On the recent two crashes of Boeings 737 Max

[Rockin Robbins]

Originally Posted by Dowly

The stroking of the pointy end of the Boeing in this thread is astounding.

Dowly, when someone can't contest the evidence, and all I've done is follow the evidence trail of the actual Preliminary Accident Report, and reported without bias what I found there, and what Juan Brown, blancolirio of You Tube, commercial pilot for 30 years, presently flying 777s loaded with passengers has to say, then they merely admit I'm right by making up a colorful catch phrase like yours above. However, several facts are crystal clear.

* Boeing was absolutely clear and complete in its communication with Ethiopian Airlines, alerting them that the trim overrun situation in the Lion Air crash was definitely a trim overrun situation and probably an error involving MCAS and a jammed angle of attack sensor. Boeing required the addition of a page to the Aircraft Operations Manual an requested that the 737 Operations Manager of Ethiopian Airlines brief all pilots on the possibility, emphasizing that this is merely a variation of the trim overrun memory procedure in place for the past 52 years.

* The pilot followed the memory procedure for switching the elevator trim cutout switches to "cutout," which kept MCAS from executing any more actual trim changes to the airplane. The data flight recorders confirmed that the cutout switches were in the correct position, by recording MCAS commands to enter down trim that could not be applied because the electric trim switches were turned off.

*The flight recorder shows that the pilots neglected to fly the airplane by reducing throttle (airspeed steadily increased to 500 knots, twice the Vmo for the 737 Max at under 10,000 feet. No competent pilot would have allowed the plane to exceed even 300 knots. Because of neglect of rudimentary flying skills, this plane exceeded 500 knots. Indeed, overspeed alarms at high volume were sounding throughout the entire last half of this 10 minute flight. The throttles were never touched.

* Trim controls were unable to be manually adjusted due to the extreme overspeed condition of the plane, putting extreme aerodynamic loads on the elevator trim screw and manual trim system. The plane was literally in danger of coming apart before it even hit the ground.

* Unable to trim the plane, but clearly in control of altitude, according to the altitude plot, the pilot decided the proper thing to do was to "put the terrorist back in control of the aircraft" (my words). Ironically, he could actually have done this safely and I'll detail how.

First, fly the friggin' airplane. First thing you learn in flight school before you crawl into that Cessna 172 is "Aviate, navigate, communicate" in that order. First keep the plane in the air, then figure out where you are with a now stable airplane, then communicate with crew and ground to decide what to do next. These guys forgot to fly the plane. First thing they should have done, since they were in generally level flight is to divide jobs. Pilot works the controls and only does that. Co-pilot throws switches, debugs the problems and communicates. This isn't my idea. It's 100 year old established and time tested emergency procedure, known to every flight crew on the planet.

Pilot should instantly have seen that his speed was threatening to tear the aircraft apart, then asked the co-pilot to reduce throttles to level cruise levels. After several seconds the plane would be flying level at less than 250 knots, unloading the trim system and allowing the copilot to easily trim the elevator. But suppose the trim couldn't be done manually. As the altitude plot clearly shows, the pilot had altitude control! At no point since the cutout switches were engaged had MCAS made the tiniest change to elevator trim and the pilot was climbing using yoke pressure alone! They no longer had an MCAS emergency. They had a gross overspeed emergency and never realized or reacted to it with appropriate actions.

* Leaving the gross overspeed condition to become deadly, the pilot engaged the cutout switches, turning MCAS back on. He did this to be able to try the electric trim switch on the yoke. And it WORKED. He actually was able to trim the plane all the way neutral. He then had five seconds of controlled level flight before MCAS reengaged, and on the basis of the jammed angle of attack sensor moved the trim all the way to full down, crashing the plane.

Although turning the cutout switches back on was totally against Boeing and Ethiopian Airlines procedures, airline captains are like old time ship captains. They are free to elect to ignore procedure in order to save the airplane. Ironically, this could have worked in a strictly controlled manner.

First, the pilot, confining his job to flying the plane manually only would have to lay out the entire plan to his co-pilot. "Here's what we're going to do. I am going to tell you to switch the elevator trim cutout switches to "on" so I can use the electric trim switch. When you do I'll trim the plane neutral. As soon as I release the switch I'll tell you to move both elevator trim cutout switches to "cutout." You only have five seconds to do that before MCAS takes over again and if it does it will give us full down trim. Repeat that back to me." When they both demonstrate full comprehension, the pilot would give the command to reengage the elevator trim cutout switches. He would use the electric trim on his yoke (which turns MCAS temporarily off) to trim to neutral. Immediately he would order "cutout" and the co-pilot would have 5 seconds to throw both switches, an eternity when your life's on the line. It would be against procedure, but it would have worked. I asked Juan if that would work and his reply was "Yes, only if very carefully coordinated."

However that extreme measure wasn't necessary. The pilot had altitude control. All he had to do was reduce throttle, trim straight and level with throttle, assess his altitude and if he needed more, establish throttle settings and attitude for climb to a safe altitude. He then could have again trimmed straight and level throttle and attitude. At that point the elevator would be entirely unloaded, flying at proper airspeed and the co-pilot could have easily manually trimmed to neutral.

