This is a very salient comment by a former NTSB investigator, and speaks to the amount of information we currently have (silk almost none) as well as the ongoing repeating, reprocessing and sensationalizing of that limited info by the media;
Posted by
Greg Feith
“Although the “theory mill” continues to churn out cause(s) of both the LionAir and Ethiopian B737 MAX accidents, there are several things that should be of concern to the aviation industry and the public regarding the accident investigation activities that are being conducted. Currently, ALL of the facts, conditions and circumstances have not been fully developed and/or properly interpreted at this time in either investigation. Factual information has been slow in coming from either investigative authority (which is their prerogative to determine when, where and how the information will be released), but withholding information from organizations (NTSB,FAA, and Boeing) that have a time-critical need to know is a disservice to the industry and flying public. The fact that the Indonesian investigative authority has substantial data from the CVR and FDR and is currently “cherry picking” the facts they release is somewhat telling. This is exemplified by the fact that newly reported information apparently from the CVR that indicates a “Pilot who hitched a ride saved Lion Air 737 a day before deadly crash” is being perceived as a badge of honor for Lion Air because one of their own pilot’s “saved the day.” However, the disturbing reality is that it took a pilot who was not in command of the flight, and just an observer, to tell the Captain and First Officer (who were supposedly trained, qualified, and experienced in the operation of the Boeing 737 MAX) what the issue was that resulted in the nose of the airplane pitching down (uncommanded pitch trim input also known as a “runway trim”). The fact that the pilots who were in command of the flight and had access to the flight controls did not recognize nor properly respond to the “runaway trim” event is a testament of a more systemic problem within Lion Air. Although MCAS was not in any airline or airline pilot’s vocabulary at that time of the accident, the nose-down event was properly diagnosed and the requisite procedures implement because the dead-heading pilot apparently relied on possibly his training, experience or a combination of both to recognize the event as a runaway trim and coach the pilots through the proper procedures. The flightcrews’ failure to understand the issue and implement the proper corrective actions (which are memory items) is a symptom of a more serious problem and a likely explanation for the loss of the airplane if the accident crew reacted in the same manner - confused, panicked and hoping to find the answer in book rather than reverting to what they would have learned in training.
It is also of interest that it took the Ethiopian investigative team 5 days to find a place to have the FDR and CVR data downloaded and converted to a medium that could be used by investigators to determine the initiating event that lead the pilots to lose control of the airplane. As an investigator, it is hard to understand the logic behind withholding safety-of-flight information, given the fact that the Ethiopian investigators have now had the FDR and CVR data for several days, and nothing has been released other than a generic statement that “the data is similar to that of Lion Air.” The skeptical investigator in me says that if the flightcrew did not have some significant involvement in the loss of the airplane, the Ethiopian investigators would have released the information immediately and singing their praises. I know I am going to get hammered for making a statement like that, but in truth, I hope I am wrong.”
Posted by
Greg Feith
“Although the “theory mill” continues to churn out cause(s) of both the LionAir and Ethiopian B737 MAX accidents, there are several things that should be of concern to the aviation industry and the public regarding the accident investigation activities that are being conducted. Currently, ALL of the facts, conditions and circumstances have not been fully developed and/or properly interpreted at this time in either investigation. Factual information has been slow in coming from either investigative authority (which is their prerogative to determine when, where and how the information will be released), but withholding information from organizations (NTSB,FAA, and Boeing) that have a time-critical need to know is a disservice to the industry and flying public. The fact that the Indonesian investigative authority has substantial data from the CVR and FDR and is currently “cherry picking” the facts they release is somewhat telling. This is exemplified by the fact that newly reported information apparently from the CVR that indicates a “Pilot who hitched a ride saved Lion Air 737 a day before deadly crash” is being perceived as a badge of honor for Lion Air because one of their own pilot’s “saved the day.” However, the disturbing reality is that it took a pilot who was not in command of the flight, and just an observer, to tell the Captain and First Officer (who were supposedly trained, qualified, and experienced in the operation of the Boeing 737 MAX) what the issue was that resulted in the nose of the airplane pitching down (uncommanded pitch trim input also known as a “runway trim”). The fact that the pilots who were in command of the flight and had access to the flight controls did not recognize nor properly respond to the “runaway trim” event is a testament of a more systemic problem within Lion Air. Although MCAS was not in any airline or airline pilot’s vocabulary at that time of the accident, the nose-down event was properly diagnosed and the requisite procedures implement because the dead-heading pilot apparently relied on possibly his training, experience or a combination of both to recognize the event as a runaway trim and coach the pilots through the proper procedures. The flightcrews’ failure to understand the issue and implement the proper corrective actions (which are memory items) is a symptom of a more serious problem and a likely explanation for the loss of the airplane if the accident crew reacted in the same manner - confused, panicked and hoping to find the answer in book rather than reverting to what they would have learned in training.
