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marcelh
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 06, 2019 1:18 pm

MD80Ttail wrote:
marcelh wrote:
MD80Ttail wrote:
The FO didn’t know what he was doing either. Maybe he thought he knew what he was doing.....not his fault. But having a FO with 150-200hrs TOTAL time is literally criminal. At 200hrs TT the plane is flying you....you are not flying the plane.....you are behind the aircraft w 200hrs TT.

I repeat my statement: if lack of training/hours is so criminal, why don’t we read that a NG or A320 has made a crater?



Too many to list.

Too easy....

I don’t want to misjudge your opinion about 200 hours and if it’s enough or not to become a FO. Fact is that it happens and the 737NG or A320 are very safe planes to fly. Otherwise we should have a crater once a week with 100-180 victims. Boeing sells the 737 MAX as “just another 737”, but when the shit hits the fan, it isn’t just another 737.
 
mandala499
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 06, 2019 1:21 pm

speedbored wrote:
I still do not believe it, because it is not true. At no point was the aircraft ever below FL050, not even while still on the runway.

Take note of the phase of flight that the pilots were in (climb - they were trying to get to 14,000ft), and the altitude they were actually at, and look at the pitch and power settings again.

Regardless of the tables, it is clear from the CVR recordings of overspeed warnings, that the pilots maintained an airspeed within the limits of the airframe for at least the first half of the flight, until they really started to struggle with, and get distracted by, controlling the aircraft. Even then, the overspeed was minor and intermittent according to one side of the aircraft, When presented with multiple different issues, and expending considerable effort on trying to keep the nose up (the overspeed warnings don't kick in until ~80 seconds after both pilots start pulling hard back on the yokes), the pilots have to prioritise what they work on.

Yeah, well, the idea of reducing N1 to 75% is... well... you know...

For the benefit perhaps Morrisond...
Climb at flaps up at unreliable airspeed, as we know, is at max climb thrust (N1 way over 75%), with pitch at 9.5 or more degrees, for a 737-800... The max would have similar numbers...

75% N1 is for cruise with unreliable airspeed at 15000ft... pitch 3.5, N1 75%... and that is for LEVEL flight...

The overspeed warnings, probably came from not reducing the thrust once they wanted to go level... but then, given what they were faced with, am not surprised they didn't end up doing a pitch and power for level flight, because they were task saturated in getting control of the aircraft.

For the Lion Air, both 043 and 610 they didn't overspeed... the question is, why did ET302 have overspeed? Not saying who/what's wrong, but important to understand what went on in the mind of the pilot and what he was trying to prioritize at the time.

asdf wrote:
DIRECTIVE:

in emergency use the hand break to reduce speed of the car

NOTE:

we recommend you to stop the car before you apply hand break

Spot on!

MD80Ttail wrote:
That’s not what I said.....when flaps were retracted the problems started. I would have redeployed the flaps immediately while still at a safe speed. I have been reading here 10 plus years and finally made an account...but the whole forum has become like the news. Pick one word and focus on it to try and make a point. I never suggested deploying the flaps at an unsafe speed. My point was I would have wanted electric trim and no MCAS. Understanding the system after the Lion crash I would have immediately redeployed flaps which should give me what I want.

I agree with this. The crew of 610 did redeploy flaps when MCAS initially played up... but they retracted it again. The mindset flow goes with your saying of "if you do somthing in a plane and it immediately doesn’t like what you did go to back to prior config"... And before anyone has a go at you for this, let me also say, that, this is not monday morning quarterbacking like some would like to accuse you of.

SheikhDjibouti wrote:
This is probably my fault for not spelling out my main point clearly enough.
The "something else" was autopilot randomly disengaging.
If flaps retraction had been the only action in this 15 second window, MCAS would not have activated at 05:40:00

The autopilot disengaging is likely to be due to the MCAS wanting to engage. After all, if you set your autopilot to a selection where you would cause a stall, you'd want it to disengage... not sure of the detailed logic of the 737 Autopilot in the realms of near stall, plus the addition of MCAS on the Max on top... but just by common sense, you'd want the MCAS to disengage the A/P and then command trim nose down if you're in an actual stall... especially if the A/T isn't disengaged.

SheikhDjibouti wrote:
Captain Hindsight with a possible answer here;

1. Re-engage stab trim cut-out
2. Immediately (or even sooner than that!) use thumb switches, and continue to depress the thumb switch to prevent MCAS function.(*)
3. Now, in conjunction with the electric motor attempting to move the stabiliser, both pilots crank the manual trim wheel
4. You now have one electric motor plus two pilots attempting to move the jackscrew
5. If that fails; pray.

You mean 1 = provide power back to the stab trim? :)
I really wonder what Boeing was thinking, having the yoke in the aft (nose up) position and trying to manually crank the trim wheel (especially with heavier than normal forces), isn't an easy walk in the park for some.
What the crew of 302 tried to do was probably what you said above, except for #3, because I think just use the thumb switch for the electric trim should be enough but they needed to do it immediately after reengaging power to the stab trim.
I think the investigation will go deeper into this...

MD80Ttail wrote:
Two. Why didn’t the pilots up trim inputs time out MCAS allowing for the electric trim to be shut off after the pilots had commanded an acceptable trim condition? When conditions changed and the pilots needed more trim ok from what I’ve read and learned the manual trim wheel maybe was useless. That’s a Huge concern. No plane should ever be designed that can’t be manually trimmed.

I think the AD was badly worded that caused pilots reading it, to think, "OK I'll cut it off immediately"... and then lower down, it says, "you may use electric trim to reduce the load forces" (or something like that)... BUT HECK! YOU TOLD ME TO CUT IT OFF !!!!

The lack of emphasis to retrim the aircraft prior to cutting out the stab trim within the AD's wording and content structure, is my guess as being the culprit.

Oh hang on, is someone going to accuse me of being on Boeing's or FAA's payroll for saying that?
When losing situational awareness, pray Cumulus Granitus isn't nearby !
 
morrisond
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobiq

Sat Apr 06, 2019 1:21 pm

speedbored wrote:
morrisond wrote:
I was just replying to speedbored that He didn't believe setting N1 to 75% was the published procedure

I still do not believe it, because it is not true. At no point was the aircraft ever below FL050, not even while still on the runway.

Take note of the phase of flight that the pilots were in (climb - they were trying to get to 14,000ft), and the altitude they were actually at, and look at the pitch and power settings again.

Regardless of the tables, it is clear from the CVR recordings of overspeed warnings, that the pilots maintained an airspeed within the limits of the airframe for at least the first half of the flight, until they really started to struggle with, and get distracted by, controlling the aircraft. Even then, the overspeed was minor and intermittent according to one side of the aircraft, When presented with multiple different issues, and expending considerable effort on trying to keep the nose up (the overspeed warnings don't kick in until ~80 seconds after both pilots start pulling hard back on the yokes), the pilots have to prioritise what they work on.


You do understand the normal speed for the 737 is 230 Knots indicated? Close to Vmo would be way out of the normal operating range but still within the flight envelope - Vmo would be the speed you would not really want to above or get near too while descending.
 
mandala499
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 06, 2019 1:26 pm

[photoid][/photoid]
morrisond wrote:
You do understand the normal speed for the 737 is 230 Knots indicated? Close to Vmo would be way out of the normal operating range but still within the flight envelope - Vmo would be the speed you would not really want to above or get near too while descending.

You do realize/understand the normal climb / descent speed for a 737 above 10,000ft is 280kts or 0.76M (for NG and Max, 0.72 or 0.74 for the Classics) whichever is lower? (indicated airspeed)
Last edited by mandala499 on Sat Apr 06, 2019 1:26 pm, edited 1 time in total.
When losing situational awareness, pray Cumulus Granitus isn't nearby !
 
morrisond
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 06, 2019 1:26 pm

SomebodyInTLS wrote:
VV wrote:
If you switch them OFF it is then to fly the aircraft manually. And manual means the manual trim wheel (and the handle) without the help of any electrical power. That's my interpretation anyway.

