Todays plane tragedy

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Originally Posted by Wales-Bales

You have to engage the autotpilot system to override the MCAS system when flying in manual mode?

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Yes that’s correct.

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Originally Posted by Sky High Bluebird

Yes that’s correct.

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So if you you were flying on autopilot and needed to switch to manual control in an emergency, the only way to override MCAS would be to go back into autopilot mode?

Note the requirements for the engagement of MCAS at the top left of,the picture.

The autopilot has to be off.

Attachment 2983

The easiest way to disarm it is to “blip” the electric trimmer on the control column (see bottom right) or engage/re engage the autopilot.

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Originally Posted by Sky High Bluebird

Note the requirements for the engagement of MCAS at the top left of,the picture.

The autopilot has to be off.

The easiest way to disarm it is to “blip” the electric trimmer on the control column (see bottom right) or engage/re engage the autopilot.

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In my example, I was assuming that the MCAS had kicked in after the pilot had switched to manual mode. So blipping the electric trimmer is a separate process to engaging the auto-pilot? I don't know much about flying passenger planes, I'm just trying to understand how the software works.

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Originally Posted by Sky High Bluebird

It should have been easy enough to disable the MCAS system but due to inadequate training (not the crews fault I should add),they were unable too.

Also with regards to the AoA sensor note that the MCAS system only works when the autopilot is off, so engaging the autopilot with the push of a button or a flick of the electric trimmer on the control column would have overridden the MCAS.

Whilst the 737 dates back to 1966 , the MAX version is very much state of the art flightdeck and is very computerised ,it has more In common with the Dreamliner (another aircraft which had teething problems) than it does with earlier generations of the aircraft.

With over 5000 on order I think it is for from doomed imho.

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This statement regarding the Air Lion crash report would seem to contradict what you said.

"Documents reveal that pilots flying last November reported engaging autopilot only for the aircraft's nose to pitch lower, prompting the warning system to exclaim: "Don't sink! Don't sink!"

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Originally Posted by Vindec

The CAA have acted in accordance with public opinion and the undeniable fact these planes have software issues that need to be resolved. Of course none have crashed in the UK as there are so few operating over UK skies. But you shouldn't wait for planes to crash before you act although it seems in this case that is exactly what has happened.

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That was my point. The post I repleid to said they'd acted far too late. Which clearly they hadn't.

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Originally Posted by xsnaggle

This statement regarding the Air Lion crash report would seem to contradict what you said.

"Documents reveal that pilots flying last November reported engaging autopilot only for the aircraft's nose to pitch lower, prompting the warning system to exclaim: "Don't sink! Don't sink!"

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That's Interesting however id be curious as to the source of the documents mentioned.

Looking at the official KNKT Preliminary Aircraft accident invesitigation report

https://reports.aviation-safety.net/...RELIMINARY.pdf

If you look at page 11 with regards to the CVR transcript you'll note that the SIC (co-pilot) confirms to ATC that the aircraft is being flown manually due to a flight control problem, that was 2 mins and 17 seconds before impact.

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Originally Posted by Wales-Bales

In my example, I was assuming that the MCAS had kicked in after the pilot had switched to manual mode. So blipping the electric trimmer is a separate process to engaging the auto-pilot? I don't know much about flying passenger planes, I'm just trying to understand how the software works.

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Yes it’s a separate process.

If the pilot makes a manual trim command the MCAS will not re-activate until there have been 5 continuous seconds without pilot trim command.

What I would say it’s one thing being able to discuss the details of a complex system in a warm room with a cup of tea.
However I can only begin to imagine the confusion and startle factor with dealing with a situation like this, throw in the likelihood of the activation of stalll warning devices like the stick shaker and various other warnings , and the stress levels would be through the roof.

I think it’s the right thing personally to ground the aircraft pending further investigation and a reappraisal of the training required to operate it.

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Originally Posted by Sky High Bluebird

Yes it’s a separate process.

If the pilot makes a manual trim command the MCAS will not re-activate until there have been 5 continuous seconds without pilot trim command.

What I would say it’s one thing being able to discuss the details of a complex system in a warm room with a cup of tea.
However I can only begin to imagine the confusion and startle factor with dealing with a situation like this, throw in the likelihood of the activation of stalll warning devices like the stick shaker and various other warnings , and the stress levels would be through the roof.

I think it’s the right thing personally to ground the aircraft pending further investigation and a reappraisal of the training required to operate it.

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From a systems design point of view, if you were coming out of autopilot due to a technical problem, why would you have to go from manual control back into autopilot before you could kill the MCAS. That's confusing for me. Why not just have a big red button to disable it? But there must be a reason why they did it that way.

if the 2nd crash hadn't have happened so soon after the first, and with the amount of money at stake, would Boeing, FAA just have trashed the reputations of the Ethiopian Airways pilots and filtered in software updates during routine maintenance!!!.

Seems far fetched but the same two organisations managed to get the certification in place for an unsafe plane to take to the skies.

The official report has exonerated the pilots; they did everything required of them by Boeing. Boeing are now saying that there is a chain of events that caused the aircraft to crash while at the same time have modified their software. Given the need for the software modifications to be approved by the FAA and the individual countries Aviation authorities these aircraft will not be flying any time soon.

The preliminary report makes for sober reading.

The pilots followed the correct course of action laid down by Boeing for an MCAS fault but this was still unable to save them.
Their actions were exemplary even more so considering the experience level of the first officer.

Boeing are going to take a thumping with compensation claims from the bereaved families and rightly so.
They created an unstable aircraft , bolted on a bit of extra software on as a fix , considered nothing ,and told no one.

It’s indefensible.

Sadly I've seen footage of the last 10-20 seconds of the flight and it's the most horrendous flight I've ever seen.
The plane stalled for goodness sake. How and why would a plane need to stall?
So appallingly sad.
Great respect to the pilots who tried in vain to salvage the flight.
RIP to those who lost their lives on the Ethiopian and Indonesian flights.
My thoughts are with their loved ones.