Boeing 737 Max8 Aircraft Crashes and Investigations [Part 2] 44

[Alistair_Heaton]

This thread is a continuation of:

thread815-445840


****************************
Another 737 max has crashed during departure in Ethiopia.

To note the data in the picture is intally ground 0 then when airborne is GPS altitude above MSL. The airport is extremely high.

The debris is extremely compact and the fuel burned, they reckon it was 400knts plus when it hit the ground.

Here is the radar24 data pulled from there local site.

It's already being discussed if was another AoA issue with the MCAS system for stall protection.

I will let you make your own conclusions.

 

[waross]

Hi Lionel.
Who is Peter Lemme?
From the links posted by Pete K

https://www.seattletimes.com/business/boeing-aerospace/grand-jury-subpoena-shows-sweep-of-criminal-probe-into-boeings-737-max-certification/[/URL]]After two fatal crashes of Boeing’s 737 MAX, a federal agent served a grand jury subpoena Monday seeking information from an aviation flight-controls expert and consultant as part of a sweeping and aggressive criminal investigation into the jet’s certification.

The expert, Peter Lemme, a Kirkland-based former Boeing flight-controls engineer who is now an avionics and satellite-communications consultant, has no direct personal knowledge of the airplane’s development or certification but he did a detailed analysis of the October crash of a Lion Air 737 MAX. He was extensively cited as an expert in The Seattle Times, subsequently in multiple press accounts, including in The New York Times.

What did Peter Lemme say?

https://www.seattletimes.com/business/boeing-aerospace/boeings-emergency-procedure-for-737-max-may-have-failed-on-ethiopian-flight/[/URL]]Exerpts: But Lemme said the Ethiopian pilots most likely were unable to carry out that last instruction in the Boeing emergency procedure — because they simply couldn’t physically move that wheel against the heavy forces acting on the tail.
“The forces on the tail could have been too great,” Lemme said. “They couldn’t turn the manual trim wheel.”

The stabilizer in the Ethiopian jet could have been in an extreme position with two separate forces acting on it:

MCAS had swiveled the stabilizer upward by turning a large mechanical screw inside the tail called the jackscrew. This is pushing the jet’s nose down.
But the pilot had pulled his control column far back in an attempt to counter, which would flip up a separate movable surface called the elevator on the trailing edge of the tail.

The elevator and stabilizer normally work together to minimize the loads on the jackscrew. But in certain conditions, the elevator and stabilizer loads combine to present high forces on the jackscrew and make it very difficult to turn manually.If after much physical exertion failed, the pilots gave up their manual strategy and switched the electric trim system back on — as indicated in the preliminary reports on the Ethiopian flight — MCAS would have begun pushing the nose down again.
Boeing on Wednesday issued a statement following the first account, published Tuesday night by The Wall Street Journal, that the Ethiopian pilots had followed the recommended procedures.

And in support, there is this information:

https://www.seattletimes.com/business/boeing-aerospace/boeings-emergency-procedure-for-737-max-may-have-failed-on-ethiopian-flight/[/URL]]A local expert, former Boeing flight-control engineer Peter Lemme, recently explained how the emergency procedure could fail disastrously. His scenario is backed up by extracts from a 1982 Boeing 737-200 Pilot Training Manual posted to an online pilot forum a month ago by an Australian pilot.

That old 737 pilot manual lays out a scenario where a much more elaborate pilot response is required than the one that Boeing outlined in November and has reiterated ever since. The explanation in that manual from nearly 40 years ago is no longer detailed in the current flight manual.
...
More detailed instructions that conceivably could have saved the Ethiopian plane are provided in the 1982 pilot manual for the old 737. As described in the extract posted by the Australian pilot, they require the pilot to do something counterintuitive: to let go of the control column for a brief moment.

As Lemme explains, this “will make the nose drop a bit,” but it will relax the force on the elevator and on the jackscrew, allowing the pilot to crank the stabilizer trim wheel. The instructions in the old manual say that the pilot should repeatedly do this: Release the control column and crank the stabilizer wheel, release and crank, release and crank, until the stabilizer is swiveled back to where it should be.

