Ethiopian Airlines plane crashes on way to Nairobi

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Re: Ethiopian Airlines plane crashes on way to Nairobi

Unread post by Wingnut » Thu May 16, 2019 11:58 am

There is a youtube video of a guy stopping the trim wheel by hand.
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Re: Ethiopian Airlines plane crashes on way to Nairobi

Unread post by heisan » Thu May 16, 2019 12:18 pm

love2fly wrote:
Thu May 16, 2019 10:37 am
Apologies if this suggestion has been raised as this thread gets bigger and bigger.
Also, I am not a pilot but an enthusiast of all things flying....

Would it not be a possible solution that the MCAS system be limited in how much input it can make, ie x no of degrees of stabilizer/trim, as it is my understanding that trim is there to fine tune and the pilot there to "fly"?
So the MCAS is given one attempt and thereafter it is up to pilot inputs and when happy they reset MCAS back to zero and continue?
In the same way that ABS/ESP etc can be full on, race or "off"?

Just a suggestion from a less informed individual.....

That is part of the software update. MCAS can only issue one trim event of up to 2.5 degrees without AoA first decreasing and then increasing again.
Wlotzkas wrote:
Thu May 16, 2019 11:38 am
I have a few questions:
1: On the runaway stabilizer checklist in the flight crew operations manual, it clearly state disengage AP, then auto throttle, then trim cutout switches. But why is there another "if" after trim cutout switches (grab and hold the trim wheel) in case runaway continues? There is not another "if" in case the AP or auto throttle do not disengage. Is that event handled in another checklist? Or might there be another way (other than a wiring problem or cutout switches failing) that will result in continued trim after the switches are at cutout that must be solved by holding the trim wheel? It seems a cutout switch failure is handled in the checklist, but not a failure of AP or auto throttle disconnect.
The checklist is to address a trim runaway only. Failure of the AP to disconnect would be a separate procedure.

There are many ways the trim could run away, and the procedure addresses each in turn. First disengage AP in case it is a spurious AP output. If that fails, turn off the cut-outs (which disconnects the FCC and trim switches from the trim motor). If that fails, grab the trim wheel, and mechanically stop the trim.
2: What happens if the pilot commands trim up and the MCAS commands trim down simultaneously? Which one have preference, or will the trim motor stop in that event? (two commands cancelling each other out?)
A manual trim event stops MCAS immediately and resets the MCAS system. MCAS will wait at least 5 seconds after the last manual trim event before re-enabling.
3: How much momentum is there in the trim wheel? Is it physically possible to "Grasp and hold" it to stop rotation from a fast spinning state without losing a finger or other injury? How practical is this solution?
Thanks!
No idea, but it does not look to hard in the video...
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Re: Ethiopian Airlines plane crashes on way to Nairobi

Unread post by PC » Fri May 17, 2019 8:53 pm

I would like to make a prediction: When the 'fix' has been made, and it has been scrutinised by all interested parties - and I believe it will be inspected like no other - then the B737 Max will be returned to service, and in time all will be forgiven.

Boeing has too much riding on this, and the airlines need this aircraft as well. I don't wish to debate whether Boeing screwed up - I think this is self-evident. It is, and will be, a damn fine aeroplane when this flaw is fixed.

Remember the A320 debut? Can we ever forget it doing that flypast and crashing into the forest? That was also a software flaw, if memory serves, and it went on to become Airbus top seller. They were lucky not to lose two, and both full of pax.

Airbus is busy finding out how much the failed A380 adventure cost. Boeing is busy finding out what this software blunder is going to cost.

Also, let us not forget B787's with burning batteries. Can we even remember that?

Personally I think its high time the airlines came up with a brand new medium size jet. The 737NG I fly now has very little to do with the 737-200 I started off on. Switches look the same, but behind the panels she's somewhat different.

I have flown an RV10 with better instrumentation that what is in the 737NG.

They should start designing the new ones with haste - this horse has run its course. The Max should give them 10 years to come up with something new. Probably not too different from the 777 and 787 to make conversions easier.
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Re: Ethiopian Airlines plane crashes on way to Nairobi

Unread post by jimdavis » Fri May 17, 2019 11:01 pm

PC, what you say make perfect sense. I suspect your prediction will prove correct.

The only thing that could throw a spanner in the works is if the new, improved, modded, certified MAX has an accident in the next couple of years, everyone is going to scream MCAS - even if it isn't!

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Re: Ethiopian Airlines plane crashes on way to Nairobi

Unread post by John.com » Sat May 18, 2019 2:28 pm

I don't mean to distract from the focus on issues surrounding the B737 Max, but I found this latest article on the QF72 A330 flight an extremely fascinating read, in particular with regard to the PTSD experienced by the PIC post such a fight in which the aircraft computer tries to wrestle control of the aircraft away from the pilot!

FYI: Oct 7th, 2008: QF72 was the Qantas flight from Singapore to Perth of an A330, which experienced a sudden inflight upset in what turned out to be the Airbus computer going rogue and forcing the aircraft into a nosedive, resulting from upsets triggered by spikes of up to +50.6 degrees in the AoA (Angle of Attack) sensor.

Take a read HERE: 'I’ve become very isolated': the aftermath of near-doomed QF72
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Re: Ethiopian Airlines plane crashes on way to Nairobi

Unread post by Mouser » Sat May 18, 2019 2:50 pm

From PC's post:

"Remember the A320 debut? Can we ever forget it doing that flypast and crashing into the forest? That was also a software flaw, if memory serves, and it went on to become Airbus top seller. They were lucky not to lose two, and both full of pax."

