737 Max banned from Singapore airspace, grounded worldwide

[J.J.B.]

Clearly a different case. Different reason? Not so sure. Faulty sensors led to erroneous readings fed to the autopilot that the two First Officers (the Captain was on a break) misinterpreted. They reacted differently, the aircraft computer tried to compensate and it all ended tragically for everyone onboard. The Airbus sidestick layout, compared with the Boeing central yoke, meant neither pilot could clearly see the input of the other, which was a contributory factor in the crash.

So we have incorrect readings from sensors causing an automated system to invoke inappropriate corrections and a crew not sure how to react to it in both cases. Different circumstance, absolutely, different reason for crash, not really.

[GroveHillWanderer]

I think this is the crucial part of the Seattle Times article (I have also read almost identical analyses in other publications):

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.

Dennis Tajer, a spokesman for the Allied Pilots Association at American Airlines, said his training on moving from the old 737 NG model cockpit to the new 737 MAX consisted of little more than a one-hour session on an iPad, with no simulator training.

Minimizing MAX pilot transition training was an important cost saving for Boeing’s airline customers, a key selling point for the jet, which has racked up more than 5,000 orders.

The company’s website pitched the jet to airlines with a promise that “as you build your 737 MAX fleet, millions of dollars will be saved because of its commonality with the Next-Generation 737.”

In the aftermath of the crash, officials at the unions for both American and Southwest Airlines pilots criticized Boeing for providing no information about MCAS, or its possible malfunction, in the 737 MAX pilot manuals.

As I see it, Boeing basically hid information about this aspect of the aircraft's design in order to maximise sales of their new aircraft. They only raised awareness of it by circulating an advisory after the Lion Air crash had already happened and even that advisory seems to have been inadequate since the Ethiopian Airlines pilots in this latest crash seemed unaware of it.

To me, it seems extremely (if not criminally) negligent to have not mentioned it in the flight manuals and to have not required pilots to undergo training on it, just so they could tout the aircraft as having almost identical flight characteristics to previous 737 models in order to increase sales.

[Nereus]

I think this is the crucial part of the Seattle Times article (I have also read almost identical analyses in other publications):

Yes, I have also read that article. Another thing that I did read was where it was mentioned that the MCAS system was required for certification. But we only have endless reports and speculation to go on.

It should also be noted that ALL 737 series aircraft have "mechanical" controls. They are not "fly-by-wire".

It seems that both accidents MAY have been caused by excessive nose down deployment of the horizontal stabiliser, for whatever reason. But the correct action by the pilots SHOULD have arrested the nose down very soon after it commenced. As I posted previously, it appears that in the case of the Indonesian accident the captain made 21 attempts to stop it just by repeating the same action over and over!

What we can be sure of is that this is going to be a long and expensive drawn out process for all involved!

[GroveHillWanderer]

It seems the US Justice Department may also think that there was criminal negligence on Boeing's part.

"The Justice Department is investigating Boeing’s development process for the 737 Max jetliner after two high-profile accidents appear to involve the planes’ anti-stall systems, The Wall Street Journal reports.
[...]
A grand jury in Washington, D.C., issued a subpoena for documents from one person involved in the development process ...

The Justice Department’s involvement could signal that criminal charges are on the table for those involved in the Max’s development."

[GroveHillWanderer]

But the correct action by the pilots SHOULD have arrested the nose down very soon after it commenced. As I posted previously, it appears that in the case of the Indonesian accident the captain made 21 attempts to stop it just by repeating the same action over and over!

But how were the pilots on the Lion Air crash supposed to know what the correct action was? The cockpit flight voice records indicated they were desperately searching through the flight manuals to find the correct action to take but we now know that their efforts were in vain, as the flight manuals did not have information about the MCAS system.

As stated by aviationcv.com:

[Boeing 737 Max]Flight manuals also lacked any information about the [MCAS] system, which investigators are claiming to be responsible for the deadly accidents.

A number of pilots who had been flying the 737 Max 8 or 9 had complained about it anonymously on a Federal Aviation website, saying among other things that it was:

"unconscionable" that Boeing, the US aviation regulatory agency (the Federal Aviation Administration) and the unnamed airline would have pilots flying without adequate training or sufficient documentation.

The same entry also charges that the flight manual "is inadequate and almost criminally insufficient."

[Nereus]

But how were the pilots on the Lion Air crash supposed to know what the correct action was? The cockpit flight voice records indicated they were desperately searching through the flight manuals to find the correct action to take but we now know that their efforts were in vain, as the flight manuals did not have information about the MCAS system.

I don't know as I haven't flown a B737. But from what I have read it would be damn obvious that there was some sort of "runaway" elevator fault. So, turn the bloody thing off, AND disconnect the auto pilot! This is something that is taught to private pilots, never mind airline pilots. FLY the bloody aircraft!