And this:

https://www.seattletimes.com/business/boeing-aerospace/boeings-emergency-procedure-for-737-max-may-have-failed-on-ethiopian-flight/[/URL]]However, a separate analysis done by Bjorn Fehrm, a former jet-fighter pilot and an aeronautical engineer who is now an analyst with Leeham.net, replicates Lemme’s conclusion that excessive forces on the stabilizer trim wheel led the pilots to lose control.

Fehrm collaborated with a Swedish pilot for a major European airline to do a simulator test that recreated the possible conditions in the Ethiopian cockpit.

A chilling video of how that simulator test played out was posted to YouTube and showed exactly the scenario envisaged in the analysis, elevating it from plausible theory to demonstrated possibility.The Swedish pilot is a 737 flight instructor and training captain who hosts a popular YouTube channel called Mentour Pilot, where he communicates the intricate details of flying an airliner. To protect his employment, his name and the name of his airline are not revealed, but he is very clearly an expert 737 pilot.

In the test, the two European pilots in the 737 simulator set up a situation reflecting what happens when the pre-software fix MCAS is activated: They moved the stabilizer to push the nose down. They set the indicators to show disagreement over the air speed and followed normal procedures to address that, which increases airspeed.

They then followed the instructions Boeing recommended and, as airspeed increases, the forces on the control column and on the stabilizer wheel become increasingly strong.After just a few minutes, with the plane still nose down, the Swedish 737 training pilot is exerting all his might to hold the control column, locking his upper arms around it. Meanwhile, on his right, the first officer tries vainly to turn the stabilizer wheel, barely able to budge it by the end.

If this had been a real flight, these two very competent 737 pilots would have been all but lost.

The Swedish pilot says at the start of the video that he’s posting it both as a cautionary safety alert but also to undercut the narrative among some pilots, especially Americans, that the Indonesian and Ethiopian flight crews must have been incompetent and couldn’t “just fly the airplane.”Early Wednesday, the Swedish pilot removed the video after a colleague advised that he do so, given that all the facts are not yet in from the ongoing investigation of the crash of Flight 302.

More detailed instructions that conceivably could have saved the Ethiopian plane are provided in the 1982 pilot manual for the old 737. As described in the extract posted by the Australian pilot, they require the pilot to do something counterintuitive: to let go of the control column for a brief moment.

As Lemme explains, this “will make the nose drop a bit,” but it will relax the force on the elevator and on the jackscrew, allowing the pilot to crank the stabilizer trim wheel. The instructions in the old manual say that the pilot should repeatedly do this: Release the control column and crank the stabilizer wheel, release and crank, release and crank, until the stabilizer is swiveled back to where it should be.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[saikee119]

Who is Peter Lemme?

here

He is a Satcom guru and his in depth knowledge of operating 737 models including Max is generally regarded one of the top experts.

 

[saikee119]

#1. There is no evidence they attempted to operate the manual wheel after throwing the cutout switches.

Page 11 of Preliminary Report last paragraph

"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 is from BBC news
"The pilots' five-minute struggle

08:38 A sensor on the pilot's side falsely indicates that the plane is close to stalling, triggering MCAS and pushing down the nose of the plane
08:39-40 The pilots try to counter this by adjusting the angle of stabilisers on the tail of the plane using electrical switches on their control wheels to bring the nose back up
08:40 They then disable the electrical system that was powering the software that pushed the nose down
08:41 The crew then attempt to control the stabilisers manually with wheels - something difficult to do while travelling at high speed
08:43 When this doesn't work, the pilots turn the electricity back on and again try to move the stabilisers. However, the automated system engages again and the plane goes into a dive from which it never recovered

Source: Ethiopia's Aircraft Accident Investigation Bureau"

#2. The cutout switches appear to have been on right before the plane crashed.