Interesting one - investigation ruled pilot error and I think he went to jail for a few years I think there were two or three deaths out of may 15 or 20 on the aircraft). He fought citing computer glitch, even alleging the black boxes were tampered with. Still fighting it maybe. All from memory so could be wrong.
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Re: Ethiopian Airlines plane crashes on way to Nairobi

Unread post by Romeo E.T. » Tue May 21, 2019 10:07 pm

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Re: Ethiopian Airlines plane crashes on way to Nairobi

Unread post by richard C » Wed May 22, 2019 8:23 am

Just digest the monthly finance charges in that little picture.
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Re: Ethiopian Airlines plane crashes on way to Nairobi

Unread post by Stephan van Tonder » Wed May 22, 2019 12:54 pm

Wonder if they pay for parking as well?.
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Re: Ethiopian Airlines plane crashes on way to Nairobi

Unread post by jimdavis » Wed May 22, 2019 3:07 pm

Stephan van Tonder wrote:
Wed May 22, 2019 12:54 pm
Wonder if they pay for parking as well?.
Why would they not? Poor muggers.

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Re: Ethiopian Airlines plane crashes on way to Nairobi

Unread post by Dragon » Wed May 22, 2019 5:16 pm

heisan wrote:
Thu May 16, 2019 12:18 pm


“3: How much momentum is there in the trim wheel? Is it physically possible to "Grasp and hold" it to stop rotation from a fast spinning state without losing a finger or other injury? How practical is this solution?
Thanks!”

No idea, but it does not look to hard in the video...
That trim wheel is a very solid rubbery plastic and it really spins fast. It is difficult to describe the sensation to someone who hasn’t done it, and there isn’t really an every day object to compare it to, but try this:

If you take your mountain bike and turn it upside down and grab the pedal and spin up the back wheel as fast as you can possibly go, and now with one movement grab the tyre in your hand and stop it in its tracks. It bites you like a cricket ball catch and leaves you nervous to grab it again. It hurts but it doesn’t injure you or cause damage. It can be done and it should be done when needed.
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Re: Ethiopian Airlines plane crashes on way to Nairobi

Unread post by jimdavis » Wed May 22, 2019 7:34 pm

Dragon wrote:
Wed May 22, 2019 5:16 pm
heisan wrote:
Thu May 16, 2019 12:18 pm


“3: How much momentum is there in the trim wheel? Is it physically possible to "Grasp and hold" it to stop rotation from a fast spinning state without losing a finger or other injury? How practical is this solution?
Thanks!”

No idea, but it does not look to hard in the video...
That trim wheel is a very solid rubbery plastic and it really spins fast. It is difficult to describe the sensation to someone who hasn’t done it, and there isn’t really an every day object to compare it to, but try this:

If you take your mountain bike and turn it upside down and grab the pedal and spin up the back wheel as fast as you can possibly go, and now with one movement grab the tyre in your hand and stop it in its tracks. It bites you like a cricket ball catch and leaves you nervous to grab it again. It hurts but it doesn’t injure you or cause damage. It can be done and it should be done when needed.
Isn't it more intelligent to stop it with your foot?

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Re: Ethiopian Airlines plane crashes on way to Nairobi

Unread post by MadMacs » Wed May 22, 2019 9:04 pm

jimdavis wrote:
Wed May 22, 2019 7:34 pm
Dragon wrote:
Wed May 22, 2019 5:16 pm
heisan wrote:
Thu May 16, 2019 12:18 pm


“3: How much momentum is there in the trim wheel? Is it physically possible to "Grasp and hold" it to stop rotation from a fast spinning state without losing a finger or other injury? How practical is this solution?
Thanks!”

No idea, but it does not look to hard in the video...
That trim wheel is a very solid rubbery plastic and it really spins fast. It is difficult to describe the sensation to someone who hasn’t done it, and there isn’t really an every day object to compare it to, but try this:

If you take your mountain bike and turn it upside down and grab the pedal and spin up the back wheel as fast as you can possibly go, and now with one movement grab the tyre in your hand and stop it in its tracks. It bites you like a cricket ball catch and leaves you nervous to grab it again. It hurts but it doesn’t injure you or cause damage. It can be done and it should be done when needed.
Isn't it more intelligent to stop it with your foot?

jim
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Re: Ethiopian Airlines plane crashes on way to Nairobi

Unread post by Wayne Boonzaier » Wed May 22, 2019 9:04 pm

After reading all of the posts on this thread there is only one solution that makes any sense to to fix an automation problem and that is Jims suggestion that there should be a "Cub Mode" switch that disengages all the automation and gives full control to the pilots of every primary and secondary flight control from throttles to rudder and stick and trim.

After the first uncommanded nose down push the pilots would have hit the "Cub Mode" switch and flown the aircraft manually the rest of the way and no one would have died.

When the computer becomes a psychotic killer switch it off and fly the aeroplane.
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Re: Ethiopian Airlines plane crashes on way to Nairobi

Unread post by MadMacs » Wed May 22, 2019 9:22 pm

Wayne Boonzaier wrote:
Wed May 22, 2019 9:04 pm
After reading all of the posts on this thread there is only one solution that makes any sense to to fix an automation problem and that is Jims suggestion that there should be a "Cub Mode" switch that disengages all the automation and gives full control to the pilots of every primary and secondary flight control from throttles to rudder and stick and trim.

When the computer becomes a psychotic killer switch it off and fly the aeroplane.
Or if Boeing had tied the system into the elevators rather than the stabilizer, which already has the speed trim control as well as the mach trim tied into it but then it would not allow grandfathering of the models.

I still think it was a software conflict between the speed trim and MCAS as well as the chaffing of the wiring to the AoA sensor, which can be seen as snags in the technical log prior to the crash - see interim crash report.
When they use the loaded term "denier" that should be the first clue that we're not dealing with a rational opponent in a debate... but "religious" dogma.

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