So I am totally confused by the report.


I can't understand why when it's been pointed out dozens of times already.

1) they followed all of the memory items according to the AD issued after the Lion Air crash, however they had not fully corrected the MCAS trim with electric trim during this process (referred to as manual electric trim in the preliminary report)

2) at the end of this (trim switches cut off) they were physically trying to apply more manual trim using the wheels but were unable to presumably due to aerodynamic forces from the high speed (blowback)

3) they switched electric trim back on to try and correct the trim with "manual electric" again, but their trim corrections were less than those in the opposite direction by the re-connected MCAS

So the issue is why their manual electric trim was repeatedly less than sufficient - it now seems possible that the electric trim was also having issues with blowback.

Then the question is why they didn't reduce airspeed - well they didn't have pitch control and couldn't simply reduce thrust since they were very close to the ground


From the printed conversation it appears they only tried manual trim for 8 seconds and it was probably only one of them.

They were 8,000’ AGL - which while low is still sufficient altitude to try a few things - they were not 1,000’ AGL as speculated and repeated to me before this thread was started.
 
SimonL
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 06, 2019 1:36 pm

The initial GPWS warnings is probably a reason to why they didnt reduced power.
 
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speedbored
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobiq

Sat Apr 06, 2019 1:36 pm

morrisond wrote:
speedbored wrote:
morrisond wrote:
I was just replying to speedbored that He didn't believe setting N1 to 75% was the published procedure

I still do not believe it, because it is not true. At no point was the aircraft ever below FL050, not even while still on the runway.

Take note of the phase of flight that the pilots were in (climb - they were trying to get to 14,000ft), and the altitude they were actually at, and look at the pitch and power settings again.

Regardless of the tables, it is clear from the CVR recordings of overspeed warnings, that the pilots maintained an airspeed within the limits of the airframe for at least the first half of the flight, until they really started to struggle with, and get distracted by, controlling the aircraft. Even then, the overspeed was minor and intermittent according to one side of the aircraft, When presented with multiple different issues, and expending considerable effort on trying to keep the nose up (the overspeed warnings don't kick in until ~80 seconds after both pilots start pulling hard back on the yokes), the pilots have to prioritise what they work on.


You do understand the normal speed for the 737 is 230 Knots indicated? Close to Vmo would be way out of the normal operating range but still within the flight envelope - Vmo would be the speed you would not really want to above or get near too while descending.

Yes, I am well aware of what is "normal", thanks. I'm also well aware of what Vmo is. My point is that you were wrong to assert that the pilots should have set thrust to 75% N1. What exactly is your point?
 
MD80Ttail
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 06, 2019 1:42 pm

Since this thread is all over the place....I can’t find the quote... it’s back a ways.....but someone made a comment about the pilot not understanding his plane in 587. It was Airbus and to some extent AA that didn’t understand the plane. The FO...PF...I think his name was Stan Mollen (so) understood very well exactly what he was taught and practiced and further executed what he was taught and practiced. The plane was below Va. Until this accident every pilot in the world was taught at or below Va you have full use of all control surfaces to their maximum extent and structurally the aircraft will safely handle maximum deflection of all control surfaces.

Airbus...oh wait didn’t even think about this...HID the engineering and design facts, flaws, from the airlines and pilots.....the vertical stab wasn’t strong enough to withstand full deflection of control surfaces at or below Va.

We can argue he shouldn’t have been doing river dance with the pedals. His actions do seem overly aggressive to me. However, up until that point in avaiation history Va meant do whatever you needed or wanted with control inputs without worry of anything bad happening.

I remember....stupidly now...pounding the pedals to watch the tail wag on the Piper Tomahawk. It was stupid I agree but I was much much younger and inexperienced then but I had no worry about tail breaking off because I trusted the manufacturer and trusted what Va meant. Great fun to have your pax watch the tail wag. Again I was young and stupid. Probably had 100-200hrs TT then. Oh wait. Today I could be flying mainline with those hours. :)
 
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AirlineCritic
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 06, 2019 1:43 pm

MD80Ttail wrote:
MCAS was “working properly”—by that it was doing what it was designed to do.


To be honest, this may (but only may -- see below) be true. But it feels like a planted distraction. Of course there are many aspects of this accident, some things worked some things did not, and in the end the cheese holes sadly lined up. But why emphasise that the MCAS worked as designed? Why don't you start listing that it was badly designed, badly informed about, procedures for it were possibly badly designed, and it was possibly imperfectly maintained and used (but maybe understandable, given lack of info and bad processes).

Furthermore, I do not believe it has been proved even that MCAS worked as designed. I haven't looked at the latest FDR logs, maybe there's some new information. But I've assumed from the start that one possible reason for the failures is that something else than the sensor failed, e.g., the MCAS software or some computer component. That would have explained, for instance, how the problems continued even after the Lion Air maintenance reportedly fixed or replaced sensors from previous flight. Of course there's other possible reasons for the maintenance problems, but this just goes to show that there can be other issues than design issues.
 
MD80Ttail
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 06, 2019 1:44 pm

AA was teaching and promoting very aggressive use of rudders for escape maneuvers on all types up until 587.
 
SimonL
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 06, 2019 1:49 pm

We should also be able to end the debate of "why didnt they lower the flaps?" The FDR data shows that by the time they realized that it was an MCAS issue they where already too fast..
 
dragon6172
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 06, 2019 2:01 pm

mandala499 wrote:
SheikhDjibouti wrote:
This is probably my fault for not spelling out my main point clearly enough.
The "something else" was autopilot randomly disengaging.
If flaps retraction had been the only action in this 15 second window, MCAS would not have activated at 05:40:00


The autopilot disengaging is likely to be due to the MCAS wanting to engage. After all, if you set your autopilot to a selection where you would cause a stall, you'd want it to disengage... not sure of the detailed logic of the 737 Autopilot in the realms of near stall, plus the addition of MCAS on the Max on top... but just by common sense, you'd want the MCAS to disengage the A/P and then command trim nose down if you're in an actual stall... especially if the A/T isn't disengaged.

I think the AP disengaging would be from the bad airspeed and altitude data. Autopilot does compare notes with the other FCC, MCAS does not. The reason MCAS isn't needed when the autopilot is engaged is because it is just a function of what the AP does to stay away from that part of the envelope that MCAS is needed.
Phrogs Phorever
 
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speedbored
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 06, 2019 2:01 pm

morrisond wrote:
They were 8,000’ AGL - which while low is still sufficient altitude to try a few things - they were not 1,000’ AGL as speculated and repeated to me before this thread was started.

No, they were not. They never even got more than ~6,500ft above the airport elevation. The data is there in the interim report; you don't have to make it up.

At the point when MCAS kicked in, the aircraft was at roughly 1,000ft AGL
 
dragon6172
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 06, 2019 2:16 pm

speedbored wrote:
SheikhDjibouti wrote:
If for some reason the pilots maintained pressure on the thumb switch and yet MCAS still activated, then maybe this is the hidden problem Boeing are now trying to solve. :scratchchin:

I suspect that the additional problem Boeing are investigating will be related to the lack of response from the trim system to the pilots electric trim command at 5:40:15, when the aircraft was still considerably below Vmo. Compare the pitch trim response to the response seen to a slightly shorter trim commands at ~5:39:20, or ~5:38:50. Why was the response at 5:40:15 almost non-existant?

Flaps. The main electric trim moves slower when flaps are retracted. With flaps retracted the thumb switches move trim at about the same speed as autopilot trim (MCAS). With flaps extended the thumb switches move trim faster. At 5:39:20 and 5:38:50 the flaps are extended. At 5:40:15 flaps are retracted.