I do know that the B737 has a big elevator trim wheel on the centre console right up against the pilots knee.(one each side).The control input can be either by electrical trim switches on the control yoke, this new fangled MCAS system or manually by winding the wheel. The trim wheel moves regardless of what is driving it, as it is connected by a steel cable to the actuator input drive, along with an electric motor. The wheel also is very lowly geared for manual use and when driven by the electric motor whirls around very quickly. In fact, it moves that slowly in manual that it has a fold out handle on it that can be deployed so the pilot can wind it quickly. If the handle should be accidently left in the operating position it has a very good chance of whacking the pilot in the leg!

There can be no doubt that Boeing have a lot to answer for, but as I have posted previously, out of 350 B737 Max in use, only two have crashed.

[GroveHillWanderer]

Only two have crashed, mainly because only a couple of them have developed the fault in the AOA sensor that determines whether the MCAS system intervenes. There is a second AOA sensor that could have been used to cross-check the first sensor and Boeing had even designed a feature that would do just that but instead of making it a standard feature included on all planes, they decided to make it an optional extra. The FAA has now mandated that this additional safety feature (called a "disagree" light) should be fitted on all 737 Max aircraft and Boeing plans to make the light available free of charge as part of a forthcoming software update but many people are saying this is too little, too late and it should have been standard from the outset.

Going back to your other points though, how could the pilots know to turn off the MCAS system that was causing the problem, when they didn't know it existed? Also for the auto-pilot - they didn't know the problem was being caused by an automatic control system (MCAS) that was engaged along with the auto-pilot so they couldn't have known that disengaging the auto-pilot would turn it off. Yes, I suppose they could have tried switching various things on and off at random to see what would happen but that doesn't seem very scientific.

If Boeing had just said, "No, this aircraft doesn't fly just like the other 737 models, it has a wholly new automated control feature that can force the plane's nose down and here's how to switch that feature off" (and included that in the flight manuals and required the pilots to undergo training on how to handle this new feature should it malfunction) both of these crashes could have been avoided. Instead, Boeing said pilots didn't need any additional training beyond a 1 hour iPad simulation, just so they could get the plane on the market quicker and cheaper, in a bid to win back market share from the Airbus a320neo.

As I said before, it looks as if Boeing could possibly be facing criminal charges over this and from everything I've read, I think they could well deserve it.

[STEVE G]

But how were the pilots on the Lion Air crash supposed to know what the correct action was? The cockpit flight voice records indicated they were desperately searching through the flight manuals to find the correct action to take but we now know that their efforts were in vain, as the flight manuals did not have information about the MCAS system.

I do know that the B737 has a big elevator trim wheel on the centre console right up against the pilots knee.(one each side).The control input can be either by electrical trim switches on the control yoke, this new fangled MCAS system or manually by winding the wheel. The trim wheel moves regardless of what is driving it, as it is connected by a steel cable to the actuator input drive, along with an electric motor. The wheel also is very lowly geared for manual use and when driven by the electric motor whirls around very quickly. In fact, it moves that slowly in manual that it has a fold out handle on it that can be deployed so the pilot can wind it quickly. If the handle should be accidently left in the operating position it has a very good chance of whacking the pilot in the leg.........

This is what I've been thinking about, I haven't worked on a B737 for about 20 years and that was a -200, and as you say, when the stabilizer trimmed, you had this trim wheel flying around by your knee and it was very obvious what was going on. When I read about these issues, I assumed that they must have got rid of that on the Max for the crews not to realise what was happening but I've just looked at a picture of the cockpit and it's still fitted.

[Nereus]

Going back to your other points though, how could the pilots know to turn off the MCAS system that was causing the problem, when they didn't know it existed

They didn't need to know it existed. They just needed to recognise a "runaway" condition with the elevator, as I have previously posted, and fly the aeroplane. With the Ethiopian accident it has not been reported what caused it, but with the Lion Air in Indonesia it has been reported from the CVR / FDR that the captain attempted the same desperate input 21 times before giving up and handing it to the FO. Draw your own conclusion from that.

I had a "runaway" control fault many years ago on a helicopter that I was flying. There was no such thing as MCAS in those days, or auto pilot, just a "coolie hat" electric trim on the cyclic. But I had been trained to recognise the condition, and it had been demonstrated to me that control was still possible, albeit needing a lot more muscle on the control stick. Plus a quick rush to the nearest toilet after landing!

[Nereus]

Here is yet another "report". All that we keep hearing is that the one and only Angle of Attack(AoA) sensor was the villain that caused this crash. Also, reported variations in altitude and airspeed. Really? If the aircraft is either climbing OR descending, then BOTH airspeed AND altitude ARE going to change. BUT, strangely enough, there are SEVERAL other instruments in front of BOTH pilots that indicate both climb and decent, angle of bank, the horizon, and in the case of a BIG instrument called a HSI(horizontal situation indicator) ALL THREE conditions.
………………………………………………………………………………………………………………………………………

Black box reveals final moments of doomed Lion Air flight

https://au.news.yahoo.com/black-box-rev ... 36682.html

The pilots of a doomed Lion Air Boeing 737 MAX scrambled through a handbook to understand why the jet was lurching downwards in the final minutes before it hit the water killing all 189 people on board.

