Ethiopian airliner down in Africa

[MemberBerry]

Originally Posted by Gilles Hudicourt

Correct me if I’m wrong, but in the case of the Lion Air accident, from what I understood, an AOA probe fault caused the MCAS to put a forward trim on the horizontal stabilisor, causing a fault that essentially looked like a runaway trim, a situation that a pilot could have recovered from by treating it like a runwaway trim.

If the above statement is correct, my question is this : did the MCAS also activate the stick shaker or any other kind of stall warning?

Because recovering from a down trimming runaway trim (pulling back on a very heavy control wheel) while at the same time having a stick shaker and some other indication telling you you are about to stall (which normally would require lowering the nose).....

The stick shaker was indeed activated on the Lion Air flight due to the incorrect AoA sensor readings, but the stick shaker has nothing to do with MCAS, its triggering mechanism is independent from MCAS.

In fact the stick shaker has also been active for almost the entirety of the previous flight, 90 minutes, for the same reason: incorrect AoA sensor readings.

And the pilots from the previous Lion Air flight seemed to fail to mention that the logs, for some unfathomable reason. Also not sure how they could stand having a stick shaker active for 90 minutes and not return to the departure airport. They might have pulled its circuit breaker to silence it.

The previous Lion Air crew also failed to mention in the logs they had to disable the automatic trim, after fighting with it for 5 minutes, to make the plane flyable.

Having done so would have helped the next Lion Air crew to diagnose the issue faster and apply the workaround before the plane become uncontrollable and crashed.

[PastTense]

The U.S. National Transportation Safety Board will send four people to assist in the fatal Ethiopian Airlines crash, an NTSB spokesman said on Sunday.The U.S. Federal Aviation Administration is also monitoring developments concerning the crash, a statement said. “We are in contact with the State Department and plan to join the NTSB in its assistance with Ethiopian civil aviation authorities to investigate the crash,” an FAA statement said.

https://af.reuters.com/article/topNe...BN1QR0JL-OZATP

Is four the usual size of the team? I would have expected a larger team.

[Daysleeper]

Originally Posted by PastTense

https://af.reuters.com/article/topNe...BN1QR0JL-OZATP

Is four the usual size of the team? I would have expected a larger team.

Four would be pretty normal, remember this is not a US investigation , it's an Ethiopian investigation which the NTSB is a participant in. Their main role is being the conduit between the Ethiopians and Boeing / CFM / FAA / suppliers and also providing specific requested technical expertise.

[lomapaseo]

There seems to be in this thread an early fixation on a previously known cause. This flies in the face of the ability of the industry to assimilate previous causes and promulgate corrective actions world wide.

I'm not about to give much credence to anybody suggesting a cause unless equal arguments include previously identified corrective actions being missing

[gums]

Salute!

@Gilles

Correct me if I’m wrong, but in the case of the Lion Air accident, from what I understood, an AOA probe fault caused the MCAS to put a forward trim on the horizontal stabilisor, causing a fault that essentially looked like a runaway trim, a situation that a pilot could have recovered from by treating it like a runwaway trim.

I am willing to bet that most of us think of "runaway trim" as a fairly constant uncommanded trim that we didn't expect. The MCAS trim implementation is maybe ten seconds of nose down unless you use the manual trim switch or wheel, then it "rests" for 5 seconds and tries to kill you again!!! So sympton is like "intermittent trim" or basically FUBAR trim, especially if not briefed on the MCAS implementation and realizing that the stick shaker and stall alarm was telling me to push over, but Hal was overdoing it.
The previous Lion Air crew turned off the trim and until we hear their testimpny, they may not have realized that their own plane had MCAS failure. And looking at their FDR plots, it was classic MCAS. just like flight 610 the next day.

@CONSO The flap retraction altitude/procedure for the 737MAX is not in my memory bank Seems that normal retraction requires a trim change in most planes ( Airbus, Viper, Raptor, maybe 777 excepted), but not flying that type I am not sure. In any case, it's a configuration change and that is not a great time to have uncommanded trim you are not expecting or trained for.