So the trim movement at 5:40:15 seems less because it moves slower and they let go of the trim switch. The question is why are the pilot commanded nose up trim inputs so short, before trim is cutout, and then after it is turned back on.
Phrogs Phorever
 
XRAYretired
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 06, 2019 2:49 pm

dragon6172 wrote:
mandala499 wrote:
SheikhDjibouti wrote:
This is probably my fault for not spelling out my main point clearly enough.
The "something else" was autopilot randomly disengaging.
If flaps retraction had been the only action in this 15 second window, MCAS would not have activated at 05:40:00


The autopilot disengaging is likely to be due to the MCAS wanting to engage. After all, if you set your autopilot to a selection where you would cause a stall, you'd want it to disengage... not sure of the detailed logic of the 737 Autopilot in the realms of near stall, plus the addition of MCAS on the Max on top... but just by common sense, you'd want the MCAS to disengage the A/P and then command trim nose down if you're in an actual stall... especially if the A/T isn't disengaged.

I think the AP disengaging would be from the bad airspeed and altitude data. Autopilot does compare notes with the other FCC, MCAS does not. The reason MCAS isn't needed when the autopilot is engaged is because it is just a function of what the AP does to stay away from that part of the envelope that MCAS is needed.

Yes. AP OFF is a pre-requisite for MCAS active as covered many, many times in these threads. Watch out for continual miss-direction and deflections by the 'gamers' on this thread (I'm not referring to anyone in the string above, they know who they are). They might go away if posters stop replying to the baiting. Well we can hope.


Ray
 
mwmav8r01
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 06, 2019 3:15 pm

marcelh wrote:
MD80Ttail wrote:
marcelh wrote:
I repeat my statement: if lack of training/hours is so criminal, why don’t we read that a NG or A320 has made a crater?



Too many to list.

Too easy....

I don’t want to misjudge your opinion about 200 hours and if it’s enough or not to become a FO. Fact is that it happens and the 737NG or A320 are very safe planes to fly. Otherwise we should have a crater once a week with 100-180 victims. Boeing sells the 737 MAX as “just another 737”, but when the shit hits the fan, it isn’t just another 737.



Thats not how these things work. It takes a series of errors USUALLY to cause an accident. Any break in the chain will save the day. Experience helps, but it isnt everything. Training helps but it isnt everything. Regulation helps but its not everything.
 
hivue
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 06, 2019 3:18 pm

SomebodyInTLS wrote:
2) at the end of this (trim switches cut off) they were physically trying to apply more manual trim using the wheels but were unable to presumably due to aerodynamic forces from the high speed (blowback)

3) they switched electric trim back on to try and correct the trim with "manual electric" again, but their trim corrections were less than those in the opposite direction by the re-connected MCAS

So the issue is why their manual electric trim was repeatedly less than sufficient - it now seems possible that the electric trim was also having issues with blowback.


I believe blowback is a high dynamic pressure phenomenon that affects the elevators, not the trimable stabilizer. The effect of high dynamic pressure (i.e., high airspeed) on the stabilizer seems to be to enhance its trim authority (Boeing apparently did not scale its effectiveness to increasing dynamic pressure) -- possibly beyond the pilot's ability to counteract MCAS nose down trim with nose up manual electric trim inputs in the situation where the airplane is significantly out of trim in the nose down direction.
"You're sitting. In a chair. In the SKY!!" ~ Louis C.K.
 
mwmav8r01
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 06, 2019 3:25 pm

I think people are putting too much on one spot or another. There seems to be a lot going on here.

I am a 737 typed pilot with 15000 hrs, i just want to highlight one possible scenario.

The people saying the manual trim didnt work... Do we know that they tried the trim wheel? Im not blaming lack of training or experience just the possibility... In the fog of war its very easy to get tunnel vision. Just maybe they tried the trim switches as the manual trim and not the wheel. It could have happened. I know when i had 300 hrs on the 737 it felt lime my seat was in the aft lav

It also seems that when they trimmed with the switches on it countered the MCAS as it was supposed to. Did they stop trying to trim or did something else happen?

Thanks for your time, and now I will be bashed by Boeing haters and people who want to call me a racist.
 
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speedbored
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 06, 2019 3:29 pm

dragon6172 wrote:
speedbored wrote:
SheikhDjibouti wrote:
If for some reason the pilots maintained pressure on the thumb switch and yet MCAS still activated, then maybe this is the hidden problem Boeing are now trying to solve. :scratchchin:

I suspect that the additional problem Boeing are investigating will be related to the lack of response from the trim system to the pilots electric trim command at 5:40:15, when the aircraft was still considerably below Vmo. Compare the pitch trim response to the response seen to a slightly shorter trim commands at ~5:39:20, or ~5:38:50. Why was the response at 5:40:15 almost non-existant?

Flaps. The main electric trim moves slower when flaps are retracted. With flaps retracted the thumb switches move trim at about the same speed as autopilot trim (MCAS). With flaps extended the thumb switches move trim faster. At 5:39:20 and 5:38:50 the flaps are extended. At 5:40:15 flaps are retracted.

So the trim movement at 5:40:15 seems less because it moves slower and they let go of the trim switch. The question is why are the pilot commanded nose up trim inputs so short, before trim is cutout, and then after it is turned back on.

That makes sense, and would explain why the trim rate during the longer electric trim command at ~5:40:30 has a shallower gradient. But at 5:40:15 it is as good as non-existant.
 
SimonL
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 06, 2019 3:33 pm

mwmav8r01 wrote:
I think people are putting too much on one spot or another. There seems to be a lot going on here.

I am a 737 typed pilot with 15000 hrs, i just want to highlight one possible scenario.

The people saying the manual trim didnt work... Do we know that they tried the trim wheel? Im not blaming lack of training or experience just the possibility... In the fog of war its very easy to get tunnel vision. Just maybe they tried the trim switches as the manual trim and not the wheel. It could have happened. I know when i had 300 hrs on the 737 it felt lime my seat was in the aft lav

It also seems that when they trimmed with the switches on it countered the MCAS as it was supposed to. Did they stop trying to trim or did something else happen?

Thanks for your time, and now I will be bashed by Boeing haters and people who want to call me a racist.


Based on the preliminary report i would say that yes - they used the wheel.

And if you just the right tone people will not call you a racist or whatever. And imo you did. If you for ex. write "those 3rd world pilots probably didnt knew how to manually trim" then it would have been different...
 
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PixelFlight
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 06, 2019 3:35 pm

MD80Ttail wrote:
xmp125a wrote:
MD80Ttail wrote:
I have stated this before but no one has discussed.....if I was in the ET cockpit...and I had considered this before the ET crash after learning from the lion accident.....I would have lowered flaps to disable the MCAS while still allowing use of the electric trim. Thoughts?


You would tear off the flaps IF you could even extend them at unsafe aerodynamic pressure (I would assume system does not allow that). Even worse, you would partially tear of only one of them, sending plane into unrecoverable spin and end up as pile of smoking debris on the ground, with investigators wondering what the hell were you doing when extending flaps at 300kts, let alone 400kts.

http://www.b737.org.uk/flapspeedschedule.htm¡

Are you really an airline pilot?!



Wow. Can’t believe I have to explain in such detail. The Mcas issue started when flaps were retracted. One of the basic rules of flying is if you take an action and the plane doesn’t like it undo said action. The IAS problems started immediately after take off and the MCAS problems where flaps were retracted. I would have immediately redeployed the flaps after retracting them and having an issue -or- would have never retracted them in the beginning in this situation knowing it would engage MCAS. Which they should have known after the Lion crash. Then fly pitch and power for said configuration. Before the flaps “rip” off you will get some nice buffeting as a warning btw.

It’s frustrating today every little detail has to be explained. One would think the premise is easy to understand.

