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Comment by deepstream | Hacker News Reader

pilots should not have to fight the system. can there not be a simple button, "switch to manual"?

MCAS can be disabled, but pilots says this may not help in some situations:

> On the simulator when the stabilizer was "on a dive" at maximum angle, me and my colleagues weren't able to recover a plane.

> If you follow Boeing bulletin, but start the procedure too late, it will only make things worse. Simpler solution (in case of problems right after takeoff) is to release the flaps at least to the first position. This will disable MCAS and give you an additional time.

Source: https://denokan.livejournal.com/204046.html (Russian)

Google translate: https://translate.google.com/translate?sl=ru&tl=en&u=https%3...

MCAS can't really be disabled.

They procedure just disables the electric motor that MCAS is using to adjust the trim down. MCAS will still be sitting there sending trim down commands that get ignored.

Problem is, that electric motor is used by the manual trim adjust buttons too, so they stop functioning too. Following the procedure results in a nose down trim that pilots have to correct by manually turning the trim wheel, and it turns out the aerodynamic forces may be too strong for that procedure.

Airline safety has increased by a factor of 100 in the last 50 years, in terms of fatalities / miles travelled. Both in the past and now, far more accidents are the result of pilot error than failure of any system.

Gloryfing the good old days of pilot jocks just isn’t supported by the actual data, this incident nonewithstanding.

Isn't that orthogonal to the previous statement? The ideal situation would be to have fly-by-wire and a single hands-off button instead of HAL saying "Sorry Dave, but I cannot do that".

Of course, commercial pilots would need to have an actual interest in flying manually. The Gimli glider pilot was an enthusiastic pilot outside professional aviation.

I don't know if such an interest is still possible with modern exploitative labor practices.

I’d go beyond an “off switch” and argue that any software that’s smart enough to turn itself on without being asked needs to turn itself off if it’s obvious that the pilot is fighting against it. It’s like a classic Bayesian probability problem where the chance of a false positive is high. The software has to take into account that the stall scenario it thinks is happening is rare, and that happening followed by a pilot yanking back on the stick is vanishingly rare, accept that it was probably wrong and undo its actions.

at least you're not in charge of anything.

the plane's crashing, and you're telling the pilots (who you think might be jocks which makes you feel...even less safe?), "No don't turn it off, I have 50 years of data that says systems are safe." perfect example of doing data wrong. crazy dangerous arrogant ideas like this contributed to this tragedy.

when the systems are failing, you better hope you have some pilot jocks / true fixed wing enthusiasts at the controls, who know how to make the systems work for them, or take control if they fail, rather than some data jocks, with blinkered faith in the systems, who count cost of lives as "notwithstanding".

flyers deserve competence from their systems and data, not just from their pilots. we need pilots who have earned their capabilities, and systems that have earned their impression of reliability. current MCAS occupies a privileged position in charge of safety it has not earned.

there is a manual override but once you are fully trimmed down manually trimming up takes time and time is something you don't have much of with the plane pitching down near the ground.

If it takes too long to adjust trim to a desired position, why can’t the pilots still pitch up by pulling back on the yoke?

the control surfaces have less authority than the trim. original spec called for less mcas authority, but it was increased later without much consideration.

I see, thanks for the info.

Naive question, but is the plane actually possible to fly in "manual"?

The 737 is still mostly 1960s technology, despite all the tweaks over the years. With autopilot off, autothrottle off, and electric trim disabled, which is the situation the Ethopian pilots would have ended up in from following the checklists, all the main flight controls are entirely manual. Only the engine FADECs can't be turned off, and you wouldn't want to because modern engines rely on computised controls.

Not sure about that particular plane, but it should be. Contrary to jet fighters they are made to be aerodynamically stable.

You can fly (glide) them and even land with most systems switched off, including engines and main power.

https://www.boldmethod.com/learn-to-fly/aerodynamics/3-types...

https://en.wikipedia.org/wiki/Gimli_Glider

https://en.wikipedia.org/wiki/British_Airways_Flight_9

http://www.internationalskeptics.com/forums/showpost.php?p=1...

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