At about 05:43:10 the pilots applied two the Manual (electric) Trim command. Thereafter about 5 to 6 seconds the last MCAS activated and destroyed the plane. This has been interpreted the electrical power had been restored by the pilot in an attempt to replace the manual crank with the Manual (electric) trim.

The initial accident report shows that the pilots held the plane fairly level with the stabilizer almost full down, at 0.4 units (degeees?) long enough to operate it back to 2.3 units. One could conclude from this that there is an amount of force that can counteract it.

If the pilots were able to control the stabilizer they would not have to restore the power to access the Manual (electric) trim.

You can read Peter Lemme's explanation and the Q&A with the pilots on this matter.

 

[LionelHutz]

I misread that line to mean they tried the electric trim again.

Bill - the trim was at 2.1-2.3, not full down so that simulation and any comments about the trim being impossible to move manually when at the full down position simply doesn't match what was being attempted. They certainly didn't attempt to move the wheel during the last dive to recover the plane. So, if you want to keep claiming it was impossible then find something which says the amount the trim needs to be away from the "ideal" before the manual wheel gets too hard to turn. In this case it seems the trim was around 2-2.5* off when they attempted to move the manual wheel.


This is something I found really odd.

At 05:40:12, approximately three seconds after AND stabilizer motion ends, electric trim (from
pilot activated switches on the yoke) in the Aircraft nose up (ANU) direction is recorded on the
DFDR and the stabilizer moved in the ANU direction to 2.4 units. The Aircraft pitch attitude
remained about the same as the back pressure on the column increased.

At 05:40:28 Manual electric trim in the ANU direction was recorded and the stabilizer reversed
moving in the ANU direction and then the trim reached 2.3 units

At 05:43:11, about 32 seconds before the end of the recording, at approximately 13,4002 ft, two
momentary manual electric trim inputs are recorded in the ANU direction. The stabilizer moved in
the ANU direction from 2.1 units to 2.3 units.

Readin the above and looking at the FDR graphs, why did they keep moving the trim adjustment back to around 2.4/2.3 units but never attempt to go further? At one point, they held the trim switch about 9 seconds to get back to 2.3*, but never pressed the switch to go further towards 4.5*.


saikee119 - you totally and completely missed the point of that last comment of mine you quoted. The stabilizer moved to 0.4 degrees and the pilots were able to control the plane and get through it with the plane remaining reasonable level. This makes claims saying it is impossible to keep the plane level with the stabilizer at 1 degree questionable.

 

[Sparweb]

There is no reason (yet) to believe the crew turned the STAB TRIM back on.

I have been seeing some misinterpretations and misunderstandings. I don't want the speculation and assumptions to get out of control. Without saying I'm the best person to explain this, I think I'm in a good position to discuss some of the details about the control system. I hope to forestall any jumping to conclusions about what the crew may or may not have done. While I acknowledge that my own understanding of the 737 is limited, I have been taking the time to read carefully the most authoritative sources of information, so that I may understand it better.

Assumptions that "electric trim" implies MCAS is turned on are incorrect.
Assumptions that "manual" control of a device implies no electric operation are also incorrect.
Even though the 737 is a fairly old aircraft type, it's not only controlled by rods and strings.
The sequence of events told in the preliminary report indicates that the "manual (electric) trim" was used at

The "old" 737's were equipped with autopilot, yaw dampers, mach trim, and approach coupling as standard equipment. These automatic systems are similar to the systems used today, and driven by semiconductor logic that a modern engineer can read and follow. They've probably evolved over the decades, but I don't think they've been replaced outright.

When operated in manual mode, the automatic systems are overridden, as you would expect, but manual doesn't mean "mechanical".

Here's a photo of the relevant controls:

This picture was taken just a few years ago from a 737-400. As you can see from all the glass, it's had an avionics upgrade, but the basic flight controls remain the same.