It's now clear that the procedure you propose (flaps not up + manual electric stab trim) is by far superior to anything Boeing have produced yet in case of AOA disagree on a 737 MAX with MCAS v1.
:stirthepot: 737-8 MAX: "For all speeds higher than 220 Kts and trim set at a value of 2.5 units, the difficulity level of turning the manual trim wheel was level A (trim wheel not movable)." :stirthepot:
 
MSPNWA
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 06, 2019 3:41 pm

SimonL wrote:
Based on the preliminary report i would say that yes - they used the wheel.


What do you see in the report that makes you think that?
 
dragon6172
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 06, 2019 3:52 pm

speedbored wrote:
dragon6172 wrote:
speedbored wrote:
I suspect that the additional problem Boeing are investigating will be related to the lack of response from the trim system to the pilots electric trim command at 5:40:15, when the aircraft was still considerably below Vmo. Compare the pitch trim response to the response seen to a slightly shorter trim commands at ~5:39:20, or ~5:38:50. Why was the response at 5:40:15 almost non-existant?

Flaps. The main electric trim moves slower when flaps are retracted. With flaps retracted the thumb switches move trim at about the same speed as autopilot trim (MCAS). With flaps extended the thumb switches move trim faster. At 5:39:20 and 5:38:50 the flaps are extended. At 5:40:15 flaps are retracted.

So the trim movement at 5:40:15 seems less because it moves slower and they let go of the trim switch. The question is why are the pilot commanded nose up trim inputs so short, before trim is cutout, and then after it is turned back on.

That makes sense, and would explain why the trim rate during the longer electric trim command at ~5:40:30 has a shallower gradient. But at 5:40:15 it is as good as non-existant.

The trim input at 5:40:15 is about two seconds in length, so I'd expect to see around 0.5 to 0.6 units of trim movement. To me the FDR trace shows movement on the low end of that.
Phrogs Phorever
 
kalvado
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 06, 2019 4:06 pm

PixelFlight wrote:
MD80Ttail wrote:
xmp125a wrote:

You would tear off the flaps IF you could even extend them at unsafe aerodynamic pressure (I would assume system does not allow that). Even worse, you would partially tear of only one of them, sending plane into unrecoverable spin and end up as pile of smoking debris on the ground, with investigators wondering what the hell were you doing when extending flaps at 300kts, let alone 400kts.

http://www.b737.org.uk/flapspeedschedule.htm¡

Are you really an airline pilot?!



Wow. Can’t believe I have to explain in such detail. The Mcas issue started when flaps were retracted. One of the basic rules of flying is if you take an action and the plane doesn’t like it undo said action. The IAS problems started immediately after take off and the MCAS problems where flaps were retracted. I would have immediately redeployed the flaps after retracting them and having an issue -or- would have never retracted them in the beginning in this situation knowing it would engage MCAS. Which they should have known after the Lion crash. Then fly pitch and power for said configuration. Before the flaps “rip” off you will get some nice buffeting as a warning btw.

It’s frustrating today every little detail has to be explained. One would think the premise is easy to understand.

It's now clear that the procedure you propose (flaps not up + manual electric stab trim) is by far superior to anything Boeing have produced yet in case of AOA disagree on a 737 MAX with MCAS v1.

Flaps extension can produce additional nose down pitch, extra forces on a coloumn and stabilizer. That is when there is another pitch down problem. If blowback is the thing, it will make things worse.
Is it bad enough of effect?
 
mwmav8r01
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 06, 2019 4:23 pm

MSPNWA wrote:
SimonL wrote:
Based on the preliminary report i would say that yes - they used the wheel.


What do you see in the report that makes you think that?


I dont see it. I coulda missed it.

Do you agree thats plausable? Ive never heard of the trim wheel not working. Though it isnt used much.
 
morrisond
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 06, 2019 4:24 pm

mandala499 wrote:
[photoid][/photoid]
morrisond wrote:
You do understand the normal speed for the 737 is 230 Knots indicated? Close to Vmo would be way out of the normal operating range but still within the flight envelope - Vmo would be the speed you would not really want to above or get near too while descending.

You do realize/understand the normal climb / descent speed for a 737 above 10,000ft is 280kts or 0.76M (for NG and Max, 0.72 or 0.74 for the Classics) whichever is lower? (indicated airspeed)


Serves me right for going off of memory and trying to follow and respond to something on my phone.
 
morrisond
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 06, 2019 4:33 pm

speedbored wrote:
morrisond wrote:
They were 8,000’ AGL - which while low is still sufficient altitude to try a few things - they were not 1,000’ AGL as speculated and repeated to me before this thread was started.

No, they were not. They never even got more than ~6,500ft above the airport elevation. The data is there in the interim report; you don't have to make it up.

At the point when MCAS kicked in, the aircraft was at roughly 1,000ft AGL


Yes - you are right on the 6,500 - reading on my phone again - It looked like they reached about 16,000' not the about 14,000'.

6,500' is still quite q bit of room.

I now MCAS kicked in the first time at 1,000' AGL - I was referring to the second time - where people we're saying that they were only 1,000' AGL and then only had 40 seconds to find a solution before crashing. They did well to get it up to 6,500 AGL.
 
morrisond
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 06, 2019 4:43 pm

mwmav8r01 wrote:
MSPNWA wrote:
SimonL wrote:
Based on the preliminary report i would say that yes - they used the wheel.


What do you see in the report that makes you think that?


I dont see it. I coulda missed it.

Do you agree thats plausable? Ive never heard of the trim wheel not working. Though it isnt used much.



Hi mwmav8r01 - Yes that is plausible. The time from when the Pilot asked the Co-pilot to try Manual was only 8 seconds. The pilots eyes would have been on the Instruments or outside the cockpit and not looking at what the FO was doing.

You would have to think if he(FO) was having physical difficulty moving it he would have asked for help and not given up after 8 seconds - just like the pilot was asking for help with the control column from time to time.



As a 15,000 hour 737 Pilot what do you think of my possible scenario from the previous page?

Copied below:

Sorry - but Colgan crashed because the Pilot followed the incorrect stall recovery procedure - he didn't know how to fly a T-tail - they were most likely going down even without the flaps being raised.

However It does bring up a good point - The Pilot didn't know what the first officer was doing or vice-versa.

In the case of ET302 that could have been what transpired in the last few seconds in the reverse.

I'm not saying this happened but it is Plausible and fits the timeline as they were faced with an impossible situation - please take this as a discussion topic and not me blaming the pilots. I'm really just trying to understand what happened and what could be done better - through better training.

From earlier in the flight we do know that it was the FO who brought up "both Trim Cutoff Switches to Off"

Thereafter there is no discussion of MCAS - the Memo or anything which is very weird. Wouldn't a normal reaction after you figure something out to remark to basically say Eureka! I figured it out - it was MCAS just like Lionair. There is no discussion at all. You would think something like this would be in the discussion of the flight history.

It is possible the Captain was not familiar with the Memo and due to the FO's lack of experience he was reticent to bring it up as he probably assumed the Captain knew all about it.

There is no back and forth in the cockpit according to the printed flight history in the report - the FO just waited for commands from the Pilot.

The First Officer had just been through the Sim (end of Jan) so presumably got some training on MCAS procedures. The Pilot was scheduled too after the fateful flight.

So you have one person in the cockpit who possibly knew the procedures (FO) and one who possibly didn't and really didn't understand what was going on which is understandable if they didn't have the proper training.

Then in the final seconds the Pilot not knowing that turning on Electric Trim again was a big no-no and the FO who can't see what the Captain is doing or bowing to Authority and not speaking up says nothing when the Captain reaches over and reenergizes the Electric trim and tries it again - the Captian not knowing that he should turn it off right away (the Co-Pilot might have assumed he would) but by that time it is too late.

As they are travelling so fast there is no time to react from MCAS again.

One final comment - it is mentioned in the crash report that the throttle levers were never moved from 94% N1 the whole flight.

Over on the other forum a 737 Pilot did point out that small changes in throttle (a few percent) would have literally no effect on the nose pitching down.

