Thread by @soychicka

I was waiting to see someone say @ActingSecDef made redundant safety equipment an upgrade, given it was an affordance for an affordance for a design flaw he in the 737 Max 8 when he was in charge of the Airplane Program at Boeing...

nytimes.com/2019/03/21/bus…

Here's the problem:

each aircraft had 2 sensors that detected 'angle of attack' - essentially, the angle between the direction the plane is traveling in and the 'chord' of the wing - kind of like the midline.

How wings work: they're curved on top, and not as much on the bottom, which makes them longer on top

when you move the wing through the air, the air on top has to go faster to get over the same amount of wing as the air below, and that makes the pressure of the air above lower.

when the air pressure above the wing is lower than the air pressure below, you get lift: think of it kind of like a vacuum sucking the wing up.

when that lift exceeds the weight of the plane, the plane flies.

now, if this angle gets too steep, air will stop flowing smoothly over the surface of the wing, spiraling off into eddies (aka non-laminar flow)...

that means the difference in pressure between above and below the wing is smaller, less lift, and that can lead the plane to fall

How exactly this works varies with wing shape, plane weight, airspeed, etc, so the angle of attack you want changes over time - it makes sense to have a computer handle those calculations.

Problem with the 737 Max was that the new engines were larger and more powerful, so they would be closer to the ground and more likely to suck in debris, be damaged if the plane went off the runway (it happens, esp in snow - trust me), etc. when taxi-ing...

So to keep the plane low to the ground so it can serve smaller airports, the designers moved the engine position on the wing - changing the design of the pylon they're mounted so that they jut out in front of the wing.

And that changes how the plane behaves, so that the aircraft is more likely to have a nose-up attitude (aka a larger angle of attack) that pilots have to compensate for, by either pointing the nose downward / increasing airspeed

And that's where MCAS (above) comes in - it takes over and automates that adjustment.

But Boeing was only using readings from one of the two onboard sensors, unless you upgraded.

And you also had to upgrade to get a warning.

And that's some mobbed up protection racket shit.

Because

a) all aircraft features require redundancy in design - ie failsafes or backups in case one fails - because if something breaks in flight, you'll fall out of the sky and most likely die.

b) this isn't someone buying a personal car and upgrading or activating a software-based feature.

Passengers don't have the option of checking the configuration of every aircraft they fly on.

Passengers have the right to assume the same minimum safety standards when they fly on any given aircraft model in any nation; aircraft with different sets of safety features need to have different model numbers.

But, back on track...

the decision to make this safety feature an OPTION was ultimately the responsibility of one man at the top of the program:

@ActingSecDef Pat Shanahan, VP of Airplane Programs during B737 MAX R&D