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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'

#241

Post by mhandley »

mhandley wrote: post #7

Will be interesting to see the details when the report is actually public. It does sound like the scenario that Mentourpilot explored in the simulator is close to what happened, namely: Bad AoA probe causes MCAS to trim down, and also to indicate IAS disagree. Pilots increase throttle as per non-normal checklist to reduce the risk of stalling due to unreliable airspeed. Pilots disable electric stabilizer trim, as per…

Official report is now out: http://www.ecaa.gov.et/documents/20435/0/Preliminary+Report+...

This scenario does indeed appear to be what happened. It just looks like when they re-enabled electric trim, they didn't trim up enough, and then left it turned on. 5 seconds later, MCAS kicked in again, and then it was all over.

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

#242

Post by cameldrv »

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 first officer on that flight was extremely inexperienced. He only had 200 hours of total flight time. In the U.S., you need 1500 to sit in the right seat of an airliner in scheduled service. While I would not put the blame on the pilots for the accident, it's impossible to know if it might have turned out differently had there been two experienced pilots in the cockpit.

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

#243

Post by treis »

mhandley wrote: post #241
mhandley wrote: post #7

Will be interesting to see the details when the report is actually public. It does sound like the scenario that Mentourpilot explored in the simulator is close to what happened, namely: Bad AoA probe causes MCAS to trim down, and also to indicate IAS disagree. Pilots increase throttle as per non-normal checklist to reduce the risk of stalling due to unreliable airspeed. Pilots disable electric stabilizer trim, as per…

Official report is now out: http://www.ecaa.gov.et/documents/20435/0/Preliminary+Report+... This scenario does indeed appear to be what happened. It just looks like when they re-enabled electric trim, they didn't trim up enough, and then left it turned on. 5 seconds later, MCAS kicked in again, and then it was all over.

It sounds like they did almost everything right. There are two fateful moments:

>At 05:41:46, the Captain asked the First-Officer if the trim is functional. The First-Officer has replied that the trim was not working and asked if he could try it manually. The Captain told him to try. At 05:41:54, the First-Officer replied that it is not working

At this point they were in stable flight and the trim wasn't that extreme. It's not clear whether "manually" here means manual electric trim or trying to physically turn the trim wheel. Up until this point they had correctly diagnosed the issue and taken the proper steps.

>At 05:43:11, about 32 seconds before the end of the recording, at approximately 13,4002 ft, two momentary manual electric trim inputs are recorded in the ANU direction. The stabilizer moved in the ANU direction from 2.1 units to 2.3 units. >At 05:43:20, approximately five seconds after the last manual electric trim input, an AND automatic trim command occurred and the stabilizer moved in the AND direction from 2.3 to 1.0 unit in approximately 5 seconds. The aircraft began pitching nose down. Additional simultaneous aft column force was applied, but the nose down pitch continues, eventually reaching 40° nose down. The stabilizer position varied between 1.1 and 0.8 units for the remainder of the recording.

They re-activated electric trim control but only slightly adjusted it. MCAS kicks in to send them nose down. There's no further pilot correction recorded. Unclear here if there is an airplane issue preventing them from adjusting trim or a pilot error.

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

#244

Post by sokoloff »

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)

Ah. They'd have had to "roller coaster" the airplane (pitch up, then move the elevator surface towards neutral [so a net nose down]) to get the trim to move manually [the last step on the checklist]. Repeat as needed until the stab is trimmed within a range where it can move manually in unaccelerated flight.

That's an interesting possibility, which if they didn't know about it (I don't blame them), they may have felt they had no choice but to go "off checklist" and re-engage the electric trim system. I'd expect that would be in the context of "PF commands nose up pitch trim continuously while PNF engages the trim cutout to normal and monitors."

That's a tougher hand dealt the crew than I previously contemplated and if that's what they did, it's one for which I will owe them a retraction.