Three anonymous people with knowledge of the cockpit voice recorder contents revealed to Reuters the final moments recorded by the plane’s black box.

They said the Indonesian first officer in the cockpit began to pray in their final moments as the plane plummeted.

The investigation into the crash last October has taken on new relevance as the US Federal Aviation Administration (FAA) and other regulators grounded the model last week after a second deadly accident in Ethiopia.

Investigators examining the Indonesian crash are considering how a computer ordered the plane to dive in response to data from a faulty sensor and whether the pilots had enough training to respond appropriately to the emergency, among other factors.

Following the second fatal accident, US authorities are reviewing whether enough was done to ensure the plane was safe to fly, while attention has also focused on the training of the Lion Air crew and whether aeroplane manuals are clear enough.

Flight control problem

The captain was at the controls of Lion Air flight JT610 when the nearly new jet took off from Jakarta, and the first officer was handling the radio, according to a preliminary report issued in November.

Just two minutes into the flight, the first officer reported a “flight control problem” to air traffic control and said the pilots intended to maintain an altitude of 5000 feet, the November report said.

The first officer did not specify the problem, but one source said airspeed was mentioned on the cockpit voice recording, and a second source said an indicator showed a problem on the captain’s display but not the first officer’s.
The captain asked the first officer to check the quick reference handbook, which contains checklists for abnormal events, the first source said.

For the next nine minutes, the jet warned pilots it was in a stall and pushed the nose down in response, the report showed. A stall is when the airflow over a plane’s wings is too weak to generate lift and keep it flying.

The captain fought to climb, but the computer, still incorrectly sensing a stall, continued to push the nose down using the plane’s trim system. Normally, trim adjusts an aircraft’s control surfaces to ensure it flies straight and level.

“They didn’t seem to know the trim was moving down,” the third source said. “They thought only about airspeed and altitude. That was the only thing they talked about.”

Boeing Co declined to comment on Wednesday because the investigation was ongoing.

Regulatory scrutiny

The U.S. Transportation Department’s inspector-general now plans to audit the FAA’s certification of the Boeing 737 MAX, while European and Canadian regulators say they want to make up their own minds whether a promised software upgrade is adequate.

The manufacturer has said that to handle the situation there is a documented procedure that must be memorised. A different crew on the same plane the evening before encountered the same problem but solved it after running through three checklists, according to the November report.

[Nereus]

For those interested I post this just as an illustration of what happens with a "runaway trim" situation where the control elevator suddenly causes a rapid pitch change. This is filmed in a simulator and is NOT a B737 Max, but rather a B737 CL, (-300/400/500 Classic). As far as I am aware the general control layout and functions are basically the same on a MAX. Although the pilot flying was aware of what was going to happen, and so was prepared, it does illustrate how rapidly things happen, which should be considered in the case of the crashed aircraft.(at least in the case of Lion Air).

In particular it shows the "manual trim wheel" and how it is plainly obvious, without even directly looking at it, as it is driven around until switched off.

It also illustrates how the crew SHOULD work together, these days referred to as "CRM".(https://www.flightdeckfriend.com/ask-a- ... hat-is-crm)

[STEVE G]

Another point is that on an aircraft like the 737 with a manual stabilizer trim control wheel, you can actually physically stop it moving by holding the wheel as there is a clutch in the drive assembly and due to the gearing advantage, you can stop the stabilizer from moving.
Just to clarify, it is the whole stabilizer that is moving and not the elevator, that is why you can't just move the control column and fly out of a situation like that, the elevator doesn't have enough control force to overcome a seriously out of trim stabilizer.

[Nereus]

Just to clarify, it is the whole stabilizer that is moving and not the elevator,

Yes, quite correct, Steve.

The yoke does move the elevators, whereas the trim moves the horizontal stabilizer. The stabilizer is much larger than the elevators, and therefore is more effective than the elevator at extreme angles. Even with full backpressure, the nose would continue to pitch down.

Nonetheless, all 737NGs/MAXs have trim cutout switches, 1 for the autopilot and 1 for the normal electric trim. Using these would immediately disable the electric trim. These are generally part of a standard trim runaway situation, but the crew did not recognize the situation and failed to use them.

https://aviation.stackexchange.com/ques ... the-boeing

[Nereus]

And for what it's worth:
……………………………………………………………………………………………………………………………….
https://www.satcom.guru/2018/11/stabilizer-trim.html

[J.J.B.]

https://edition.cnn.com/africa/live-new ... index.html

Well, well. Seemingly not pilot error after all.