The 737's all have stabilizer trim wheels on either side of the center console to allow the flight crew to make manual adjustments to the stabilizer. These adjustments are unnecessary when the autopilot is on, and moving the wheels can actually disable the AP if it is.

In the lower center of the photo, you can see the pair of STAB TRIM switches. If they are set to CUTOUT then the autopilot and hence approach coupling cannot engage. Also disconnected by STAB TRIM CUTOUT is the MCAS. What remains available, however, are the manual trim, MACH trim and the Yaw dampers.

Mach trim does what you might assume it does: adjusts the trim slightly for the effects of high speed (the 737's fly up to Mach 0.85 or so). The Yaw dampers compensate for oscillations in the aircraft's lateral direction which happen when slight adjustments are made to its direction. There is no need to override these if the stabilizer trim has trouble (and reasons why you don't want to either).

The aircraft stabilizer and elevator work in a dependent-independent relationship. The stabilizer is the "entire" horizontal tail, which can pitch up or down several degrees. You can see the marks on the fuselage this travel leaves on every 737. When the stabilizer moves, the elevators moves, too. Their relative movements are complex:

(The above photo is from a 737-200. Sorry I have no 737 Max schematics. It is my belief that much of this system is similar on later aircraft, including the Max, but I admit it's an assumption on my part.)

The main driver of the horizontal stabilizer is the trim actuator, which is a screw-jack. It receives commands from trim adjustment wheels on the center console. My understanding is that on the Max, an additional input to this actuator is sent from the MCAS system. When active, the MCAS will move the actuator, adjusting the stabilizer pitch up (which pitches the nose down) and the crew should expect to see the stabilizer wheels spin at the same time.

The elevator is the movable trailing edge of the stabilizer. The main control Yoke operates the elevator, and it is quite true that this is done by steel cables. So when the flight crew "pulls back on the stick" they are indeed pulling on cables and directly moving the elevator. You can also see from the schematic above, there are other systems acting on it, including the mach trim and the autopilot actuators. These make adjustments relative to the position of the cables from the yoke, and the elevator can move under autopilot control without the yoke showing any corresponding movement.

So going back to what happens when the STAB TRIM is set to CUTOUT, the autopilot actuators on the elevator stop working, and so should the MCAS control over the stabilizer trim. But all the other controls do still function.

I believe the ET-AVJ crew had properly set these switches to CUTOUT, and never moved them back. They then wrestled the yoke bring the nose back up, but it took all their personal strength to do so. When one or the other tried a couple of times to reach for the trim wheel on the console, he could only manage a small amount of turn before he had to put his hands back on the yoke to maintain the nose attitude. This was tried twice but the effect was too small. They would have had to accomplish many turns of those wheels to return the stabilizer to a neutral position.



No one believes the theory except the one who developed it. Everyone believes the experiment except the one who ran it.
STF

 

[waross]

Lionel
I'm just going by what Peter Lemme, an acknowledged expert has said, and by the experience of two pilots who "crashed" in a simulator because the forces were too great to overcome.
I also noticed a little note that says that when the plane dives the speed increases and when the speed increases, the control forces increase also.
The speed must be considered as well as the stabilizer position.
And there is the old 1982 flight manual procedure that addresses the extreme control forces that can develop and has a procedure to manually trim the stabilizer when that happens.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[Alistair_Heaton]

"What's your take on the initial report which has a few of us quote confused as to what the pilot actions and thinking was. "

MY main thought is utter "by the grace of god go I"

Some of us call this test pilot territory which basically means that they are in a situation which they have no training for and zero knowledge how to deal with and they can only rely on systems knowledge and experence to try and sort it out. But to be honest no test pilot would be in this situation because there would be multiple cut outs and additional data analysis going on in the back for real time data managment and a load of technicians on the ground monitoring things real time.

I was at a kids party yesturday with another dad who has flown the Max. He is qualified on what we call the 737 classics which is the 300,400,and 500 which is the cockpit detailed above. Also on the new generation NG 737 which is 600,700,800 and 900. The training between the classic and NG is 4 days of ground school followed by 4 sessions in the sim and a new type rating issued to your license.

