For the aviation fans

[MrJacques]

https://www.businessinsider.co.za/ethiopian-airlines-boeing-737-max-crash-575mph-32ft-crater-2019-4-2

[Long Wheel Base]

[Long Wheel Base]

[Bateleur1]

This will be a easter hunt of note ...

 

https://www.businessinsider.co.za/japan-lost-an-f-35-in-the-pacific-russia-or-china-may-find-it-first-2019-4

 

Reminds me of the time when the F-14 Tomcat with its AIM-54 Phoenix missiles were the next best thing and one of them with a full load of Aim-54 went overboard in international waters.  The Ruskies could not get there fast enough to try and get their hands on the tech.  The US managed to find the plane an quickly enough then.

[DJR]

I'm in 2 minds about how appropriate humour is re. this tragedy, but then, one should be able to laugh at it, not so? 

[Capricorn]

This will be a easter hunt of note ...

 

https://www.businessinsider.co.za/japan-lost-an-f-35-in-the-pacific-russia-or-china-may-find-it-first-2019-4

 

Reminds me of the time when the F-14 Tomcat with its AIM-54 Phoenix missiles were the next best thing and one of them with a full load of Aim-54 went overboard in international waters.  The Ruskies could not get there fast enough to try and get their hands on the tech.  The US managed to find the plane an quickly enough then.

stealth jet goes missing? defection?

[Headshot]

On the 737 Max disaters - The basic 737 airframe is an old design. This led to regulatory laxity as because of its legacy, it seems certification of the new versions was less stringent than a brand new airframe.  Had Boeing redesigned the plane as they should have once they started hanging much bigger engines under the wings, the MCAS system would not have been needed in its current form or perhaps at all. The old airframe was good but the engine changes  made it poor in certain performance areas. One of the root cause of the crashes  is Boeing's attempts to remain competitive and maximize profits by reusing an old airframe and even then keeping the MCAS system effectively a secret to avoid retraining costs for airlines. This is the very ugly side of big business. Expect a movie or two about this...

 

Will a software fix alone actaully make the plane safe bearing in mind that to do it properly may require airframe changes like adding a second or third AOA sensor? What scares me is how the  poor design and implementation of the system by Boeing was permitted by the FAA which outsourced its core function to Boeing itself. Thats a massive conflict of interest issue that I am sure lawyers for victims will seize on.

 

What Boeing will  do in any legal action it faces is argue that a competent crew following standard procedures could have saved both planes. They will point to how other pilots in other planes were able to manage similar situations and survive. 

 

It will be interesting to see the final reports rate the crew performance.  Politics and public relations are already playing out in this area.The Ethiopians have claimed that the pilots did everything right which is clealry not the case. They kept the plane at full throttle which  contrubuted to the loss of control.

 

Very interesting but scary and tragic too. 

[Long Wheel Base]

This will be a easter hunt of note ...

 

https://www.businessinsider.co.za/japan-lost-an-f-35-in-the-pacific-russia-or-china-may-find-it-first-2019-4

 

Reminds me of the time when the F-14 Tomcat with its AIM-54 Phoenix missiles were the next best thing and one of them with a full load of Aim-54 went overboard in international waters.  The Ruskies could not get there fast enough to try and get their hands on the tech.  The US managed to find the plane an quickly enough then.

What I find interesting(or scary) is that in today's day and age, we still have nations that are prepared to go to war right now. I can understand having military for terrorism but when they openly say they want that technology to clone it is scary to me. 

[Robbie Stewart]

The preliminary report on the recent 737 Max disaster is here if you haven't seen it:

 

http://www.ecaa.gov.et/documents/20435/0/Preliminary+Report+B737-800MAX+%2C(ET-AVJ).pdf

 

 

My summary:

Left AOL or feeder circuit fails shortly after take off

MCAS tries to trim down

Pilots try to trim up

Speed keeps on increasing

Trim Motor Cut Out switches enabled as per the procedure (which also calls for them to remain off for the duration of the flight)

MCAS tries to trim down but does not result in change of horiz stabliser angle, consistent with the trim motors being switched off

FO tries manual trim wheels but can't turn them (presumably because of the high speed causing high forces on the mechanism). Not indicated whether both tried

Electric Trim is used again to try trim up (were the CO switches reversed?)

MCAS then trims down because the motors were on and pitches the aircraft nose down 40deg and 500 knots into the ground.

 

One possible explanation is that the electric trim switches were moved back up because they could not manually trim up. Apparently there are techniques for dealing with this in this state.

