Another brand new 737 Max crashes

[kach22i]

Originally Posted by widebody911

https://www.seattletimes.com/business/boeing-aerospace/failed-certification-faa-missed-safety-issues-in-the-737-max-system-implicated-in-the-lion-air-crash/

Both Boeing and the FAA were informed of the specifics of this story and were asked for responses 11 days ago, before the second crash of a 737 MAX last Sunday.

Oh boy.

Since MCAS was supposed to activate only in extreme circumstances far outside the normal flight envelope, Boeing decided that 737 pilots needed no extra training on the system — and indeed that they didn’t even need to know about it. It was not mentioned in their flight manuals.

That stance allowed the new jet to earn a common “type rating” with existing 737 models, allowing airlines to minimize training of pilots moving to the MAX.

Understatement of 2019........................

Boeing’s safety analysis of the system assumed that “the pilots would recognize what was happening as a runaway and cut off the switches,” said the engineer. “The assumptions in here are incorrect. The human factors were not properly evaluated.”

[flipper35]

The trouble i have with that article is they state the MCAS only "activates" in extreme flight conditions. The anti-stall portion of MCAS activates then, but the system is always active to make the MAX feel the same in terms of flight characteristics of the earlier models like the NG. Otherwise it is a good article.

The MCAS was designed to allow pilots to fly the MAX without additional training by making the plane appear to behave like the older ones even though there were significant changes. The system was in the manual but I doubt many felt the need to mention the system since it was supposed to be unnoticed in the background as far as the pilots were concerned. After Lion air, there should not have been a pilot on the planet that was unaware of it, the characteristics of it and how to disable it.

The AoA issue as stated by an engineer on another forum after the Lion Air says that the system takes an out of proper parameters of one sensor and ignores the other, regardless of which sensor show the high AoA. It does not compare the two or vote or compare the readings to corroborate the possibly erroneous reading. Like having one kid tell you the house is on fire and the other kid says not. It automatically believes the kid that says the house is on fire, even if there is no other evidence. I am not sure this is exactly how it works, but i have seen it from a couple different ones.

[beepbeep]

Originally Posted by flipper35

The AoA issue as stated by an engineer on another forum after the Lion Air says that the system takes an out of proper parameters of one sensor and ignores the other, regardless of which sensor show the high AoA. It does not compare the two or vote or compare the readings to corroborate the possibly erroneous reading. Like having one kid tell you the house is on fire and the other kid says not. It automatically believes the kid that says the house is on fire, even if there is no other evidence. I am not sure this is exactly how it works, but i have seen it from a couple different ones.

From my reading on PPrune, it seems that MCAS basically alternates between single AoA sensors for each flight. No vote, no comparison...just picks 1,0,1,0,1,0 etc.

This is very puzzling decision, considering the harm that non-working MCAS can cause. How on earth did FAA really certified this as safe?? A bird hits wrong AoA sensor and weeee....10 seconds of pitch down you must fight with...repeatedly...

A350 where multiple sensors are sampled and voted by FBW logic for confidence looks like hedgehog:


Cited from news article above:
"The original Boeing document provided to the FAA included a description specifying a limit to how much the system could move the horizontal tail — a limit of 0.6 degrees, out of a physical maximum of just less than 5 degrees of nose-down movement."

"After the Lion Air Flight 610 crash, Boeing for the first time provided to airlines details about MCAS. Boeing’s bulletin to the airlines stated that the limit of MCAS’s command was 2.5 degrees."

Oh boy...

[kach22i]

Originally Posted by flipper35

The trouble i have with that article is they state the MCAS only "activates" in extreme flight conditions. The anti-stall portion of MCAS activates then, but the system is always active to make the MAX feel the same in terms of flight characteristics of the earlier models like the NG. Otherwise it is a good article.

Thank you for the clarification, and it's an important one.

[widebody911]

How on earth did FAA really certified this as safe??

Apparently they didn't - Boeing did and the FAA rubberstamped it

[flipper35]

Also, the MCAS is only in effect when the aircraft is hand flown. Its sole purpose is for the pilot to think it flies the same as the older birds. As in so they don't have to be type rated in a different block aircraft.

Beepbeep, that could be, he may have no been clear in that it takes the high aoa warning from either sensor.

[sammyg2]

More info on the A330 control malfunction i mentioned earlier where the 'puter decided that the altitude was actually an AOA reading and dropped rapidly (10 degrees, almost 700 feet instantly).
Happened to three A330s, they never figured out why.
I'm sure it'll never happen again. I can't wait until computers are driving all the cars on the freeway

[PetrolBlueSC]

I predict that Boeing and Airbus will never allow their planes to be flown without pilots. If there is no pilot, who would they blame for design and training failures?