It is also of interest that it took the Ethiopian investigative team 5 days to find a place to have the FDR and CVR data downloaded and converted to a medium that could be used by investigators to determine the initiating event that lead the pilots to lose control of the airplane. As an investigator, it is hard to understand the logic behind withholding safety-of-flight information, given the fact that the Ethiopian investigators have now had the FDR and CVR data for several days, and nothing has been released other than a generic statement that “the data is similar to that of Lion Air.” The skeptical investigator in me says that if the flightcrew did not have some significant involvement in the loss of the airplane, the Ethiopian investigators would have released the information immediately and singing their praises. I know I am going to get hammered for making a statement like that, but in truth, I hope I am wrong.”
Yes, agreed entirely. Apologies on being obscure in my message: I meant more to explain how it happens than to excuse the behavior. But I'm also liberal in my use of "Hanlon's razor".
We as a greater society, being generally aware of these phenomena, must raise the bar to fight our own inadequacies, just as you say.
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Trouble is decent journalists are very hard to find these days... Most news is circulated - repeated from each other, and / or the result of a google search. It drives me nuts seeing journalists interviewing politicians and simply failing to ask the right questions, and having rings run around them by anyone with half a brain...
Which reminds me....
YouTube
Which reminds me....
YouTube
The FAA is not funded or staffed to understand whatever the hell is going on inside modern "smart" flight controls. Maybe this should change.
I have confidence in the FAA in their traditional role of picking up debris they can understand and coming to a logical conclusion. 2 years ago a friend of mine died in a crash. I assumed the investigation would be super-superficial: a very young pilot alone in a very old kit-built he had just bought that day. Went up, down, splatt. Whatever happened, it would not affect many people, not like hundreds of new jetliners with hundreds of seats each. Not even worth discerning Pilot Error from Mechanic Error, because he was both. While the investigation took near 2 years, the Report was quite comprehensive. No sign of tail-cable break. A weak cylinder but not to cause the crash. Witness statements. He lifted and pulled up sharply, stalled it, and didn't recover.
Pretty much what I had guessed from the first. But it was some comfort to read the Report, know that someone had checked it all out. Also it reinforced an FAA "Recommendation" for more stall-training. Maybe that will encourage other teachers to insist on stall-work, even when the student is as blithely arrogant as my friend was.
I have confidence in the FAA in their traditional role of picking up debris they can understand and coming to a logical conclusion. 2 years ago a friend of mine died in a crash. I assumed the investigation would be super-superficial: a very young pilot alone in a very old kit-built he had just bought that day. Went up, down, splatt. Whatever happened, it would not affect many people, not like hundreds of new jetliners with hundreds of seats each. Not even worth discerning Pilot Error from Mechanic Error, because he was both. While the investigation took near 2 years, the Report was quite comprehensive. No sign of tail-cable break. A weak cylinder but not to cause the crash. Witness statements. He lifted and pulled up sharply, stalled it, and didn't recover.
Pretty much what I had guessed from the first. But it was some comfort to read the Report, know that someone had checked it all out. Also it reinforced an FAA "Recommendation" for more stall-training. Maybe that will encourage other teachers to insist on stall-work, even when the student is as blithely arrogant as my friend was.
