737 Max banned from Singapore airspace, grounded worldwide

[Nereus]

It is a preliminary report, the investigation is nowhere near complete.

https://www.msn.com/en-au/news/world/et ... spartandhp

"The crew performed all the procedures repeatedly...……………..

And probably included turning the system off and on repeatedly!

[J.J.B.]

Of critically important note, the crew performed the procedures as they had been laid down by Boeing for such an eventuality. You know as much about checklists as anyone here, if you are following them according to your training and what’s written in the POH, what else would you do? In a high stress environment such as a fanstop at 3,000’ I know I would try some of the drills in the relevant checklist at least once to attempt a restart.

This was a system glossed over by Boeing, with minimal training on its function and performance. In this case, it seems erroneous data were being fed to it that even trained pilots were unable to correct. Fatally.

Take a look at the preliminary report here:http://www.ecaa.gov.et/documents/20435/ ... af1ee17f3e

[Nereus]

This was a system glossed over by Boeing, with minimal training on its function and performance.

Absolutely no argument from me about that!

My point is that we are only going on a preliminary report issued by the airline. In the case of the Indonesian crash, also not a completed investigation, it was leaked that the captain carried out the same action 20 times, before giving up. In the Ethiopian case in appears that whatever happened, it occurred much closer to the ground, giving them a lot less time to eliminate the cause, but as of now it is has not been published just what the crew did attempt.

[J.J.B.]

"The crew performed all the procedures repeatedly...……………..

And probably included turning the system off and on repeatedly!

The preliminary report suggests this is not the case. Their repeated actions were pulling back desperately on the stick in an attempt to raise the nose. It’s not clear, to me at least, whether the MCAS system can be turned on or off from within the cockpit. If it can, it wasn’t included in the revised data provided by Boeing and the crew followed the checklist.

[PeteC]

Logically the solution to all of this for Boeing is to just remove the system completely from all aircraft. I don't recall reports of planes stalling and falling out of the sky before so why introduce all these new innovations when statistics show little benefit. It's removal would give the buyers and the flying public much peace of mind as well.

[Nereus]

Logically the solution to all of this for Boeing is to just remove the system completely from all aircraft. I don't recall reports of planes stalling and falling out of the sky before so why introduce all these new innovations when statistics show little benefit. It's removal would give the buyers and the flying public much peace of mind as well.

From what has been published the MACS system was required for certification because of the size and moved position of the new engines. Their new position caused a big change in the aerodynamic characteristics.

[Nereus]

"The crew performed all the procedures repeatedly...……………..

And probably included turning the system off and on repeatedly!

The preliminary report suggests this is not the case. Their repeated actions were pulling back desperately on the stick in an attempt to raise the nose. It’s not clear, to me at least, whether the MCAS system can be turned on or off from within the cockpit. If it can, it wasn’t included in the revised data provided by Boeing and the crew followed the checklist.

Yes, the system CAN be turned off, the same as it has always been on B737's.

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[Nereus]

Here is a couple of photos of the trim wheel. In a video that I posted previously it can be seen how it operates. The B737 also has a "speed trim system" STS, which operates during take off mostly. Turn OFF the system and the motor is isolated so MACAS or otherwise, it stops running away. The drill is, or SHOULD BE, to follow "run away trim condition".

handle closed

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B737 trimwheel handle extended.jpg (52.73 KiB) Viewed 724 times

[PeteC]

Logically the solution to all of this for Boeing is to just remove the system completely from all aircraft. I don't recall reports of planes stalling and falling out of the sky before so why introduce all these new innovations when statistics show little benefit. It's removal would give the buyers and the flying public much peace of mind as well.

From what has been published the MACS system was required for certification because of the size and moved position of the new engines. Their new position caused a big change in the aerodynamic characteristics.

The new version of the 777 was just introduced. We'll have to see if the engines are more forward on that as well.

[STEVE G]

Logically the solution to all of this for Boeing is to just remove the system completely from all aircraft. I don't recall reports of planes stalling and falling out of the sky before so why introduce all these new innovations when statistics show little benefit. It's removal would give the buyers and the flying public much peace of mind as well.