I know they were faced with an impossible situation - but with all the overspeed warnings - don't you think they would have tried to pull it back a least a few percent to see the effect when they could both pull to offset it and if didn't work they could have pushed the throttle up again? They did have about 6'500' of altitude at that point.

Again - I am not blaming the pilots - I consider this Boeing's big screwup along with a fault in the Worldwide training system.

Please take this as a discussion topic to help us all understand better what happened.
 
kalvado
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 06, 2019 4:43 pm

morrisond wrote:
speedbored wrote:
morrisond wrote:
They were 8,000’ AGL - which while low is still sufficient altitude to try a few things - they were not 1,000’ AGL as speculated and repeated to me before this thread was started.

No, they were not. They never even got more than ~6,500ft above the airport elevation. The data is there in the interim report; you don't have to make it up.

At the point when MCAS kicked in, the aircraft was at roughly 1,000ft AGL


Yes - you are right on the 6,500 - reading on my phone again - It looked like they reached about 16,000' not the about 14,000'.

6,500' is still quite q bit of room.

I now MCAS kicked in the first time at 1,000' AGL - I was referring to the second time - where people we're saying that they were only 1,000' AGL and then only had 40 seconds to find a solution before crashing. They did well to get it up to 6,500 AGL.


Looks like they were thinking exactly the same way, up there and tried one thing. It didn't quite work, though, and they died in 60 seconds.
 
SimonL
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 06, 2019 4:51 pm

mwmav8r01 wrote:
MSPNWA wrote:
SimonL wrote:
Based on the preliminary report i would say that yes - they used the wheel.


What do you see in the report that makes you think that?


I dont see it. I coulda missed it.

Do you agree thats plausable? Ive never heard of the trim wheel not working. Though it isnt used much.



When they captain asks if the trim is working and the the FO replies "no, should i try manual trim", its clearly suggests that they did try the wheel since they only have 2 ways to trim the plane. And its also a bit too basic to forget.

And as was shown earlier: the trim wheels are under certain conditions very hard to use.
 
Planetalk
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 06, 2019 4:52 pm

MD80Ttail wrote:
Since this thread is all over the place....I can’t find the quote... it’s back a ways.....but someone made a comment about the pilot not understanding his plane in 587. It was Airbus and to some extent AA that didn’t understand the plane. The FO...PF...I think his name was Stan Mollen (so) understood very well exactly what he was taught and practiced and further executed what he was taught and practiced. The plane was below Va. Until this accident every pilot in the world was taught at or below Va you have full use of all control surfaces to their maximum extent and structurally the aircraft will safely handle maximum deflection of all control surfaces.

Airbus...oh wait didn’t even think about this...HID the engineering and design facts, flaws, from the airlines and pilots.....the vertical stab wasn’t strong enough to withstand full deflection of control surfaces at or below Va.

We can argue he shouldn’t have been doing river dance with the pedals. His actions do seem overly aggressive to me. However, up until that point in avaiation history Va meant do whatever you needed or wanted with control inputs without worry of anything bad happening.

I remember....stupidly now...pounding the pedals to watch the tail wag on the Piper Tomahawk. It was stupid I agree but I was much much younger and inexperienced then but I had no worry about tail breaking off because I trusted the manufacturer and trusted what Va meant. Great fun to have your pax watch the tail wag. Again I was young and stupid. Probably had 100-200hrs TT then. Oh wait. Today I could be flying mainline with those hours. :)


And there it is. That one wasn't the pilots fault. That was on Airbus. Of course. Actually all other pilots in the world except him and you knew exactly not to do that. Well maybe others at American Airlines as they were for some bizarre reason training that.

As for 'trusting the manufacturer' you have you read the report? IlYou know it failed beyond design limits right? A Boeing may have failed sooner. Or do you not trust American investigators? I can't believe this nonsense still comes out about that crash. American pride is a fragile thing hey. Please. Stop. Its embarrassing.
 
dragon6172
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 06, 2019 5:02 pm

SimonL wrote:
mwmav8r01 wrote:
MSPNWA wrote:

What do you see in the report that makes you think that?


I dont see it. I coulda missed it.

Do you agree thats plausable? Ive never heard of the trim wheel not working. Though it isnt used much.



When they captain asks if the trim is working and the the FO replies "no, should i try manual trim", its clearly suggests that they did try the wheel since they only have 2 ways to trim the plane. And its also a bit too basic to forget.

And as was shown earlier: the trim wheels are under certain conditions very hard to use.

I agree that this shows that there was an attempt to use manual trim wheel. But how it is worded is odd:

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.


This takes place a full minute after the stab trim cutout switches were used. So the captain asks if the trim is working... and the FO replies no should I try manual. What does the FO mean by trim isn't working? It wouldn't make sense for it to mean... the trim wheel isn't working, should I try the trim wheel?
Phrogs Phorever
 
sgrow787
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 06, 2019 5:30 pm

WIederling wrote:
sgrow787 wrote:
So I was able to find the AD linked to the ADIRU Wikipedia entry ....t


Interesting. what they don't tell is what changing of the polycarbonate cover and the ladder
effects ( beyond avoiding ADIRU errors :-) ( final solution replacing ADIRU with a newer "fixed" model)

Was it a cooling issue, vibration causing connector contacts to "flutter", something else ?


I would imagine a missing screw that mounts the ADIRS to a cabinet shelf would be enough to cause intermittent connection issues, possibly with power, and during certain attitudes and g forces (ie during takeoff). But the important thing is the EASA AD which shows evidence that a faulty ADIRU could cause the symptoms seen on the both 737 Max crashes: erratic airspeed and AOA data:

http://rgl.faa.gov/Regulatory_and_Guida ... -19-14.pdf (posting same link here)

Investigation results highlighted that at the time of the event, the Air Data Reference 1
(ADR) part of ADIRU1 was providing erroneous and temporary wrong parameters in
a random manner. This abnormal behavior of the ADR1 led to several consequences
such as unjustified stall and over speed warnings, loss of attitude information on
Captain Primary Flight Display (PFD) and several ECAM warnings. Among the
abnormal parameters, the provided Angle of Attack (AoA) value was such that the
flight control computers commanded the sudden nose down movement.


Imagine if it was the Airbus A330 that had a faulty mount issue that presented itself during takeoff (instead of at 32000 ft as reported). Would they have found themselves in the same spotlight for having a anti-stall system shoving the nose down at low altitude? Interesting thought to say the least, but that's for another discussion. Airbus planes aren't falling out of the sky, at least not at the rate that the Boeing Max is.

Elsewhere in the EASA AD it mentions a software update to the FCC:

Since that [EASA] AD was issued, new FCPC software standards have been
developed that will inhibit autopilot engagement under unreliable airspeed conditions.


That's similar to what is happening now with Boeing. The difference is that Airbus didn't have an inherent stability problem in their wing/engine design. So the risk of stall during manual flight is significantly less in their case.
Just one sensor,
Oh just one se-en-sor,
Just one sensor,
Ooh ooh oo-ooh
Oo-oo-ooh.
 
WIederling
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 06, 2019 5:46 pm

sgrow787 wrote:
WIederling wrote:
sgrow787 wrote:
So I was able to find the AD linked to the ADIRU Wikipedia entry ....t


Interesting. what they don't tell is what changing of the polycarbonate cover and the ladder
effects ( beyond avoiding ADIRU errors :-) ( final solution replacing ADIRU with a newer "fixed" model)

Was it a cooling issue, vibration causing connector contacts to "flutter", something else ?