For the "shut up and wait" folks!! This is a "rumor" forum, but if I were flying this type I would sure as hell be reviewing everything I could get my hands on about the systems' operation ofter gear up and establishing a stabilized climb, and talking with other pilots flying the beast.

Gums opines....

[Rananim]

There seems to be in this thread an early fixation on a previously known cause. This flies in the face of the ability of the industry to assimilate previous causes and promulgate corrective actions world wide.

You would think so but it seems not.
The Flight Radar data fits another MCAS event and not much else.
737s dont just augur in.
Flap retraction can be initiated as low as 400 feet,more commonly 800 feet.
So MCAS event is entirely feasible.
Skipper new to type<-------red flag
Co-pilot 200 hrs<-------red flag
New Skipper rostered with inexperienced co-pilot<------huge red flag
Ethiopian track record<------red flag

[PastTense]

Originally Posted by lomapaseo

There seems to be in this thread an early fixation on a previously known cause. This flies in the face of the ability of the industry to assimilate previous causes and promulgate corrective actions world wide.

I'm not about to give much credence to anybody suggesting a cause unless equal arguments include previously identified corrective actions being missing

See thread:
Boeing 737 Max Software Fixes Due to Lion Air Crash Delayed
Thus Boeing hasn't implemented any fixes of the MCAS problem yet. While many airlines probably did some additional pilot instruction and other pilots learned of the problem in places like PPRUNE, many other pilots probably didn't.

And of course even if a pilot was informed of something doesn't mean he will remember it in a critical situation.

[Lonewolf_50]

Originally Posted by Rananim

The Flight Radar data fits another MCAS event and not much else.

I will comment on your "not much else" line.
(1) This was mentioned some pages back, but ... given the altitude, "high hot heavy," and location, another possibility is a bunch of birds being eaten by two engines.
Crew is playing catch up the whole way down, high task saturation, very little altitude to work with. (And I think it's rising terrain? Not familiar with the area).
That's a guess, since there's not a lot of supporting information. The FDR would be able to identify that kind of thing early in the analysis.
(2) Here's another one that is far less likely, but that also fits: bad fuel. (Didn't they just fill up after unloading from the previous flight?)
Lose one, lose two, and now you have to do your best-ever engine out drill at high gross weight and (I think?) rising terrain. (If that part is wrong, rising terrain, map study failure on my part).
Why I think it wasn't that second one.
The reported radio call about "return to field" ... but that could be for a variety of things going wrong.
More detail hopefully soon.

I don't make this post to belittle your analysis, because I think that in the main you are thinking the problem through.

I am jumping on the band wagon with lomapaseo: we might be dealing in a little bit of confirmation bias in the early reaction to this tragic loss of life.

[Smythe]

What I am pointing out is jumping on the wagon with what lomapaseo was getting at: we might be dealing in a little bit of confirmation bias in the early reaction to this tragic loss of life.

yes, that is certainly true. now, on the flip side, considering how many hours the MAX has vs hull loss.4 months to a hull loss. times 2

there is a problem.

[marie paire]

And... B737 Max 8, RED flag,,,

[gums]

Salute!
This might be a workable URL from Past Tense post above.Original may have been corrupted.
The certification issue is mentioned, as well as informing crews and such.

Boeing 737 Max Software Fixes Due to Lion Air Crash Delayed

Gums sends...

[scr1]

a report of possible engine problems

https://www.timesofisrael.com/israel...medium=twitter

[silverstrata]

Originally Posted by MemberBerry

Not sure exactly about which controls are you talking about, and what exactly do you mean, but as far as I know at the very least the elevator controls can be split on the 737.
There is a breakout connection between the two control columns that can disconnect if the torque applied on it becomes too high, for example if the elevator on one side of the aircraft is stuck.

Not true, there is a ruddy great toque tube that connects both elevators on the 737. You can (supposedly) disconnect the control columns, but you cannot separate the elevators. So if one jams, the other is too. Oh, and BTW, have you ever come across anyone who has done a control colum disconnect in the sim? Ever?