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

#245

Post by tarabanga »

sokoloff wrote: post #129
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…

I am one of those people. If in fact the stab trim cutout switches were set to cutout early in the incident sequence, as required by the memory items on the checklist, I will absolutely retract my criticism of the crew and the blame falls much more squarely/exclusively on Boeing. I’ll make it a point to retract and apologize on all three forums where I made those comments (two tech and one aviation). I don’t read the…

> The crew performed runaway stabilizer checklist and put the stab trim cutout switch to cutout position and confirmed that the manual trim operation was not working

This is on page 25 of the report.

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

#246

Post by mhandley »

treis wrote: post #243
mhandley wrote: post #241

Earlier quoted context omitted.

Official report is now out: http://www.ecaa.gov.et/documents/20435/0/Preliminary+Report+... This scenario does indeed appear to be what happened. It just looks like when they re-enabled electric trim, they didn't trim up enough, and then left it turned on. 5 seconds later, MCAS kicked in again, and then it was all over.

It sounds like they did almost everything right. There are two fateful moments: >At 05:41:46, the Captain asked the First-Officer if the trim is functional. The First-Officer has replied that the trim was not working and asked if he could try it manually. The Captain told him to try. At 05:41:54, the First-Officer replied that it is not working At this point they were in stable flight and the trim wasn't that extreme…

When they did that final electric trim up, the right (more reliable) ASI indicates 365 knots. VMO is 340, so they were already in real trouble. It's not at all clear that even electric trim could overcome the air loads at that point to trim up, though it does look from the graph like it responded slightly.

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

#247

Post by simion314 »

VBprogrammer wrote: post #237
simion314 wrote: post #158

Earlier quoted context omitted.

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 tes…

So, do you know as a fact that plots in other countries are less passionate or have less training?

It would be interesting if you have a source of how many civilian pilots are ex-military pilots, as an non-expert I would say that having experience with a fighter plane is not better then having same hours of experience with a civilian plane, it is not like fighter plane experience is much better then other planes when considering you will fly a big commercial plane in the end.

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

#248

Post by salawat »

jussij wrote: post #119
golergka wrote: post #38

Earlier quoted context omitted.

> It was shameful to see Boeing actively encouraging that narrative behind the scenes. Is it shameful because we suspect that it was an intentional lie on their behalf, or is it shameful even if it was honest opinion of these Boeing representatives at the time?

> Is it shameful because we suspect that it was an intentional lie on their behalf Exactly this. > or is it shameful even if it was honest opinion of these Boeing representatives at the time? It seems fairly obvious Boeing was aware the 737-MAX had some serious faults, but instead of admitting those faults it seems fairly obvious they went out of their way to deflect blame way from their failed aircraft onto the now…

This is because of Product Liability law.

If they admit in any way to releasing a known dangerous product they open themselves to massive damages.

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

#249

Post by DuskStar »

sseth wrote: post #224
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…

Agreed. After the Lion Air crash, Boeing basically asserted the plane was perfectly safe, and that the pilots should have followed the runaway trim process - this means turning off the electric motor which moves the trim, and having the pilots move it manually using a wheel provided for the purpose. Boeing has tried to imply that in the midst of an emergency which looks very different from a runaway trim, pilots shou…

There's a major difference between the Lion Air and Ethiopian Airlines crashes though - altitude and incident duration. Things that are recoverable from 5000' AGL might not be from 1000' AGL. Speed is life, and altitude is life insurance after all.

From my reading, the Lion Air pilots could have disabled electronic trim anytime after those 26 recoveries and been fine. But the Ethiopian Airlines pilots only had 1000' of altitude to recover in, and that wasn't enough. Which leads to the question of why MCAS was triggering at 1000' AGL, since it isn't supposed to activate when flaps are deployed... I don't think MCAS is going to end up being the sole hardware issue on that flight.

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

#250

Post by simion314 »

7952 wrote: post #240
simion314 wrote: post #158

Earlier quoted context omitted.

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.

So you blame the pilot that he is not training itself in the new hidden changes of the airplane? Isn't Boeing duty to create the checklists/procedures for the possible issue ? or we let this work for the pilots internet forums?

Though from the article it appears that pilots followed all the official procedures,

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