This incident, which should have been only a momentary annoyance, was allowed by bad piloting skills, and an unfortunate succession of faulty pilot decisions, to become a life-ending disaster. That's the very definition of pilot error.

Of course if anyone wants to persuade people, providing better facts and better reasoning based on actual aviation experience that I'm wrong, all my statements are falsifiable. But merely proclaiming them to be "The stroking of the pointy end of the Boeing" is just an exercise in informing people that you are unable to dispute what I say.

[Catfish]

Well as far as i read the trimming automatics came on after being put to off position, this video does not mention one word of this.
Not speaking about how you want to build a plane using less fuel while changing aerodynamics and trying to patch this with software.

https://leehamnews.com/2018/11/14/bo...to-the-pilots/
"It’s probably this counterintuitive characteristic, which goes against what has been trained many times in the simulator for unwanted autopilot trim or manual trim runaway, which has confused the pilots of JT610. They learned that holding against the trim stopped the nose down, and then they could take action, like counter-trimming or outright CUTOUT the trim servo. But it didn’t. After a 10 second trim to a 2.5° nose down stabilizer position, the trimming started again despite the Pilots pulling against it. The faulty high AOA signal was still present."

"How should they know that pulling on the Yoke didn’t stop the trim? It was described nowhere; neither in the aircraft’s manual, the AFM, nor in the Pilot’s manual, the FCOM. This has created strong reactions from airlines with the 737 MAX on the flight line and their Pilots. They have learned the NG and the MAX flies the same. They fly them interchangeably during the week.
They do fly the same as long as no fault appears. Then there are differences, and the Pilots should have been informed about the differences."

Not mentioning that if one of two sensors fail let the electronics decide which one to trust and not alarming the pilot.

Despite some omissions he also clearly states that this runaway trim was not able to overcome manually with the trim wheels due to the load on the elevators. But you do not take away thrust in a starting condition at a high angle of attack, when your plane's nose goes up and down without being able to control it, and they had two minutes to check it all. Not enough altitude. They were two pilots, not one of them seems to have realized the speed. I can only imagine howit is with a runaway stabilizer, warnings blaring and then adding another one with overspeed.
https://www.flightglobal.com/news/ar...runawa-453443/
" ... in the case of the Lion Air Boeing 737 MAX crash, “now the airplane is pitching down and actually moving the control wheel will not stop that system. If the pilot uses the trim system on the yoke, the [MCAS] system will stop" but "if the airplane isn’t in the proper attitude it will reactivate, ...”
Two minutes sounds like much time and mybe for a fighter pilot it is, but..

Maybe it was a 'pilot error', or an unlucky combination of changed 737's properties and the pilot(s) (both of them!) knowledge, but in any case it is not a good idea to use several automatic systems fighting each other, and overloading the pilot with figuring it all out and requiring inputs to correct faulty sensors.
I do not like Airbus for exactly this reason. Taking control away from pilots is seldomly a good idea when there is a real problem.

[Rockin Robbins]

Originally Posted by Catfish

Well as far as i read the trimming automatics came on after being put to off position, this video does not mention one word of this.

The words "the pilots repeatedly followed procedures by Boeing and MCAS continued to turn back on" came from the airline, not the Preliminary Accident Report, which says no such thing. Who made up that whopper, of course, is unknown.

Originally Posted by Catfish

https://leehamnews.com/2018/11/14/bo...to-the-pilots/
"It’s probably this counterintuitive characteristic, which goes against what has been trained many times in the simulator for unwanted autopilot trim or manual trim runaway, which has confused the pilots of JT610. They learned that holding against the trim stopped the nose down, and then they could take action, like counter-trimming or outright CUTOUT the trim servo. But it didn’t. After a 10 second trim to a 2.5° nose down stabilizer position, the trimming started again despite the Pilots pulling against it. The faulty high AOA signal was still present."

Again, facts ONLY come from the Preliminary Accident Report, not the malfunctioning news media. Several statements in this so-called news report are completely false. "It’s probably this counterintuitive characteristic, which goes against what has been trained many times in the simulator for unwanted autopilot trim or manual trim runaway, which has confused the pilots of JT610." is entirely wrong. The memory procedure for dealing with trim overrun was written before April of 1967 and has been in continuous use since then. MCAS is only one of several possible causes of routine trim overrun malfunction. This is a routine malfunction to be handled routinely. See the Preliminary Accident Report for complete verification.

Originally Posted by Catfish

"How should they know that pulling on the Yoke didn’t stop the trim? It was described nowhere; neither in the aircraft’s manual, the AFM, nor in the Pilot’s manual, the FCOM. This has created strong reactions from airlines with the 737 MAX on the flight line and their Pilots. They have learned the NG and the MAX flies the same. They fly them interchangeably during the week.
They do fly the same as long as no fault appears. Then there are differences, and the Pilots should have been informed about the differences."