Face facts, the 737 would not pass certification today. Its rests its entire certification upon its 1967 grandfather rights.

Silver

[Running Ridges]

Originally Posted by scr1

a report of possible engine problems

Does that not sound more like an APU issue than an engine issue?
Lack of Air Conditioning before start + unusual start procedure

Before takeoff, “the passengers understood there was a problem. It was hot, they didn’t give out water,” he said.

Israeli Ambassador to South Sudan Hanan Godar (screen capture: Channel 13)The pilot informed them of a problem with one of engines, telling them: “We’ll operate one engine to see if it catches, and if it catches, we’ll start the other engines,” Godar said.

[Photonic]

Originally Posted by NWA SLF

A CEO at a crash site is an important sign of a company commitment.

A CEO standing outside the roped-off area at a press conference is how that's normally done, as a sign of company commitment. A CEO standing in the middle of the wreckage and handling crash parts, is just setting a terrible example for others to follow.

[Lonewolf_50]

Originally Posted by scr1

a report of possible engine problems

https://www.timesofisrael.com/israeli-says-he-was-on-ethiopian-jet-days-before-it-crashed-it-had-engine-woes/?utm_source=dlvr.it&utm_medium=twitter

Also a possible passenger who knows not very much about aircraft and engines. That "report" is rather low on the credibility list, given that the gent was on the aircraft on Thursday. We'll see what the FDR has (hopefully) in due course.

[Lonewolf_50]

Originally Posted by Smythe

yes, that is certainly true. now, on the flip side, considering how many hours the MAX has vs hull loss.4 months to a hull loss. times 2

there is a problem.

Or there may be two different problems. We'll see.

[Raffles S.A.]

While those who are arguing about the CEO holding a piece of wreckage, have you seen the vidoes of 100s of locals walking over the crash site?

A message recieved from a pilot friend who was at the holding point when the doomed aircraft took off, he says that the takeoff seemed normal but shortly after the aircraft declared an emergency stating unreliable airspeed and difficulty controlling the aircraft.

[silverstrata]

Originally Posted by lomapaseo

There seems to be in this thread an early fixation on a previously known cause. This flies in the face of the ability of the industry to assimilate previous causes and promulgate corrective actions world wide.

What do you expect? MCAS is a cheap (and semi-back-door) stick pusher system. It is far from ideal, but was a simple software change rather than a complete new stick-push system, which is what should have been fitted. Face facts, MCAS was a hurried and ill-thought-out fix, to yet another upgrade to a 60-year old airframe - and it is known to have already caused one tragic loss, iin very similar circumstances to the oresent incident. You think it is not justified to bring up the MCAS system again - because I have not heard that the system has been changed in any way. It is still sitting there, like a brooding gremlin, ready to pluck aircraft out of the sky at any minute.

And Boeing have still not explained the logic of of a pseudo-stick-push that keeps operating again and again and again, until you get full forward trim. Have you tried this MCAS-trim-runaway in the sim? According to the sim, the aircraft is only just about controllable with two gorillas hauling back in unison, with both feet up on the foot-bar and hauling about 40 kg pressure on each stick. And that was in level flight with the CofG in the central position. Ok, now try a recovery from a stall-dive, with a forward CofG, with 20º nose down pitch, and with the speed rapidly increasing to 250 kt. It is absolutely impossible - you are doomed. And doomed by an anti-stall system that is supposed to save you. But who in the world would want to recover from a stall, with the trim-stabiliser set fully forward? Who thought that ine up? The stabiliser is more powerful than the elevator, and will take you straight down to terra-firma. Heck, even the Wright Brothers knew not to design something like that.

Silver

[b1lanc]

Originally Posted by Lonewolf_50

I don't mean to be a wiseass, but the graph shows that it was climbing when it hit. (Or am I reading the graph incorrectly?) Is someone using non standard notation there?

I don't think you are being a wiseass - take it for what it's worth - posted on Daily Mail. Like I said, they didn't site a source. Do we really know how long it was airborne? Also doesn't seem to mirror the earlier plot posted. Compares to #56 permalink.