I would imagine a missing screw that mounts the ADIRS to a cabinet shelf would be enough to cause intermittent connection issues, possibly with power, and during certain attitudes and g forces (ie during takeoff). But the important thing is the EASA AD which shows evidence that a faulty ADIRU could cause the symptoms seen on the both 737 Max crashes: erratic airspeed and AOA data:

http://rgl.faa.gov/Regulatory_and_Guida ... -19-14.pdf (posting same link here)

Investigation results highlighted that at the time of the event, the Air Data Reference 1
(ADR) part of ADIRU1 was providing erroneous and temporary wrong parameters in
a random manner. This abnormal behavior of the ADR1 led to several consequences
such as unjustified stall and over speed warnings, loss of attitude information on
Captain Primary Flight Display (PFD) and several ECAM warnings. Among the
abnormal parameters, the provided Angle of Attack (AoA) value was such that the
flight control computers commanded the sudden nose down movement.


Imagine if it was the Airbus A330 that had a faulty mount issue that presented itself during takeoff (instead of at 32000 ft as reported). Would they have found themselves in the same spotlight for having a anti-stall system shoving the nose down at low altitude? Interesting thought to say the least, but that's for another discussion. Airbus planes aren't falling out of the sky, at least not at the rate that the Boeing Max is.

Elsewhere in the EASA AD it mentions a software update to the FCC:

Since that [EASA] AD was issued, new FCPC software standards have been
developed that will inhibit autopilot engagement under unreliable airspeed conditions.


That's similar to what is happening now with Boeing. The difference is that Airbus didn't have an inherent stability problem in their wing/engine design. So the risk of stall during manual flight is significantly less in their case.


Isn't the primary difference that Airbus FBW has a sane fall back escalation strategy implemented on input faults?
( With the outlier being the QF dive bomber where the ADIRU produced an intermittent error that was supposed to
be suppressed in the ADIRU? )
Murphy is an optimist
 
MSPNWA
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 06, 2019 5:49 pm

sgrow787 wrote:
That's similar to what is happening now with Boeing. The difference is that Airbus didn't have an inherent stability problem in their wing/engine design. So the risk of stall during manual flight is significantly less in their case.


And neither does the Boeing. This "inherent instability" misinformation has got to end.
 
morrisond
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 06, 2019 5:50 pm

SimonL wrote:
mwmav8r01 wrote:
MSPNWA wrote:

What do you see in the report that makes you think that?


I dont see it. I coulda missed it.

Do you agree thats plausable? Ive never heard of the trim wheel not working. Though it isnt used much.



When they captain asks if the trim is working and the the FO replies "no, should i try manual trim", its clearly suggests that they did try the wheel since they only have 2 ways to trim the plane. And its also a bit too basic to forget.

And as was shown earlier: the trim wheels are under certain conditions very hard to use.


That's not quite what was said.

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.

To me that could very well be the Pilot asking the FO to Manually try the electric trim. But it's not a great sentence so it could be interpreted many ways.

In any case he only tried for 8 seconds and the FO never asked the Pilot to help try cranking - which you assume he would if it was too hard to move.
 
sgrow787
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 06, 2019 6:14 pm

MSPNWA wrote:
sgrow787 wrote:
That's similar to what is happening now with Boeing. The difference is that Airbus didn't have an inherent stability problem in their wing/engine design. So the risk of stall during manual flight is significantly less in their case.


And neither does the Boeing. This "inherent instability" misinformation has got to end.


If there wasn't a stability issue inherent in the Max, then why was MCAS introduced for an airframe that is identical to previous 737 models? Because it's identical with exception to the engine size and placement on the wings.

Oh wait, don't tell me.... to make a safe plane safer!!
Just one sensor,
Oh just one se-en-sor,
Just one sensor,
Ooh ooh oo-ooh
Oo-oo-ooh.
 
Planetalk
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 06, 2019 6:35 pm

mandala499 wrote:
speedbored wrote:
I still do not believe it, because it is not true. At no point was the aircraft ever below FL050, not even while still on the runway.

Take note of the phase of flight that the pilots were in (climb - they were trying to get to 14,000ft), and the altitude they were actually at, and look at the pitch and power settings again.

Regardless of the tables, it is clear from the CVR recordings of overspeed warnings, that the pilots maintained an airspeed within the limits of the airframe for at least the first half of the flight, until they really started to struggle with, and get distracted by, controlling the aircraft. Even then, the overspeed was minor and intermittent according to one side of the aircraft, When presented with multiple different issues, and expending considerable effort on trying to keep the nose up (the overspeed warnings don't kick in until ~80 seconds after both pilots start pulling hard back on the yokes), the pilots have to prioritise what they work on.

Yeah, well, the idea of reducing N1 to 75% is... well... you know...

For the benefit perhaps Morrisond...
Climb at flaps up at unreliable airspeed, as we know, is at max climb thrust (N1 way over 75%), with pitch at 9.5 or more degrees, for a 737-800... The max would have similar numbers...

75% N1 is for cruise with unreliable airspeed at 15000ft... pitch 3.5, N1 75%... and that is for LEVEL flight...

The overspeed warnings, probably came from not reducing the thrust once they wanted to go level... but then, given what they were faced with, am not surprised they didn't end up doing a pitch and power for level flight, because they were task saturated in getting control of the aircraft.

For the Lion Air, both 043 and 610 they didn't overspeed... the question is, why did ET302 have overspeed? Not saying who/what's wrong, but important to understand what went on in the mind of the pilot and what he was trying to prioritize at the time.

asdf wrote:
DIRECTIVE:

in emergency use the hand break to reduce speed of the car

NOTE:

we recommend you to stop the car before you apply hand break

Spot on!

MD80Ttail wrote:
That’s not what I said.....when flaps were retracted the problems started. I would have redeployed the flaps immediately while still at a safe speed. I have been reading here 10 plus years and finally made an account...but the whole forum has become like the news. Pick one word and focus on it to try and make a point. I never suggested deploying the flaps at an unsafe speed. My point was I would have wanted electric trim and no MCAS. Understanding the system after the Lion crash I would have immediately redeployed flaps which should give me what I want.

I agree with this. The crew of 610 did redeploy flaps when MCAS initially played up... but they retracted it again. The mindset flow goes with your saying of "if you do somthing in a plane and it immediately doesn’t like what you did go to back to prior config"... And before anyone has a go at you for this, let me also say, that, this is not monday morning quarterbacking like some would like to accuse you of.

SheikhDjibouti wrote:
This is probably my fault for not spelling out my main point clearly enough.
The "something else" was autopilot randomly disengaging.
If flaps retraction had been the only action in this 15 second window, MCAS would not have activated at 05:40:00

The autopilot disengaging is likely to be due to the MCAS wanting to engage. After all, if you set your autopilot to a selection where you would cause a stall, you'd want it to disengage... not sure of the detailed logic of the 737 Autopilot in the realms of near stall, plus the addition of MCAS on the Max on top... but just by common sense, you'd want the MCAS to disengage the A/P and then command trim nose down if you're in an actual stall... especially if the A/T isn't disengaged.

SheikhDjibouti wrote:
Captain Hindsight with a possible answer here;

1. Re-engage stab trim cut-out
2. Immediately (or even sooner than that!) use thumb switches, and continue to depress the thumb switch to prevent MCAS function.(*)
3. Now, in conjunction with the electric motor attempting to move the stabiliser, both pilots crank the manual trim wheel
4. You now have one electric motor plus two pilots attempting to move the jackscrew
5. If that fails; pray.

You mean 1 = provide power back to the stab trim? :)
I really wonder what Boeing was thinking, having the yoke in the aft (nose up) position and trying to manually crank the trim wheel (especially with heavier than normal forces), isn't an easy walk in the park for some.
What the crew of 302 tried to do was probably what you said above, except for #3, because I think just use the thumb switch for the electric trim should be enough but they needed to do it immediately after reengaging power to the stab trim.
I think the investigation will go deeper into this...

MD80Ttail wrote:
Two. Why didn’t the pilots up trim inputs time out MCAS allowing for the electric trim to be shut off after the pilots had commanded an acceptable trim condition? When conditions changed and the pilots needed more trim ok from what I’ve read and learned the manual trim wheel maybe was useless. That’s a Huge concern. No plane should ever be designed that can’t be manually trimmed.