Before he flew the MAX for the first time he had a call from ops 18 hours before departure telling him to do the Ipad training which took 45mins. The turned up to find his fellow pilot was exactly the same.

He said that he found the MAX to have more handling differences than the transition between Classic and NG.

Now I am an ex engineer and he is a ex session musician. We could only think that the system is mainly for in the event of a go-around where you get high power settings, manual flight control and high alphas and the trim setting is quite far away from your normal departure setting. GO- arounds are trained every 6 months but normally in single engine operation. Dual engine go-arounds we do as part of our low vis training for Cat2 and Cat 3 approaches. So personally I do 3 single engine go-arounds and 2 dual engine go-arounds every 6 months in the sim and the last part of the low viz training is usually an engine fire at 900ft which I always ignore and land then deal with it on the ground in 350m viz and 000 cloud base (you get to see 2 lights of the approach lights at 110 feet and your on the ground 5 seconds later). Real life I have done 2 go-arounds in the last 12 months in a real aircraft. Once due to outside wind limits on a slippery runway at 200 feet and the second was due to another aircraft not clearing the active runway in time for us to land. They are not a big deal although if the aircraft is very light it can be a bit sporty mainly due to the climb performance.

Another point he brought up...

Now because the tail plane is an all moving affair without balance horns they can get an effect where the aerodynamic loads are more than a normal human can pull against and the manual trim does not have enough leaverage to power through even with the handle pulled out the side to help. Boeing have a procedure for dealing with this which is both pilots pull there hardest on the controls and then relax the pressure on them and during the period while the forces are sorting themselves out the trim wheel can be moved and you do that multiple times until your back into the situation that you can again move the trim wheel normally. This is a common procedure on Classics and NG. It takes loads of altitude to sort out. He has done it a couple of times in the sim and he is not a small lad and said they had two 90 kg blokes pulling at the controls with thier feet braced on the instrument panel and the examiner cheering in the back saying go for it and they managed an outstanding comment on there post session form. He said they were lucky to get half a turn out of the trim wheel every pull and it took maybe 5-6 pulls to get it to the point they could move the trim wheel manually.

The Q400 has a fixed plane elevator with balance horns in front of the point of rotation and you can hand fly it manually with full forward trim position and full rear. Which is why I presume it doesn't have a manual trim wheel.

Now none of the above has any technical comment on the crash. I give it to give a picture of what its like in the cockpit and the human factors side of dealing with issues and a general coment on how these things work.

There was an issue with my registration apparently. I would like to state I am not pro any manufactures product, most of my time has been spent in a Handely Page designed aircraft aka the designer of Lancaster Bomber. Built like a brick poo house, lovely to fly but ultimately an under performing heap of an aircraft which realistically shouldn't be flying with paying pax on board these days. The aircraft I really really want to fly is the Boeing 757 with Rolls engines sometimes called the 75 GTI in piloting circles. So I am not anti Boeing in the slightest. But I do think a pilot should be given a safe aircraft with which to operate. My disgust is firmly towards the regualators allowing this situation to develop. And its not just targeted at one countries regulator, world wide they are all as bad as each other these days. They have all de skilled and turned into paper work chasers over the last 20 years. But I am sure sparweb has more experence and knowledge on this subject than I do as a stick monkey. BTW the stick monkey comes from an old bit of banter between Pilots and Technicians. The techs say you can train a monkey to ride a bike but you can't train one to fix it.

 

[Alistair_Heaton]

This is a 737-800 NG cockpit.

And this is the MAX.


"It is my belief that much of this system is similar on later aircraft, including the Max, but I admit it's an assumption on my part."

Its the same, a physical change to the control system would be a step to far for a straight through grandfather certification. It would also trip the balance between new type rating and differences training. I will try and find out if it changed between Classics and NG.