[beepbeep]

Originally Posted by widebody911

How on earth did FAA really certified this as safe??

Apparently they didn't - Boeing did and the FAA rubberstamped it

This is fcuked up on so many levels. Boeing gives FAA wrong info ("it's only 0.5 degrees, I swear"), on which FAA says "oh, go ahead and certify it yourself". So they do...except they tweaked it to 2.5 degrees as 0.5 didn't work...

[javadog]

From the article linked above:

"On the Lion Air flight, when the MCAS pushed the jet’s nose down, the captain pulled it back up, using thumb switches on the control column. Still operating under the false angle-of-attack reading, MCAS kicked in each time to swivel the horizontal tail and push the nose down again.

The black box data released in the preliminary investigation report shows that after this cycle repeated 21 times, the plane’s captain ceded control to the first officer. As MCAS pushed the nose down two or three times more, the first officer responded with only two short flicks of the thumb switches.

At a limit of 2.5 degrees, two cycles of MCAS without correction would have been enough to reach the maximum nose-down effect.

In the final seconds, the black box data shows the captain resumed control and pulled back up with high force. But it was too late. The plane dived into the sea at more than 500 miles per hour."

After correcting the problem 21 times, why did it not occur to the captain to turn off the damn stabilizer trim switches? I'd wager that he should have realized he had a problem with the stabilizer trimming itself without being commanded.

[billybek]

https://www.msn.com/en-ca/money/topstories/air-canada-grounds-boeing-max-8s-until-at-least-july-1/ar-BBUXV5k?ocid=spartandhp

[Eric Coffey]

Originally Posted by javadog

I’m fairly certain that a competent pilot would recognize the fact that the stabilizer trim is being manipulated without pilot input. That is something that they do train for, it really doesn’t matter why the stabilizer is moving uncommanded. The fix is the same and it’s been that way for 50 years.

Yep, it's essentially a runaway trim issue. The procedure for dealing with such is in the manual, QRH, and is also a primary memory-item. The only real issue is that the initial action/ability to halt the auto-trim by manually pulling back on the yoke/column no longer works on an A/C with an MCAS fault. However, the follow-on procedure if the problem persists remains the same (stab. trim cut-out switches). So, any competent 737 driver should be able to deal with the problem effectively, even if they had no idea what MCAS was.

Originally Posted by javadog

I don’t mean any disrespect to the pilots that crashed these two jets but I truly believe that that would not of happened with the frontline pilots we have here in this country.

With only 200 hours total, the FO of the last one wouldn't even be allowed in the right seat if it was a US flight.

[Eric Coffey]

Originally Posted by javadog

After correcting the problem 21 times, why did it not occur to the captain to turn off the damn stabilizer trim switches? I'd wager that he should have realized he had a problem with the stabilizer trimming itself without being commanded.

+1

From post #82:

Originally Posted by Eric Coffey

Not only that, but I believe it's only "active" when flying manually, and/or with flaps up, and/or with extreme pitch/bank angles. It can also be temporarily overridden via elec. trim switches on the yoke, or manual trim wheels.
Further, it would seem that the standard procedure for runaway trim is applicable to faulty MCAS, albeit a bit updated now.

I can't imagine how/why a pilot would attempt to "fight" a problem like that for any lengthy period of time before initiating runaway trim procedures, all the way to stab. trim cut-out. However, that appears to be a possibility with the Lion Air crew, and maybe even the Ethiopian flight (alt. oscillations noted). As mentioned, the previous crew on the Lion Air A/C had essentially the exact same problem. They dealt with it appropriately and continued their flight without issue.

That said, I still think the big problem is the lack of training/awareness of the new system, and the differences in the initial runaway trim procedure.
As I mentioned previously, one could halt runaway trim on the "old" 737 by simply pulling back on the column (break-away). That won't work on an MCAS equipped A/C. You have to disable the trim altogether (cut-out).
While that was always the final step in the "old" 737 runaway trim procedure, the initial step of pulling back on the yoke no longer works with a faulty MCAS system. Sort of counter-intuitive, IMO.

I think the system/procedures/manuals need a minor update to address the fact that trim break-away via control column is no longer effective.
Although, again, I can't imagine any competent 737 driver would just keep pulling back on the yoke, with no results, all the way to the ground.

[daepp]

Originally Posted by Seahawk

The start of a flight and the terminal phase of a flight are when the aircrew is most diligent...that is when the majority of aircraft accidents happen.

I have no training in this area whatsoever, but I would think those stats gain even greater weight when you consider the takeoff and terminal phases are measured in minute, whereas the cruise phase is typically measured in hours.

[Neilk]

Well looks like the penultimate Lion Air flight had a savior in the form of a deadheading jumpseat pilot per Bloomberg

That extra pilot, who was seated in the cockpit jumpseat, correctly diagnosed the problem and told the crew how to disable a malfunctioning flight-control system and save the plane, according to two people familiar with Indonesia’s investigation.