Again for a complete and thorough treatment of MCAS and electric trim behavior see the Flight Operations Manual section of the Preliminary Accident Report. Pilots knew that pulling on the yoke would never influence the trim system in any way. This has been true for 52 years and nobody in three generations has been concerned about that. The trim system memory procedures are identical for all flavors of 737 and are a memory procedure. Prospective pilots must demonstrate that they know from memory, without reference to a manual, how to deal with this problem. It's a routine, straightforward 100% effective way to deal with any electric trim system overrun, no matter how it's caused, by MCAS or any one of dozens of other possibilities. The MAX flies identically and the procedures for trim overrun are identical to all 737 series.

Originally Posted by Catfish

Despite some omissions he also clearly states that this runaway trim was not able to overcome manually with the trim wheels due to the load on the elevators.

They were unable to manually trim the aircraft because they were flying it more than twice the maximum operating velocity of the aircraft, not because MCAS was fighting them.

Originally Posted by Catfish

But you do not take away thrust in a starting condition at a high angle of attack, when your plane's nose goes up and down without being able to control it, and they had two minutes to check it all. Not enough altitude.

They were eight minutes into the flight. Where does two minutes come from. They were at enough altitude that level flight, which they had attained wouldn't result in controlled flight into terrain. Altitude wasn't the emergency.

Originally Posted by Catfish

They were two pilots, not one of them seems to have realized the speed. I can only imagine howit is with a runaway stabilizer, warnings blaring and then adding another one with overspeed.
https://www.flightglobal.com/news/ar...runawa-453443/
" ... in the case of the Lion Air Boeing 737 MAX crash, “now the airplane is pitching down and actually moving the control wheel will not stop that system. If the pilot uses the trim system on the yoke, the [MCAS] system will stop" but "if the airplane isn’t in the proper attitude it will reactivate, ...”

Look at the altitude plot in the Preliminary Accident Report, the ONLY, ONLY source of facts available. At the time the elevator trim override switches were reengaged, the pilot had climbed the airplane to a safe altitude, MCAS was disconnected and unable to influence trim any longer. There WAS NO runaway stabilizer. The co-pilot had saved the airplane. That's when the pilot violated protocol, reengaged the electric trim system and handed control back to MCAS, which he knew would immediately crash the airplane. He put MCAS back in control, regained neutral trim and then let MCAS crash the plane. Pilot error.

"Two minutes sounds like much time and mybe for a fighter pilot it is, but.."[quote] But they had more than 8 minutes to fix it. They did and still found a way to crash the plane.

Originally Posted by Catfish

Maybe it was a 'pilot error', or an unlucky combination of changed 737's properties and the pilot(s) (both of them!) knowledge, but in any case it is not a good idea to use several automatic systems fighting each other, and overloading the pilot with figuring it all out and requiring inputs to correct faulty sensors.
I do not like Airbus for exactly this reason. Taking control away from pilots is seldomly a good idea when there is a real problem.

Several systems were not fighting each other here. Airbus killed more people with a plane that actually malfunctioned, removing control of all functions from the crew, which was left with no possible control of the aircraft.

You're totally correct. New emphasis in manual control of aircraft, proper instrument scan routines, seat of the pants flying needs to be done, especially in third world countries. Total dependence on automatic systems is sure death. This incident totally proves that, but the total dependence doesn't reflect on Boeing, it reflects on the airlines, probably even American airlines, and the individual pilots who don't seek to actually know how to fly. They merely monitor automatic systems and watch the crash from especially close up when the automatic systems fail. And they WILL fail sometimes.

[Catfish]

^ it would appear the evidence we have points to that you are right, and the crucial action that did not take place was switching the throttles to manual to lower the speed and have less pressure on the elevator controls.



When the Aoa vane or some data transfer on one side was indeed damaged why did the MCAS system take this input for real, when there was the second one working?
The vane or some part of the one Aoa sensor on one side is damaged, the control system gets strange readings and sops, handing control to the pilots - autopilot off - ok.

In the second the autopilot is off, the MCAS system counts to 5 seconds and then 'adjusts' the pitch down because of the one wrong one Aoa reading, but what is with the second one?

I still wonder why (and if?) they really engaged the auto trim again when they had regained level flight, if being too fast. Or if it can have been a system fault(?) There also seem to be a lot of Aoa indicators failing recently

[mapuc]

When it comes to fly or to fully understand how to fly an airliner, like a 747 or similar, I'm useless.

I do know, however that these air crash detectives are really, really good at what they are doing.

In the nearest future we will know exactly what happened and what caused it.

Maybe the producere will upgrade some software and/or some hardware and the pilots will have to upgrade some learning on take-off.

Markus

[Skybird]

Originally Posted by mapuc

When it comes to fly or to fully understand how to fly an airliner, like a 747 or similar, I'm useless.

I do know, however that these air crash detectives are really, really good at what they are doing.

In the nearest future we will know exactly what happened and what caused it.

Maybe the producere will upgrade some software and/or some hardware and the pilots will have to upgrade some learning on take-off.