 

[Alistair_Heaton]

After a brief search since my last post here is some of the things I have found which may be of interest.

http://www.737ng.co.uk/B_NG-Flight_Controls.pdf

http://www.b737.org.uk/flightcontrols.htm#Pitch

https://www.satcom.guru/2018/11/stabilizer-trim.html

 

[Sparweb]

Welcome back Alistair,

"It is my belief that much of this system is similar on later aircraft, including the Max, but I admit it's an assumption on my part."

Its the same, a physical change to the control system would be a step to far for a straight through grandfather certification. It would also trip the balance between new type rating and differences training. I will try and find out if it changed between Classics and NG.

That's exactly what was on my mind as I wrote it.
Any drastic change to the flight controls, such as giving the pilots more authority over that big stabilizer, would trigger re-certification.


No one believes the theory except the one who developed it. Everyone believes the experiment except the one who ran it.
STF

 

[waross]

Has anyone else noticed that even after the loss of over 100 lives, neither Boeing nor the FAA seemed to feel a need to verify the failed procedure in a simulator before releasing it?


Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[itsmoked]

Bill; after reading about "forces increasing", "hard to turn trim wheels", etc., I suspect it could take months to build a simulator true-enough to be suitable for 'testing' as compared to one that might be "suitable for training".

Keith Cress
kcress -

http://www.flaminsystems.com

 

[waross]

Buried somewhere in the links is an account of two European pilots who tried the first procedure in a simulator. The simulator that they were using was true enough to demonstrate that the procedure was not possible.

However, a separate analysis done by Bjorn Fehrm, a former jet-fighter pilot and an aeronautical engineer who is now an analyst with Leeham.net, replicates Lemme’s conclusion that excessive forces on the stabilizer trim wheel led the pilots to lose control.

Fehrm collaborated with a Swedish pilot for a major European airline to do a simulator test that recreated the possible conditions in the Ethiopian cockpit.

A chilling video of how that simulator test played out was posted to YouTube and showed exactly the scenario envisaged in the analysis, elevating it from plausible theory to demonstrated possibility.The Swedish pilot is a 737 flight instructor and training captain who hosts a popular YouTube channel called Mentour Pilot, where he communicates the intricate details of flying an airliner. To protect his employment, his name and the name of his airline are not revealed, but he is very clearly an expert 737 pilot.

In the test, the two European pilots in the 737 simulator set up a situation reflecting what happens when the pre-software fix MCAS is activated: They moved the stabilizer to push the nose down. They set the indicators to show disagreement over the air speed and followed normal procedures to address that, which increases airspeed.

They then followed the instructions Boeing recommended and, as airspeed increases, the forces on the control column and on the stabilizer wheel become increasingly strong.After just a few minutes, with the plane still nose down, the Swedish 737 training pilot is exerting all his might to hold the control column, locking his upper arms around it. Meanwhile, on his right, the first officer tries vainly to turn the stabilizer wheel, barely able to budge it by the end.

If this had been a real flight, these two very competent 737 pilots would have been all but lost.

Someone has a simulator good enough.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[MDEAus]

To use an analogy of working the hand wheel to trim the aircraft under high loads. Big game fisherman do a similar thing, it is far easier to use both hands to pull on the rod and then as they drop the tip quickly wind any slack up then use both hands to pull on the rod again.

Alistair what do you think of the 18 odd degrees pitch during rotation? Isn't that high for a 737? The sudden drop in pitch after lift off doesn't seem right to me either(drops to roughly 8.8 in less than 3 seconds approx 3 degrees/second change of pitch).

 

[LionelHutz]

SparWeb - Any data I have seen says the cutout switches disable electrical operation of the stabilizer trim actuator/jack screw. Yet the report shows that the trim actuator/jack screw moved electrically right before the crash. 2 small nose up movements from pilot input and a big automatic nose down movement (presumably MCAS). It's rather hard to reconcile these movements unless the pilots had moved the switches again.

 

[saikee119]

I read somewhere about a week or 10 days ago that there is only one 737 Max 8 simulator available with MCAS.