 

Question I have is why the speed continued to increase to Vne (never exceed) "the N1 Reference remained about 94% and the throttles did not move." Does that means the throttle levers were left full taps?

 

In my PPL training, although a distant past, I remember one thing, the first thing from dealing with an emergency "FLY the airplane"

 

The tragic flaw in this airplane is the MCAS relying on only one AOA sensor. And the "AOA Disagree Indicator" being an option. Here is where Boeing is going to have a problem.

 

Training videos I have seen is that the manual trim wheels need some muscle power to crank, Resistance will go up with the square of the speed.

 

I recall reading that apparently the throttles were indeed left at full-tap, and the question was raised why neither pilot throttled back, according to the DFDR. 

 

Because of this, the forces acting on the elevators were to strong to be overridden by manual trim rotation, and instead of throttling back to reduce speed and the resultant forces being applied, the AP was switched back on again, leading to MCAS instantaneously responding with a nose pitch-down.

[Capricorn]

stealth jet goes missing? defection?

nevermind, we still on a path to some global war: the wreckage was found, pilot still missing.

[kosmonooit]

I recall reading that apparently the throttles were indeed left at full-tap, and the question was raised why neither pilot throttled back, according to the DFDR. 

 

Because of this, the forces acting on the elevators were to strong to be overridden by manual trim rotation, and instead of throttling back to reduce speed and the resultant forces being applied, the AP was switched back on again, leading to MCAS instantaneously responding with a nose pitch-down.

 

 

It is in that preliminary report it states that the throttles were effective left (untouched) full forward, so that is a primary source of that info.

 

It seems one of the crucial factors here (not saying errors because there could have been some circumstances) One of the rules of flying that linger in my memory from my flying days is Height with Power, Speed with Stick, so why did the aircraft not climb with the increased speed? because it was being trimmed nose down continually as I see it.  So it just went faster and faster.... causing the massive pressure of that jack/lead screw that could not be over come by the FO using the trim wheel.

 

Its not clear if the pilot tried to assist in the manual trimming. In one of Mentor Pilots youtube videos he deals with a horiz stab trim runaway procedure, the FO was on the whimpish side and the pilot had to help crank with the fold out handles. I wonder if that high speed simulated would also give associated high resistance on that control.

 

Media reports are that the pilots followed all procedures as claimed by that Ethiopian official in that press conference but  switching back on the electric trim goes against the proc (quoted in that report) that says the trim cutout switches must be left off for the remainder of the flight and that seems to have been the final straw because that meant the MCAS gave another session of fatal nose down trim... and besides that, not controlling the speed,

 

I guess the Voice recorder will reveal the situation more.

Edited April 11, 2019 by kosmonooit

[Ed-Zulu]

But...some of the pilots interviewed after reading the report stated that in that situation they would probably have handled it the same and that the flight crew did very little wrong in the situation.

 

Meaning that when some things go wrong, some other things become secondary to the problem trying to be solved.

 

What is very clear is that the system is flawed and peoples lives are at risk with the current configurations.

[SwissVan]

Playing catch up here due to limited time, 2 burning questions:

 

Q1: did the crew turn off the 2 stab trim cut out switches on the Center pedestal??

Q2: did the crew attempt to manually retrim nose up?

This would take a lot of manual trim wheel turning and should be obvious on cvr recording

 

Without performing these 2 actions the crew and aircraft did not have a hope

[eddy]

I recall reading that apparently the throttles were indeed left at full-tap, and the question was raised why neither pilot throttled back, according to the DFDR. 

 

 

Because closing a throttle in the aircraft has the effect of dropping the nose and they were already  fighting a nose down attitude. 

[Bateleur1]

Because closing a throttle in the aircraft has the effect of dropping the nose and they were already  fighting a nose down attitude. 

 

I am just thumbsucking here but is it possible that there were no stall warning, hence not throtteling back that would have been a normal procedure.  I understand in a stall, before giving more power to gain speed you first need to get the nose down then throttle up.  But if there were no stall warning and the nose pitches down, it could cause major confusion to the problem and the first thing in an emergency is fly the plane.

[SwissVan]

I am just thumbsucking here but is it possible that there were no stall warning, hence not throtteling back that would have been a normal procedure. I understand in a stall, before giving more power to gain speed you first need to get the nose down then throttle up. But if there were no stall warning and the nose pitches down, it could cause major confusion to the problem and the first thing in an emergency is fly the plane.

The plane was reportedly porpoising with a final decent angle of 40 degrees and speed of + 900kmh

In broad daylight. Sounds like to me they were trying to fly the plane but not doing the right things.

 

Easy to say from my armchair