That's misleading. They complete 2 per day, but it takes months to build an aircraft like a 737.
I thought it was clear, but I see your point. I actually don't think its months though, they really crank them out.
Should have said they deliver 2 per day.
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hehe. If you get the chance to drive around the Boeing Renton facility you'll find it takes a coffee break to do so. I think it's something like 5 km's.
A while ago, I was told that the big building at Everett was the largest building in the world (or maybe US), volume wise. Its not tall, but covers a large area.
Boeing guys complain if they get to work late, its a long hike from where they can park to their office, yeah its a big place.
Good thing they have lots of land, they need it now to park 737 Maxes
No.
DO-178B - Wikipedia
DO-178C - Wikipedia
https://www.faa.gov/aircraft/air_ce...software/media/AR-06-54_VerificationTools.pdf
https://inf.mit.bme.hu/sites/default/files/materials/taxonomy/term/445/13/13_CES_DO-178B.pdf
This is NTSB. NTSB Aviation Accident Database & Synopses
For the Max, the very wrongdoing of Boeing, is that they issued a Flight Operation manual with no mention of the Maneuvering Characteristics Augmentation System (MCAS) and no procedure for disengaging it. The wrongdoing of FAA is that it approved this Manual.
The prosecution and charging will be based on this fact, regardless of the Most Probable Cause of the first accident.
It was after the first accident that Boeing issued a SB and FAA issued an AD for to add the missing critical information and required steps for the pilots.
Boeing issues 737 Max fleet bulletin on AoA warning after Lion Air crash - The Air Current
https://theaircurrent.com/wp-content/uploads/2018/11/B737-MAX-AD-1107.pdf
George
So, can we imagine that the whole plane behavior depends on only one sensor? I fixed some card printing machines as part of my job. Not related to planes, sure, but I know what a mess can be made by only one erroneus, seemingy "insignificant" sensor...
Then, it comes down to the design, why only one?
Then, who is manufacturing those sensors? Under what conditions, which certificates, audits...etc...
You'll always get the Airbus vs Boeing argument, same as BMW vs XXXX. I'm just glad that all the 737s have been grounded until they can be proved to be safe to fly. The same thing happened with the Comet but a few more of them had to fall out of the sky before the manufacturer admitted that it was a design fault that caused them to break apart mid-air.
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I think this is a very important question.
Omitting to mention the new MCAS function in a go-to manual for critical situations, in combination with the MCAS system doing substantial changes towards flight correction when relying on data from a single source.
I may have misunderstood something, so this part may not be 100% correct: And the MCAS program rewritten to act through not the originally intended 0.6 degree but the value was increased to 2.5 degrees in the version rolled out the doors of the factory.
So either one of these factors by itself may not have a noticeable impact, but all these factors combined can be pretty dangerous in certain scenarios.
On the machines I work on, the critical controls require 2 or more sensors to agree before the signal is classified as valid. The systems are also only given 10% total authority over the whole of the controls. A 'miscompare' either invokes a 'voting' system where the outlier is rejected, or the system is invalidated and is flagged as being in a fault condition.
I read that another issue, besides the increase to 2.5 degrees of motion from 0.6, was that each time the system was reset and subsequently tripped again, a new datum would be established and the controls would move a further 2.5 degrees. There was no memory of previous movements made. This essentially gave the system full authority over a flight control surface via movement of the trim. And all with only one source of AoA data.
I don't yet understand the design decision to use only one source of data, but it will certainly be part of the investigation.
I read that another issue, besides the increase to 2.5 degrees of motion from 0.6, was that each time the system was reset and subsequently tripped again, a new datum would be established and the controls would move a further 2.5 degrees. There was no memory of previous movements made. This essentially gave the system full authority over a flight control surface via movement of the trim. And all with only one source of AoA data.
I don't yet understand the design decision to use only one source of data, but it will certainly be part of the investigation.
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