It appears that the manually trimming the plane by the crank wheels, when the plane is out of trim in a nose dive situation, doesn't appear to be a viable solution. The Senate should ask FAA/Boeing to demonstrate how it is done.

 

[moon161]

"I read somewhere about a week or 10 days ago that there is only one 737 Max 8 simulator available with MCAS."

Yes, that was discussed in the thread on the lion air crash.

 

[waross]

In the test, the two European pilots in the 737 simulator set up a situation reflecting what happens when the pre-software fix MCAS is activated

They did not need a Max8 simulator to set up the same conditions that the MCAS caused.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[Alistair_Heaton]

"Alistair what do you think of the 18 odd degrees pitch during rotation? Isn't that high for a 737? The sudden drop in pitch after lift off doesn't seem right to me either(drops to roughly 8.8 in less than 3 seconds approx 3 degrees/second change of pitch)."

18 deg is completely normal in fact less than what I used yesterday with a 22 ton Q400 which was 20 deg. Noise abetment usually means we are required to rotate and then smoothly pitch at 3 deg rate of change until we maintain V2 + 10 knots while the gear comes up. Then at an altitude which we call acceleration we accelerate to V climb and clean the flaps up. We have a company limitation on pitch of 20 degs on the Q400 so at 22 tons I was pitch 20 deg nose up and way beyond V2 +10 more like V2 +50. At 1000ft acceleration I would pitch down to get V climb to approximately 10 deg then accelerate to V climb then pitch up again. Then at 3000ft accelerate to 210 knots which we then hold to 10 000ft and then go into a pitch hold mode at 5 deg pitch attitude all the way up to FL250 ( this is a slightly strange procedure normally you would not climb an aircraft in anything other than airspeed hold mode but the q is a bit different and if we did that at book speeds the hosties wouldn't be able to get the carts up the cabin as it would be at 10 deg most of the way up, you never see the low speed warning tape on the speed tape so there is no chance of stalling).

I have tried it in the sim and to keep V2+10 in a 22 ton Q, needs just under 30 deg nose pitch attitude which would scare the hell out of the punters plus also it gives us a rather sporty level off at 4000 ft when you going up at 4500ft per min.

At 29.5tons the Q needs 15 deg nose pitch to maintain V2+10.
Speeds for the Q 22tons and (29.5 tons)

V1/Vr 113knts (133)

V2 117nts (135)

Vflup 126 knts (145)

V climb 137 knts. (157)

 

[LittleInch]

Everytime I look at the current report things don't line up as we all suspect they should.

For instance, it is pretty clear from the recording and the data that after manually inputting trim ANU (but for some reason only back to 2.3 units and not the original 5) they managed to throw one or both Stab trim cut out switches. There is then a single automatic trim down, presumably from the MCAS which now does nothing. Then nothing from the auto system calling for AND despite the AOA sensor still wildly out of control and the stick shaker going off indicating the system thinks there is an incipient stall about to happen.

Then when they apparently re-activate the electric trim it comes back into play again. How did it (MCAS) know?

I would assume in the 737NG if the AOA indicator goes beserk then this would instigate all sorts of alarms and stick shaking etc as it would use this as a key input into the stall warning? Or is the stall warning cleverer than that and needs other inputs?

How does the NG cope with incorrect AOA signals?

I feel a lot for the captain having very dodgy data and a continuous stick shaker. I'm no pilot but from what I've seen and read this (stick shaker) not only makes a fairly loud noise but is like hanging onto a pneumatic jack hammer which you can't turn off and you can't let go of.

I'm struggling to see how Boeing are going to get around not having to have an MCAS cut out switch to allow all the other aspects of the aircraft stay the same as before. Trying to modify the software wouldn't cut it for me. when software gets very odd readings it tends to do strange things never envisaged so the only way to eliminate it as a risk is to provide a switch or button of some sort, to add of course to the multitude of buttons already there...

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.