Points to bad training but also poor communication of new features by Boeing.

[onewhippedpuppy]

Originally Posted by widebody911

How on earth did FAA really certified this as safe??

Apparently they didn't - Boeing did and the FAA rubberstamped it

This isn’t as ominous as it sounds. The FAA appoints designees (DERs) in a very diverse and wide variety of discriplines, who have the ability to sign off on aircraft certification aspects on behalf of the FAA. This is in addition to the OEM maintaining a ODA which is essentially a certification organization per FAA regulations, which the designees are a part of. Because the FAA does not practically have the ability to review and approve every aircraft certification project, these people practically speaking are the FAA for these projects. The designees are subject matter experts and it’s very difficult to obtain and hold a DER, and the ODA is subject to a lot of regulation and frequent FAA audits. There are a lot of rules and protections in place to keep the DERs from being subjected to undue pressure by company leadership including revocation of ODA authority which I have seen happen. So it’s not necessarily a “Boeing employee rubber stamp” as some are saying.

Originally Posted by onewhippedpuppy

This isn’t as ominous as it sounds. The FAA appoints designees (DERs) in a very diverse and wide variety of discriplines, who have the ability to sign off on aircraft certification aspects on behalf of the FAA. This is in addition to the OEM maintaining a ODA which is essentially a certification organization per FAA regulations, which the designees are a part of. Because the FAA does not practically have the ability to review and approve every aircraft certification project, these people practically speaking are the FAA for these projects. The designees are subject matter experts and it’s very difficult to obtain and hold a DER, and the ODA is subject to a lot of regulation and frequent FAA audits. There are a lot of rules and protections in place to keep the DERs from being subjected to undue pressure by company leadership including revocation of ODA authority which I have seen happen. So it’s not necessarily a “Boeing employee rubber stamp” as some are saying.

I agree it's not a rubber stamp, but you can bet those people are subject to implicit yet intense pressure to pass things along. Their compensation and career progression is in the hands of Boeing. Yes, this process is a force multiplier, and those folks are highly trained, serious people, but the system has an irreconcilable conflict of interest.

The DOJ has convened a grand jury to look at it, and if I were still there, I'd be on the team responding.

[jyl]

I have no qualifications to comment on 737s or airplanes, but do have a general thought about technology. With systems this complex, there is a judgment call on how much of the complexity do you ask the human to deal with vs how much do you have the system to handle. You can put it all on the human and risk causing an accident that way. You can hide it all from the human and risk causing an accident that way. After each accident, it is easy to say of course that particular aspect should have been manually controlled because of course the perfectly skilled and highly experienced pilot would have done exactly the right thing based on his perfect training and everything would have been fine. Designing systems by lawsuit and hindsight isn't the ideal way to do it. Maybe Boeing got this particular decision wrong but I wouldn't jump to the conclusion that the way it builds, tests and certifies airplanes is wrong. The right process can still lead to wrong decisions.

[Sooner or later]

I don't know if this has been brought up


https://www-bloomberg-com.cdn.ampproject.org/v/s/www.bloomberg.com/amp/news/articles/2019-03-19/how-an-extra-man-in-cockpit-saved-a-737-max-that-later-crashed?amp_js_v=a2&amp_gsa=1#amp_tf=From%20%251%24s&ampshare=https%3A%2F%2Fwww.bloomberg.com%2Fnews%2F articles%2F2019-03-19%2Fhow-an-extra-man-in-cockpit-saved-a-737-max-that-later-crashed

Jumpseat rider played critical role in Indonesian cockpit

An off-duty pilot saved the 737 Max from a crash. The next day, the same plane on flight JT610 crashed into the sea.
As the Lion Air crew fought to control their diving Boeing Co. 737 Max 8, they got help from an unexpected source: an off-duty pilot who happened to be riding in the cockpit.

That extra pilot, who was seated in the cockpit jumpseat, correctly diagnosed the problem and told the crew how to disable a malfunctioning flight-control system and save the plane, according to two people familiar with Indonesia’s investigation.

The next day, under command of a different crew facing what investigators said was an identical malfunction, the jetliner crashed into the Java Sea killing all 189 aboard.

[javadog]

I've seen that. One more suggestion that the pilots were not up to snuff. Reports are that their was a great deal of panic expressed in the voices heard in the cockpit voice recorder.

When a pilot (the captain) adjusts the trim 21 times and fails to figure out he has an uncommanded trim problem, or recognizes it and doesn't know how to stop it, I'm going to say he shouldn't have been a captain. I understand that there was a lot going on but he had the presence of mind and time to keep adjusting the trim.