Markus

They do upgrade the software, but the patch had to be pulled again because it was bad, too. MCAS trim is nothing new, it is around since a very long time, but the 737 Max has so drastically changed airframe geometry and shifts in the weight distribution due to the heavy engines moving forward, that parts of the code had to be written new to match the new airframe. The plane is now more vulnerable to the tail striking the runway during takeoff, becasue the gear has moved forward together with the wings, and so the tial got longer. These changes in MCAS trim are suspected to not being documented sufficiently in order to save time and get the airplane out earlier - because if new training beyond a certain treshhold level is required for a pilot who switches to another but "familiar" plane model, the FAA demands a new certification process for the plane itself, and the procedures for that cost much more time than the way the pushed it through the process now: becasue a pilot who flies lets say a 737-600 or -700, mostly is qualified to also fly the -800 and -900 models, since they are quite similiar. If training and documentation beyond a certain amount would be required, FAA ticks by the logicof that then the plane is quite so different from earlier versions of the family that a new certification of the hardware is necessary - and that is what Boeing wanted to avoid, since they lost orders on Airbus' 320 and a further certification of the hardware would have costed them more time.

If then the new part of the code maybe was programmed with an error or several ones in it, or the code commands a handling that is too different than what the pilot knows from earlier versions of the plane, but Boeing did skip proper documentaiton and training (a claim that has been risen by many pilots by now from several airlines areound the globe), then you get into very serious problems. The software issue obviously is serious - a patch Boeing had announced for the MCAS trim thing, had to be pulled again and given back into rework once again. It does not matter whether there is really a flaw, or the work ergoniomic demanded by the new software collides with the pilots' handling as he knwos MCAS - the way it functions has to be recoded, obviously. That Boeing engineer said that normally for developing a project like the 737 MAx and its changes over earlier versions of the 737 (which already are quite optimised to ther max and thus do not offer too much space for more cost efficienct operation anymore, Boeing would have given them m ore than twice the time than they had this time, indicates that the race with airbus was a priority. And that was bad, they overplayed it apparently. Lacking docuemntation. Lacking communication. Lacking retraining to avoid new certification. Lacking knowledge on side of the pilots who did not - and could not!! - have fully understood the changes. Boom. Boom.



Additionally the FAA has grounded the plane model for another software error unrelated to the MCAS issue, that the FAA rates serious enough that for that new issue alone they keep the plane grounded. Boeing, of course, says its minor. What else should they say - they have lost two planes and 300 people are killed and their PR currently hits rock bottom. The new issue illustrates that deliverign new software with errors in it, is not only possible, but real. The enormous time pressure that a Boeing engineer has pointed out in the project and the desire to avoid certification procedures bvy the FAA to save more time, certainly did not help to run all tests properly and check things the way they usually do.

If adding all these hints together, its cheap to already label it a pilot error just to give Boeing a stain-free, clean jacket again. Its far more likely that Boeing pushed the pressure level beyond their usual safety limits. You cannot avoid to add that conclusion to the list of possebilities. Ethiopian Airlines must have had a reason why they did not deliver the blackbox to the US and Boeing for analysis, but to France. depending on whom you ask, that is more or less an affront. Boeing was said to be not happy with that decision and wanted the state department to intervenbe and set up diplomatic pressure on France. Trump was wise enough not to allow that, since the French - the initiators and in principal the founders of Airbus - certainly would have turned stubborn. US diplomacy could only lose, and the criticism that Boeing is being too close to the US goverment and the Pentagon would have gotten fed for free - and this after Boeing was just found guilty by the WTO to have gotten illegal state subventions, like Airbus before. No, staying out of this was the best Trump could have done.

[Rockin Robbins]

Skybird, what are you trying to imply?

Ethiopian Airlines must have had a reason why they did not deliver the blackbox to the US and Boeing for analysis, but to France. depending on whom you ask, that is more or less an affront. Boeing was said to be not happy with that decision and wanted the state department to intervenbe and set up diplomatic pressure on France.

Ethiopian Airlines had nothing to do with where the black boxes were read. That was determined by the local air traffic safety authority. Boeing and the FAA were present when the boxes were read. They were given the full contents of the instruments. Implying that they wished to obtain the black boxes so they could redact unfavorable data is not only wrong, it's reprehensible. And as you can plainly see, the data as extracted in France exculpates Boeing. Shame on you.

The plane is now more vulnerable to the tail striking the runway during takeoff, becasue the gear has moved forward together with the wings, and so the tial got longer.

This characteristic is shared by dozens and dozens of commercial cargo and passenger planes from all manufacturers and nation. It's nothing remarkable and you're implying that it paints Boeing with some kind of rash irresponsibility. Bullocks.

If training and documentation beyond a certain amount would be required, FAA ticks by the logicof that then the plane is quite so different from earlier versions of the family that a new certification of the hardware is necessary - and that is what Boeing wanted to avoid

And that's entirely right and proper. After all, every 737 for the past 52 years could have an electric trim overrun, MCAS is just a new reason that might happen. If you have a trim overrun in a 50 year old version or a Max version, procedures are identical. Many trim overruns have happened over the years. Many pilots have reacted properly turning an annoyance into a harmless event rather than a tragic crash. MCAS trim overruns are not different in character or remedy than any trim overrun that has ever happened in thousands of aircraft over 52 years, and with three generations of pilots and crew. The plane is safe. And it can be made safer, just like any other plane.