From what has been published the MACS system was required for certification because of the size and moved position of the new engines. Their new position caused a big change in the aerodynamic characteristics.

Yes, basically the larger size engine cowling, mounted further forward, generated lift at high angles of attack that caused a pitch up moment which would resist attempts to recover from a stall condition and that was what this system was supposed to stop. The flaw seems to be that the system could be triggered by one angle of attack sensor failure.

[Nereus]

Here is yet another "report":

Six Minutes To Disaster: How Ethiopian Air Pilots Battled Boeing Max

https://www.ndtv.com/world-news/we-at-b ... eo-2018282

While it's not clear from the report exactly what steps the pilots took, their struggles to keep the plane climbing apparently led them to switch power back on to the trim system. About 30 seconds before they crashed, it was activated by the pilots to slightly raise the nose.

[Nereus]

Of critically important note, the crew performed the procedures as they had been laid down by Boeing for such an eventuality. You know as much about checklists as anyone here, if you are following them according to your training and what’s written in the POH, what else would you do?

The following is all that I can find, and that from a guy I know that fly's B737's:

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[Nereus]

There are some interesting comments in the following if you sift through some of the garbage. in the blog section both Bjorn and Mark have posted some plausible comments.

https://leehamnews.com/2019/03/29/bjorn ... sh-part-3/

[STEVE G]

This is what Boeing is doing to correct the situation:

"Boeing has developed an MCAS software update to provide additional layers of protection if the AOA sensors provide erroneous data. The software was put through hundreds of hours of analysis, laboratory testing, verification in a simulator and two test flights, including an in-flight certification test with Federal Aviation Administration (FAA) representatives on board as observers.

The additional layers of protection include:

Flight control system will now compare inputs from both AOA sensors. If the sensors disagree by 5.5 degrees or more with the flaps retracted, MCAS will not activate. An indicator on the flight deck display will alert the pilots.

If MCAS is activated in non-normal conditions, it will only provide one input for each elevated AOA event. There are no known or envisioned failure conditions where MCAS will provide multiple inputs.

MCAS can never command more stabilizer input than can be counteracted by the flight crew pulling back on the column. The pilots will continue to always have the ability to override MCAS and manually control the airplane."

You can read backwards into that to get some understanding about what they got wrong in the first place, particularly the last item where the system could potentially trim the aircraft out of a flyable condition, which is what happened in at least one of these incidents in that by the time the stab trim cutout was activated, there was too much nose down trim for the aircraft stay airborne with the condition that it was in.

[Nereus]

Boeing 737 Max may not return to service until August

https://www.bangkokpost.com/news/world/ ... recent_box

SEOUL: The International Air Transport Association (IATA) expects it could take until August before the Boeing Co 737 Max returns to service, the airline group's head said on Wednesday, adding that the final say on the timing rested with regulators.

The 737 Max was grounded globally in March after a crash in Ethiopia killed all 157 people on board, the model's second deadly crash in five months.

"We do not expect something before 10 to 12 weeks in re-entry into service," IATA Director General Alexandre de Juniac told reporters in Seoul. "But it is not our hands. That is in the hands of regulators."

IATA plans to organise a summit with airlines, regulators and the manufacturer in 5 to 7 weeks to discuss what is needed for the 737 Max to return to service, he said.

At an IATA meeting in Montreal last week, airline members said they wanted regulators to cooperate closely on the decision for the plane's re-entry to service, de Juniac said.
"We hope that they will align their timeframe," he said of regulators.

The Federal Aviation Administration (FAA) expects to approve the jet's return to service as soon as late June, representatives of the US air regulator informed members of the United Nations' aviation agency in a private briefing last week, sources told Reuters.

US operators United Airlines, Southwest Airlines, and American Airlines have removed the planes from their flight schedules until early to mid August.

A number of grounded Southwest Airlines Boeing 737 MAX 8 aircraft are shown parked at Victorville Airport in Victorville, California, US, March 26, 2019. (Reuters file photo)

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