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Comment by bkor | Hacker News Reader

If poor training was the cause the plane shouldn't have received the same type number. So this is all still on Boeing. Boeing also specifically told these planes with the benefit that only a few hours of training would be enough.

I'm not seeing how this is beneficial for Boeing.

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Boeing seem to be pushing part of the blame to the pilot's -"Pilot error" - but this isn't due to 'lack of training' but the fact there was NO training and MCAS was not included in the manuals [1][2].

[1] https://www.seattletimes.com/business/boeing-aerospace/u-s-p...

> Jon Weaks, president of the Southwest Airlines Pilots Association, said Monday the airline and the pilots “were kept in the dark.”

“We do not like the fact that a new system was put on the aircraft and wasn’t disclosed to anyone or put in the manuals,” he said in an interview. What’s more, he noted, Boeing and the Federal Aviation Administration have now warned “that the system may not be performing as it should.”

[2] https://theaircurrent.com/aviation-safety/what-is-the-boeing...

> "Since it operates in situations where the aircraft is under relatively high g load and near stall, a pilot should never see the operation of MCAS. As such, Boeing did not include an MCAS description in its FCOM. The explainer continues: "In this case, MCAS will trim nose as designed to assist the pilot during recover, likely going unnoticed by the pilot."

There is another explanation, according to a Tuesday report in The Wall Street Journal: "One high-ranking Boeing official said the company had decided against disclosing more details to cockpit crews due to concerns about inundating average pilots with too much information - and significantly more technical data - than they needed or could digest."

I'm starting to think a plane that can't glide during a emergency because they decided to deny physics is just not a good design.

The 737 can glide as fine as a plane of that size can. The MAX didn't change anything at that and no one was denying physics. The problem was the MCAS, which as a result of a single sensor malfunction would aggressively point the nose down via the stabilizer trim.

Yep, the reason they implemented MCAS was because they popped on some larger engines, which were too close to the ground, so they moved them up and forward on the wing a bit. This gave the plane a tendency to tilt up which could cause a stall, so Boeing added some software to bring the nose down.

In both crashes, one of the two Angle of Attack sensors was incorrect. Boeing only use one AoA sensor per flight (alternating for some bewildering reason), and in this particular flight it was constantly incorrectly stating the plane was nearing a stall. So MCAS would continually kick in until the Pilot could no longer keep the plane in the air.

> "This gave the plane a tendency to tilt up which could cause a stall"

That tendency also exists on Classic and NG 737's, and is something pilots are trained to compensate for. The issue with the MAX is the degree of this tendency changed. MCAS was meant to emulate the old (less severe) behavior.

Couldn't Boeing just put in a bunch of gyroscopes into the chassis and use that as a backup AoA sensor? (I am not a pilot so I have no clue if that is reasonable)

The plane attitude (what you can sense with gyros) and angle of attack are very different things. They only coincide in level flight with no wind (the attitude is measured to the earth frame of reference (transposed by gyros) and the AoA is measured with reference to the local wind stream)

OK then why not put a couple extra AoA sensors in? I thought everything critical on airliners was supposedly redundant?

From what I've read the Max has 2 AoA sensors, but reads from only 1 at a time, and MCAS chooses that 1 sensor randomly.

Indeed, part of this story is that the MCAS system was not classified as "critial" (i.e., a system which can cause a crash if it fails). If it had been, then it would have faced additional scrutiny and they'd probably needed three AoA sensors and majority voting. Apparently the authority of the MCAS system was increased during development, with the criticality judgement based on the old smaller value.

https://www.wsj.com/articles/faa-saw-737-max-flight-control-...

That is not what is wrong with the plane.

This has very little to do with the plane's ability to glide. (A 737 glides just fine, if a bit steep for my taste).

In that particular emergency, the control surfaces prevent it from gliding. You can even have issues on a Cessna - loss of elevator is not fun.[1]

It's not about "denying physics", it's about having insufficient redundancy[2] and improper amount of control from MCAS - 3 times more than the FAA approved: [3]

No plane is 100% safe. Boeing made this one worse for the sake of saving money - the physics work out just fine, and gliding ability is not really impacted. (But I don't think it'd be a normal response - I can't imagine a pilot thinking "oh, I'm getting a stall warning with nose down at 4,000 feet, I know, I'll cut power and glide".)

[1] https://airfactsjournal.com/2018/12/elevator-failure-at-4500...

[2] https://www.seattletimes.com/business/boeing-aerospace/a-lac...

[3] https://www.seattletimes.com/business/boeing-aerospace/faile...

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