Lacking knowledge on side of the pilots who did not - and could not!! - have fully understood the changes. Boom. Boom.

The pilots didn't need to know the changes. They already knew from memory the steps needed to fix a trim overrun. This was nothing new. It was a routine failure that should have been handled routinely. It wasn't.

Procedure says to shut down electric trim by turning the elevator trim override switches to "override." The co-pilot did this, showing that they knew the procedure. The pilot, with an out of trim plane, hand flew the plane to a save altitude and leveled off while his 94% throttle accelerated the plane like a dragster to twice its rated speed for that altitude.

They didn't have a trim problem then. They had an airplane that was about to be disassembled by aerodynamic forces! Still neither touched the throttles until impact. Note that planes at twice safe speed limits (250 knots for 10,000 feet or below) respond quickly and violently to trim inputs. Since the pilot had control of the altitude and indeed doubled the altitude while he was hand controlling the plane, the proper thing for him to do was FLY THE PLANE!

Instead, he turned a known malfunctioning system back on so it could kill everybody. Memory procedure, 52 years old, says clearly to leave the trim override switches off for the remainder of the flight. This pilot did not. Somehow this is Boeing's fault.


Boeing exhibit A, from the ONLY source of facts we have, the Preliminary Accident Report:

IssueDate: November 6, 2018
Airplane Effectivity: 737-8 /-9
Subject: Uncommanded Nose Down Stabilizer Trim Due to Erroneous Angle of
Attack (AOA) During Manual Flight Only
Reason: To Emphasize the Procedures Provided in the Runaway Stabilizer Non-
Normal Checklist (NNC).
Information in this bulletin is recommended by The Boeing Company, but may not be FAA approred
In the event of conflict with the FAA approved Airplane Flight Mammal
(AFM) the AFM shall supercede. The Boeing Company regards this information or procedures described herein as having a direct or indirect bearing on the safe operation of this model airplane.

THE FOLLOWING PROCEDURE AND/OR INFORMATION 1S EFFECTIVE UPON RECEIPT
Background Information
The Indonesian National Transportation Safety Committee has indicated that
Lion Air flight 610 experienced erroneous AOA data. Boeing would like to call
attention to an AOA failure condition that can occur during manual flight only.
This bulletin directs flight crews to existing procedures to address this condition.
In the event of erroneous AOA data, the pitch trim system can trim the stabilizer
nose down in increments lasting up to 10 seconds. The nose down stabilizer trim
movement can be stopped and reversed with the use of the electric stabilizer trim
switches but may restart 5 seconds after the electric stabilizer trim switches are
released. Repetitive cycles of uncommanded nose down stabilizer continue to
occur unless the stabilizer trim system is deactivated through use of both STAB
TRIM CUTOUT switches in accordance with the existing procedures in the
Runaway Stabilizer NNC. It is possible for the stabilizer to reach the nose down
limit unless the system inputs are counteracted completely by pilot trim inputsFlight Crew Operations Manual Bulletin No. ETH-13 , Dated November 6, 2018 (continued)
Additionally, pilots are reminded that an erroneous AOA can cause some or all of
the following indications and effects:
» Continuous or intermittent stick shaker on the affected side only.
* Minimum speed bar (red and black) on the affected side only.
» Increasing nose down control forces.
» Inability to engage autopilot.
° Automatic disengagement of autopilot.
» IAS DISAGREE alert.
°. ALT DISAGREE alert.
» AOA DISAGREE alert (if the AOA indicator option is installed)
. FEEL DIFF PRESS light.
Operating Instructions
In the event an uncommanded nose down stabilizer trim is experienced on the
737-8 /-9, in conjunction with one or more of the above indications or effects, do
the Runaway Stabilizer NNC ensuring that the STAB TRIM CUTOUT switches
are set to CUTOUT and stay in the CUTOUT position for the remainder of the
flight.
Note: Initially, higher control forces may be needed to overcome any
stabilizer nose down trim already applied. Electric stabilizer trim can
be used to neutralize control column pitch forces before moving the
STAB TRIM CUTOUT switches to CUTOUT. Manual stabilizer trim
can be used after the STAB TRIM CUTOUT switches are moved to
CUTOUT.Administrative Information
Insert this bulletin behind the Bulletin Record page in Volume 1 of your Flight
Crew Operations Manual (FCOM). Amend the FCOM Bulletin Record page to
show bulletin ETH-12 "In Effect" (IE).
This Bulletin remains in effect until Boeing provides additional information on
system updates that may allow this Bulletin to be canceled.
Please send all correspondence regarding Flight Crew Operations Manual
Bulletin status, to the 737 Manager, Flight Technical Data, through the Service
Requests Application (SR App) on the MyBoeingFleet.com

Folks, that's not a company attempting to hide potential harm from its customers. It is a company going the extra mile, even without FAA approval, to fully inform its customers, giving them a complete view of the possible malfunction and a 100% effective method to respond to it. This is a textbook example of a company putting the safety of its customers ahead of everything else, being transparent, helpful and open.

But Skybird paints them evil shirkers of responsibility, actively hiding known defects in their planes because dead people buy the most airplanes. That position is not possible given the facts revealed in the Preliminary Accident Report. But undeterred, Skybird says what he says, although completely contradicted by the truth.