I think the AD was badly worded that caused pilots reading it, to think, "OK I'll cut it off immediately"... and then lower down, it says, "you may use electric trim to reduce the load forces" (or something like that)... BUT HECK! YOU TOLD ME TO CUT IT OFF !!!!

The lack of emphasis to retrim the aircraft prior to cutting out the stab trim within the AD's wording and content structure, is my guess as being the culprit.

Oh hang on, is someone going to accuse me of being on Boeing's or FAA's payroll for saying that?


Just want to say thank you Mandala for all the time and information you give us here, your insights are incredibly valuable and your patience frankly incredible. I imagine LionAir was tough on you so just wanted to say thanks and that you are appreciated.
 
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qf789
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 06, 2019 7:09 pm

Again debate the topic and keep personal comments towards one another out of the discussion
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Moose135
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 06, 2019 7:12 pm

sgrow787 wrote:
If there wasn't a stability issue inherent in the Max, then why was MCAS introduced for an airframe that is identical to previous 737 models? Because it's identical with exception to the engine size and placement on the wings.

MCAS was added so that the Max handled the same as the NG, which the airlines wanted so that it could be flown with the same type rating. Without MCAS, the Max would still be safe, but pilots would need additional training and certification, something that operators didn't want to spend money on. That has been explained a number of times in these threads.
KC-135 - Passing gas and taking names!
 
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speedbored
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 06, 2019 7:16 pm

Moose135 wrote:
sgrow787 wrote:
If there wasn't a stability issue inherent in the Max, then why was MCAS introduced for an airframe that is identical to previous 737 models? Because it's identical with exception to the engine size and placement on the wings.

MCAS was added so that the Max handled the same as the NG, which the airlines wanted so that it could be flown with the same type rating. Without MCAS, the Max would still be safe, but pilots would need additional training and certification, something that operators didn't want to spend money on. That has been explained a number of times in these threads.

Yes.

It is the addition of MCAS that gave the MAX stability issues.
 
Waterbomber2
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 06, 2019 7:46 pm

morrisond wrote:
SimonL wrote:
mwmav8r01 wrote:

I dont see it. I coulda missed it.

Do you agree thats plausable? Ive never heard of the trim wheel not working. Though it isnt used much.



When they captain asks if the trim is working and the the FO replies "no, should i try manual trim", its clearly suggests that they did try the wheel since they only have 2 ways to trim the plane. And its also a bit too basic to forget.

And as was shown earlier: the trim wheels are under certain conditions very hard to use.


That's not quite what was said.

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.

To me that could very well be the Pilot asking the FO to Manually try the electric trim. But it's not a great sentence so it could be interpreted many ways.

In any case he only tried for 8 seconds and the FO never asked the Pilot to help try cranking - which you assume he would if it was too hard to move.


If you put yourself in that situation, you should visualise it better.
They cut off the electric trim, captain still asks to try trimming because he wants to make sure that it isn't working, or perhaps to try to see if the manual electric trim can override the cutoff switch.

The trim wheel should however override the switch and be able to get cranked. It takes 1 second to start cranking a trim wheel. In 8 seconds you can reach full arm force to crank it. If the FO did get any movement, he would have asked the captain to help him crank it, but remember that the captain was busy pulling on the stick, so he wasnt going to let go of that to help crank something that is not moving to begin with.

It's pretty certain that the FO did try to move that wheel and failed to get any movement.
 
Planetalk
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 06, 2019 8:39 pm

Moose135 wrote:
sgrow787 wrote:
If there wasn't a stability issue inherent in the Max, then why was MCAS introduced for an airframe that is identical to previous 737 models? Because it's identical with exception to the engine size and placement on the wings.

MCAS was added so that the Max handled the same as the NG, which the airlines wanted so that it could be flown with the same type rating. Without MCAS, the Max would still be safe, but pilots would need additional training and certification, something that operators didn't want to spend money on. That has been explained a number of times in these threads.


Actually no, you're getting things slightly confused. MCAS was required to meet certification requirements, even after other aerodynamic modifications were made to try and solve the problem caused by the new engines, without MCAS there is an abnormal pitch up that is not allowable. So MCAS was added. See here for an explanation http://www.b737.org.uk/mcas.htm

Separately to that Boeing then made a case, heavily influenced by the airlines, that MCAS didn't necessitate a different type rating. And from reports on the certification process, did not inform the FAA of the true extent of the movement MCAS can command.

Perhaps worth reposting this for a fuller insight https://www.seattletimes.com/business/b ... air-crash/

The article gives a clear picture of why the whole thing is under criminal investigation and Boeing have accepted they bear some responsibility which is actually very unusual for a manufacturer after a crash. Although some will still insist there is nothing wrong with the plane. :banghead:
Last edited by Planetalk on Sat Apr 06, 2019 8:53 pm, edited 1 time in total.
 
KingOrGod
Posts: 154
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 06, 2019 8:45 pm

MD80Ttail wrote:
Seriously? I don’t bow to anyone and no American bows. We fought a little war called the Revolutionary War to settle that debate.

Look, I fly for a living.


Wow, how to trash your name in one easy step. Giddy up keyboard warrior.
 
smartplane
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 06, 2019 8:55 pm

What's with these repetitively deflecting posts? Hands up those working for a crisis / reputation management PR specialist.
 
mzlin
Posts: 123
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 06, 2019 9:07 pm

Planetalk wrote:
Moose135 wrote:
sgrow787 wrote:
If there wasn't a stability issue inherent in the Max, then why was MCAS introduced for an airframe that is identical to previous 737 models? Because it's identical with exception to the engine size and placement on the wings.

MCAS was added so that the Max handled the same as the NG, which the airlines wanted so that it could be flown with the same type rating. Without MCAS, the Max would still be safe, but pilots would need additional training and certification, something that operators didn't want to spend money on. That has been explained a number of times in these threads.


Actually no, you're getting things slightly confused. MCAS was required to meet certification requirements, even after other aerodynamic modifications were made to try and solve the problem caused by the new engines, without MCAS there is an abnormal pitch up that is not allowable. So MCAS was added. See here for an explanation http://www.b737.org.uk/mcas.htm

Separately to that Boeing then made a case, heavily influenced by the airlines, that MCAS didn't necessitate a different type rating. And from reports on the certification process, did not inform the FAA of the true extent of the movement MCAS can command.

Perhaps worth reposting this for a fuller insight https://www.seattletimes.com/business/b ... air-crash/

The article gives a clear picture of why the whole thing is under criminal investigation and Boeing have accepted they bear some responsibility which is actually very unusual for a manufacturer after a crash. Although some will still insist there is nothing wrong with the plane. :banghead:


Great post. Would be nice if everybody could read that Seattle Times article before asking the same questions or spreading the same wrong guesses/assumptions repeatedly.
 
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PW100
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 06, 2019 9:31 pm

mandala499 wrote:
mzlin wrote:
It is the final paragraph in this directive which is a restatement of the runaway stabilizer memory checklist:

Thanks... I think we have a problem in how this MCAS thing is trained...
I think the crew of ET followed this AD...
Going from the top to bottom.. Cutout... was told to cut out for the remainder of the flight... and then down at the bottom, "by the way, you can use the electric stabilizer before the cutout if it feels heavy or hard to move the stab trim"... Oh, OK, let's try that... then MCAS starts acting up...


PW100 wrote:
As you can see in ALL of my posts, I continue asking questions as to why the crew did this, did that, stopped uptrimming way before the control column was balanced in pitch. Why they reinstated electric trimming. Trying to find answers.
The only thing I see from you, is that crew made a lot of mistakes. I have not seen one single effort from your side trying to answer these important questions.

