly responsible for crashing an Airbus during a flyover for an air show fought decades for clearing his name. He also claimed that the system had "artificial stupidity", that was the time when pilots first had the fun of encountering the many Airbus "flight laws".

But in this case the pilots and airlines were accused to be a lower tier then the american pilots. So on top of the regular accusations if this would have been an american airplane the third world country accusations were added on top as an extra.

It is hard to imagine how any 737 pilot would be unaware of the problem and resulting Boeing advice given the massive amount of attention this has reviewed. Regardless of training issues I find it hard to believe that any pilot would be so indifferent as to ignore this.
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