A third passenger pilot/engineer in the blancolirio discussion said this after reading my analysis: "@RockinRobbins13 This guy gets it" On a subsequent post he clearly states "Rob Roilen
5 days ago
@RockinRobbins13 Agreed. I see a lot of people regurgitating the latest half-true mainstream media updates and calling for software fixes without addressing some really common sense flying practices that simply were not used in this accident. Sure, refine MCAS, but teach pilots to rely less on automation." All three commercial pilots and engineers agreed with my assessment that the Ethiopian Airlines crash was caused by pilot error. Doesn't make it any less tragic but facts are stubborn things.

I would be happy to conduct a line by line review of the Preliminary Accident Report for those who doubt I am telling the simple unbiased truth. But please read it for yourself, very carefully, before disagreeing with my conclusions. It will prevent a lot of embarrassment.

[Buddahaid]

Originally Posted by Catfish

When the Aoa vane or some data transfer on one side was indeed damaged why did the MCAS system take this input for real, when there was the second one working?
The vane or some part of the one Aoa sensor on one side is damaged, the control system gets strange readings and sops, handing control to the pilots - autopilot off - ok.

In the second the autopilot is off, the MCAS system counts to 5 seconds and then 'adjusts' the pitch down because of the one wrong one Aoa reading, but what is with the second one?

That's the part where Boeing offered a reduced price MCAS system that used only one AOA sensor at a time selected by the PIC. The MCAS system that optionally used both AOA sensors and alerted the crew when they didn't agree is what Boeing is now installing at no charge and treating as standard equipment now. The PIC should have recognized the AOA sensor he was using was giving erratic readings and switched to the other sensor.

One might make a similar argument that if you back over a kid on a tricycle in your car, and didn't buy the back up camera with a proximity sensor, that it's the auto manufacturers fault for not making the equipment standard in the first place.

[Rockin Robbins]

Originally Posted by Buddahaid

One might make a similar argument that if you back over a kid on a tricycle in your car, and didn't buy the back up camera with a proximity sensor, that it's the auto manufacturers fault for not making the equipment standard in the first place.

And that perfectly illustrates why safety features don't appear. Manufacturers can't offer them as options because, having the most money in the transaction, if the driver gets it and doesn't turn it on, that's the manufacturer's fault. If the customer doesn't buy the option, then that's the manufacturer's fault. If the driver has a fully functioning backup camera and backs over the tricycle anyway, that's also the manufacturer's fault. It keeps safety equipment from being deployed because of the misuse of the legal system as a lottery with much better odds.

These manufacturers are not our enemy. They make possible the things we enjoy in life. Vendettas to put them out of business are much more dangerous than the real or imagined faults they pretend to remedy.

[Dowly]

Originally Posted by Rockin Robbins

*The flight recorder shows that the pilots neglected to fly the airplane by reducing throttle (airspeed steadily increased to 500 knots, twice the Vmo for the 737 Max at under 10,000 feet. No competent pilot would have allowed the plane to exceed even 300 knots. Because of neglect of rudimentary flying skills, this plane exceeded 500 knots. Indeed, overspeed alarms at high volume were sounding throughout the entire last half of this 10 minute flight. The throttles were never touched.

Can you point where, during the time the pilots had control of the plane, did they exceed 500 kts?




Also, if you watched the video I posted above, you see that in a simulator at 300kts it takes some force to move the manual trim and at 340kts it becomes extremely hard to use the manual trim.


Seen as the video has been deleted from vimeo, here is a transcript:

C: We have an IAS disagree.
C: So, IAS disagree memory items.
F: Autopilot if engaged, disengage.
C: Disengaged!
F: Autothrottle if engaged, disengage.
C: Disengaged!
F: Flight directors - Both up
F: With flaps up established a flight path 4 degrees and 75% N1.
C: So, 75% N1.
F: We have 77, 76,...
C: A little bit less...
F: And, there you go.
C: 4 degrees.
F: 4 degrees.

C: So I am trying to establish this now.
F: Check!
F: We are descending...?
F: We probably... Are you feeling troubled with...
F :Any trouble with the flight control?
C: Yeah, I'm trying to trim it but...
C: It continues to trim against me when I'm trimming
C: So state the malfunction, please.
F: Yeah, this doesn't look right. Looks like uh...
F: How do you feel the stabilizer, the trim system?
F: Can you control it?
C: I'm trimming it. It is responding but...
F: It's a runaway stabilizer, if you agree?
C: For every time that I trim backward, it keeps trimming forward.
F: It's trimming forward. Yeah, it's runaway stabilizer.
C: So, runaway stabilizer memory items...
C: And i'm trying to keep this thing at 4 degrees.
F: Control column, hold firmly.
C: I am... [CAPT is holding the yoke firmly with both hands]
F: Autopilot - if engaged, disengage.
C: It's disengaged.
F: Autothrottle - if engaged, disengage.
C: It's..., if you can disengage it for me, make sure that it's disengaged.
F: It's disengaged.
F: And, do you feel that the failure stop?
F: Negative?
C: No, it's still moving.
F: Stab trim cutoff switches to cutoff.
F: OK. It stops. It looks like it stops.
C: You can see now I'm using almost full back pressure here.
F: Exactly.
C: How many degrees nose down?
F: We have 4 units nose down now
C: 4 units nose down?
F: Yup.
C: OK, I'm struggling.
C: I'm actually using almost my full force to keep the aircraft level here.
F: Do you want me to help you?
C: What I would like to do.
C: Just for the sake of exercise, can you trim this forward? [to simulate MCAS trim AND]
C: See if we can reach even zero nose down.
C: And see if I can even hold it.