See the above (and the reply by MZLIN at $4492)


Hi 499,
Not sure what you were suggesting here.
My post was a reaction to some that implied the crew made several mistakes:
1) Not performing electric uptrim prior to hitting the cut out switches (as [i] suggested[i] by the AD);
2) Re-instating MCAS by reversing cut-out switches (in direct conflict with the AD);
3) Trim-control issues were a result of the crew allowing the aircraft to exceed Vmo.

I replied to that that I'm not sure we can conclude that as mistakes, perhaps they had no other choice. Please allow me to explain.

1)
Per the FDR chart, every instance of uptrim (after flap retraction) ended well before the control column was balanced in pitch. Why did they stop trimming before the control column was balancedin pitch? There were a total of four electric uptrim events when the control column was heavy. But each instance stopped/ was cut-out well before the control column was anywhere near being balanced (if I may extrapolate Ctrl Column Pos to control column force). Why would the PF stop electric uptrim if with a heavy control column?

Also, the observation was that throwing the cut-out switches was preceeded with the longest recorded uptrim was performed. So this seem to be very much in line with the AD and instruction to use electric uptrim prior to hitting the cut out switches. But again, why did the PF stop uptrimming before the control column was balance din pitch? I offered two theroies:
a) the PF was in fact still uptrimming, but the cut-out switches were thrown (by PM) while trimming was still in progress. This could be seen as a crew CRM issue, lack of communication;
b) Could it be that the uptrim was stopped as the motor reached its max torque limit, due to aerodynamic loading of the elevator? Such mechanism has now been reported by Leeham as well as Ostrower.
Conclusion: crew mistake? Not sure, in fact, don't think so.


2)
Why did they re-instate electric trimming? Offered theory was that the crew started reaching their physical limitations in maintain back force on control column (lactic acid setting in their muscles) and they were desperately searching for option to reduce control column back force. Re-instating electric trimming would do that (theoretically). And we can see two (very short) up trim commands at 05:43:10. But these were both very short. Again, WHY? Why on earth would the crew stop uptrimming if there was so much back force on the control column? Possible answer, as per 1) above: electric trim motor could not overcome aerodynamic forces?
Conclusion? Crew error? Probably not. More an act of desperation, rather than "not following AD procedures".

3)
It was suggested that since the crew allowed the plane to exceed Vmo, they found themselves in a opposition that both electric trimming, as well as manual trimming were non-functional (due to excessive aerodynamic loading of elevator). I believe that the ineffectiveness of electric/manual trimming was already present before exceeding Vmo, a shown by the FDR chart. Both uptrim commands at 05:40:15 and 05:40:30 stop way short of control column being balanced. At this stage Vmo had not been reached, and the aircraft was still within the certified flight envelope. Even here, trimming was apparently not effective in balancing the control column in pitch.
Conclusion: Perhaps the crew should not have allowed the plane to exceed Vmo, but that was inconsequential in the grand scheme of things as they "lost" pitch trim control before reaching Vmo.

So I guess my main question was, and still is, why were the uptrim commands cut short, well before the control column was anywhere near being pitch balanced?
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PW100
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 06, 2019 9:32 pm

MD80Ttail wrote:
SomebodyInTLS wrote:
MD80Ttail wrote:
I have stated this before but no one has discussed.....if I was in the ET cockpit...and I had considered this before the ET crash after learning from the lion accident.....I would have lowered flaps to disable the MCAS while still allowing use of the electric trim. Thoughts?


In overspeed...


That’s not what I said.....when flaps were retracted the problems started. I would have redeployed the flaps immediately while still at a safe speed.


What is the maximum speed allowed for minimum flaps?
When MCAS completed its first cycle, they were closing in on 300 kts, per FDR chart. Would that not be outside flaps operating envelope?
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PW100
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 06, 2019 9:45 pm

MD80Ttail wrote:
marcelh wrote:
MD80Ttail wrote:
The FO didn’t know what he was doing either. Maybe he thought he knew what he was doing.....not his fault. But having a FO with 150-200hrs TOTAL time is literally criminal. At 200hrs TT the plane is flying you....you are not flying the plane.....you are behind the aircraft w 200hrs TT.

I repeat my statement: if lack of training/hours is so criminal, why don’t we read that a NG or A320 has made a crater?



Too many to list.



OK, I'll bite.
I'm curious at your list of NG or A320 craters with 200 hrs FO in the pointy end.

Thanks.


PS. Just to be clear, I'm not arguing with you that 200 hrs FO should not be in the cockpit of a commercial airliner (BTW, this FO had 361 hrs, of which 207 in 737, of which 56 in MAX). Just not (yet) convinced if his junior status was in any way a factor in this accident.

PS2. Regardless of total hours, what do you think of a 151 hrs NG pilot (even if he had 10000 hrs on different type, say A320) converting to MAX?

PS3. In my mind, FIRST we should establish if there were any issues with crew performance. If so, that would be the point we should start looking at FO proficiency, in regards with his limited total hours.
Since that FIRST is a looong way from being certain, discussing FO hrs at this stage is just producing noise and distracting us from establishing FIRST in the first place.
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PW100
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 06, 2019 9:50 pm

mandala499 wrote:
The autopilot disengaging is likely to be due to the MCAS wanting to engage. After all, if you set your autopilot to a selection where you would cause a stall, you'd want it to disengage... not sure of the detailed logic of the 737 Autopilot in the realms of near stall, plus the addition of MCAS on the Max on top... but just by common sense, you'd want the MCAS to disengage the A/P and then command trim nose down if you're in an actual stall... especially if the A/T isn't disengaged.
SheikhDjibouti wrote:
Captain Hindsight with a possible answer here;
1. Re-engage stab trim cut-out
2. Immediately (or even sooner than that!) use thumb switches, and continue to depress the thumb switch to prevent MCAS function.(*)
3. Now, in conjunction with the electric motor attempting to move the stabiliser, both pilots crank the manual trim wheel
4. You now have one electric motor plus two pilots attempting to move the jackscrew
5. If that fails; pray.
You mean 1 = provide power back to the stab trim? :)
I really wonder what Boeing was thinking, having the yoke in the aft (nose up) position and trying to manually crank the trim wheel (especially with heavier than normal forces), isn't an easy walk in the park for some.
What the crew of 302 tried to do was probably what you said above, except for #3, because I think just use the thumb switch for the electric trim should be enough but they needed to do it immediately after reengaging power to the stab trim.
I think the investigation will go deeper into this...

I think they did just that, as seeing TWO instances of uptrim before MCAS kicked in again, but this electric uptrimming did not provide the desired result. Perhaps that threw them off in thinking that electric (up)trimming was not working, thus MACS down trimming would also be not working . . .



mandala499 wrote:
MD80Ttail wrote:
Two. Why didn’t the pilots up trim inputs time out MCAS allowing for the electric trim to be shut off after the pilots had commanded an acceptable trim condition? When conditions changed and the pilots needed more trim ok from what I’ve read and learned the manual trim wheel maybe was useless. That’s a Huge concern. No plane should ever be designed that can’t be manually trimmed.

I think the AD was badly worded that caused pilots reading it, to think, "OK I'll cut it off immediately"... and then lower down, it says, "you may use electric trim to reduce the load forces" (or something like that)... BUT HECK! YOU TOLD ME TO CUT IT OFF !!!!

The lack of emphasis to retrim the aircraft prior to cutting out the stab trim within the AD's wording and content structure, is my guess as being the culprit.

Oh hang on, is someone going to accuse me of being on Boeing's or FAA's payroll for saying that?

The FDR clearly shows a good deal of uptrimming prior to cut out switches. Its not that the crew did not try that. Its that all of their uptrimming was cut short before the control column was pitch balanced. Why is that? Why would the crew stop uptriming if there is still considerable back force required on the column? That just does not make any sense whatsoever. Even for a 200 hrs 361 hrs FO. It very much seems there was another mechanism in play, unknown to the crew, that prevented them somehow from reaching balanced pitch trim condition.
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