[FO is trying to crank the trim wheel to reach zero nose down, simulating MCAS AND]

C: So, now we are doing this just as an exercise!
C: Do not try this at home.
C: This...
C: We are at 300 knots now.
F: I'm fighting.
C: I'm sttrugling to to keep this aircraft flying.
F: My god! [FO surprised at how hard it is to trim further nose down]
C: Yeah, the thing is with higher speed the force on the stabilizer will be higher and higher as well.
C: So it becomes almost impossible to move it.
C: So we are now at about 3 degrees.
F: Yup. [FO still tries to continue trimming nose down, the wheels is so difficult to spin]
C: We're still about 3 degrees away from full nose down trim.
C: And I am using everything that I have. [CAPT still holding on to his yoke with both hands]
F: My God ! [the trim wheel barely move for the down trim]
C: This is realistic guys.
C: This is how much of effort it would take to trim the stabilizer at this kind of speed.
C: Umph... [Capt is still trying to hold on to his yoke with his hands]
C: I'm just in control of it, though. But it's getting harder and harder.
C: And remember we're still 2.5 degrees away...
F: My God! [FO still struggles to spin the refused-to-be-spun trim wheel]
C: It's not possible, is it?
C: All right, we stop at that.

C: The reason that we have to try...
C: The reason we have to trim this manually is because the normal trim system wouldn't do this, OK.
C: It would require manual trim to get it away from this.
C: That's fine.
C: Trim it backward. [This time to illustrate the effort to trim the nose back up after "MCAS" brought the AC further nose down]
C: Trim it backward as you can.
F: Oh my God! I couldn't... [FO can't spin the wheel to trim up]
C: OK.
C: Eh...
C: Juan, press the red button! [CAPT called the sim operator...]
C: Press the red button now. [to stop the sim session]
C: This is at 340 knots.
C: And the trim is at...It's still at almost 2.5 degrees.
F: Yeah, 2.5 degrees.

What the transcript doesn't convey is that Mentour Pilot has to basically hug the yoke to keep it in control below 340kts and with not as much AND trim as the Ethiopian flight had.

[Rockin Robbins]

Originally Posted by Dowly

Can you point where, during the time the pilots had control of the plane, did they exceed 500 kts?

Dowly, when we're talking about airspeed, you can see (airspeed is the bottom red/blue line, one for each airspeed sensor) the last half of the flight was over Vmo for any altitude. Maximum operating airspeed for under 10,000 feet is 250 knots and the plane was over 300 for that entire time, gaining a 500 knot speed by time of impact, according to the graph from the Preliminary Accident Report. The differences in the speeds supplied by the two sensors reflects the badly out of trim state of the aircraft. Here's a better view of that graph: https://ibb.co/DwpPG45

And a transcript from a simulator session is basically irrelevant to the actual Ethiopian Airlines flight. 340 knots is already 90 knots over maximum flying speed for that altitude, OF COURSE trims are very difficult or even impossible to adjust. The plane was not designed to fly in extreme overspeed conditions. Mentour Pilot proved that, didn't he. Now reflect an additional 160 knots airspeed over the speed where Mentour Pilot couldn't adjust trim and reflect on the consequences of letting the plane get that far outside its rated flight envelope.

However, Mentour Pilot has withdrawn the video of his own volition because "it's wrong." No simulator session can say anything about the facts of what happened on that flight. The final accident report has not been issued and he acknowledged that publishing a "best guess" simulator run with conditions different from the actual flight was wrong and would result in people responding inappropriately to a video that was wrong to produce to begin with. "You subscribe to my channel because you want the facts." The deleted video was pure speculation based on a simulator set up with parameters not reflected in the facts of the case. Mentour Pilot made the right choice for the right reason. Your laborious typing of the transcript from that purely speculative video accomplished nothing at all toward evidence that the pilots don't bear the vast majority of the responsibility for the crash.

Like Mentour Pilot said in his deleted video, "don't try this at home, folks." It's really way beyond any reasonable flying of the aircraft, and not because of MCAS either. Rule #1: fly the plane. Rule #2: see rule #1. These pilots didn't fly the plane. In fact they turned control over, against Flight Manual instructions, to a known malfunctioning electric trim system. Had they followed procedures, they might have saved the flight.

[Dowly]

Originally Posted by Rockin Robbins

Dowly, when we're talking about airspeed, it's not a great idea to show the altitude plot.

It shows the speed graph, look harder. You can also click it to get a bigger picture. MAGIC!

And a transcript from a simulator session is basically irrelevant to the actual Ethiopian Airlines flight. 340 knots is already 90 knots over maximum flying speed for that altitude, OF COURSE trims are very difficult or even impossible to adjust. The plane was not designed to fly in extreme overspeed conditions. Mentour Pilot proved that, didn't he. Now reflect an additional 160 knots airspeed over the speed where Mentour Pilot couldn't adjust trim and reflect on the consequences of letting the plane get that far outside its rated flight envelope.

The VMO of a 737MAX is 340kts, I think? Sorry, that's over 10,000ft. Is that ASL?


EDIT: I can upload and link you the video, Rockin Robbins if you wish.


EDIT2:

[Catfish]

^ @RR im still with you.
They follow the instructions in this vid, however when the AP is switched off due to wrong IAS the MCAS gets active (within 5 seconds ok), so the pilot tries to hold the plane against the MCAS downtrim which gets worse, then realising there is a runaway trim fail he also switches off auto throttle.

So in the above sim video he put auto throttle to manual at 1:27, but he did not throttle back much or so it seems?
So you say this is why they are unable to trim the plane manually because of the forces on the elevator wuth the plane getting too fast, ok.

So what is the reason they did not throttle back more in the above video?
I mean is there any reasonable explanation when three different experienced pilots in videos do not throttle back in this situation, like the ethiopian pilot did (not)?

edit what i do not understand is why he at first lets the copilot trim the plane forward instead of backward, the latter woulod be bringing them out of the situation?

[Dowly]

Originally Posted by Catfish

I mean is there any reasonable explanation when three different experienced pilots in videos do not throttle back in this situation, like the ethiopian pilot did (not)?

You have a AND (=Aircraft Nose Down) trim, reducing power would make it worse which in turn would make the pilot in charge to have to pull back on the yoke even more. The video also does not show all the other crap the Ethiopian pilots had to deal with. Crap like yoke shaker (stall), over speed warning etc. Contradictory warnings.


Also, to address what RR said elsewhere about MCAS not being a band aid; it absolutely is. The MAX wouldn't have gotten certification without MCAS.


EDIT:

edit what i do not understand is why he at first lets the copilot trim the plane forward instead of backward, the latter woulod be bringing them out of the situation?

@2:09 They start to simulate MCAS pulling the nose down. Mentour Pilot is a 737NG pilot, so the simulator is probably also a 737NG one.
EDIT2: To further elaborate; the first downward trim is a run away stabilisator, the manual trim is to simulate the MCAS behaviour.
Unfortunately I've not the full video.

[Rockin Robbins]

Originally Posted by Dowly

You have a AND (=Aircraft Nose Down) trim, reducing power would make it worse which in turn would make the pilot in charge to have to pull back on the yoke even more. The video also does not show all the other crap the Ethiopian pilots had to deal with. Crap like yoke shaker (stall), over speed warning etc. Contradictory warnings.

With nose trimmed down the plane accelerates from gravity. The proper thing to do is reduce throttle to keep speeds from destroying the airframe.

Originally Posted by Dowly

Also, to address what RR said elsewhere about MCAS not being a band aid; it absolutely is. The MAX wouldn't have gotten certification without MCAS.

Absolutely false. In fact, Mentour Pilot says that pilots have flown the 737 MAX with MCAS turned completely off and had difficulty distinguishing the difference. It seems that MCAS, meant to make subtle differences in handling to produce a duplicate of the feel of other 737s was overpowered, but it's a catch 22 situation. Remove the pilot and the automation crashes the plane. Remove the automation and the pilot crashes the plane. In both situations, zealots with rabies pursue Boeing with sharp instruments aiming to dismember them. Perhaps we need to simply outlaw all forms of air transport.

Originally Posted by Dowly

EDIT:@2:09 They start to simulate MCAS pulling the nose down. Mentour Pilot is a 737NG pilot, so the simulator is probably also a 737NG one.
EDIT2: To further elaborate; the first downward trim is a run away stabilisator, the manual trim is to simulate the MCAS behaviour.
Unfortunately I've not the full video.

You mean the video that Mentour Pilot pulled because it was wrong, morally and factually? Yes, that one. As Mentour Pilot said explicitly, the video was in error. it was wrong, it was baseless speculation in the face of facts in contradiction.

But far from the situation of a "crippled plane" that "couldn't fly without MCAS" it appears our real situation is quite different: an MCAS system meant to intruduce subtle changes to the feel of the aircraft, perfectly able to fly safely without it, but MCAS being far more powerful then it needs to be. What kind of scenario is it when MCAS gives full down elevator trim to achieve a similar feel to other 737s. That makesanosensa at all. MCAS should shake the stick to alert the pilots and that's about it. Maybe two units of down trim maximum, with an electric trim button contradicting the MCAS adjustment turning MCAS completely off for the rest of the flight.

Remember: the only facts we have are in the preliminary accident report. You Tube videos, simulator runs, anything not directly dependent on that preliminary accident report are speculation only and have no force of reality.

I predict that MCAS will have its fangs pulled, pilots all over the world will be called upon to evaluate the flying characteristics of the 737 Max and this plane will have a long, respected and safe rest of production for many years.