Bloomberg story today about the 737 Max Death here. (paywall)

The FAA is signing off on these aircraft going back up into the sky to kill some people.

The news story has a couple interesting points about the MCAS.

First, “Boeing’s engineers assumed that pilots would know how to disable the motor driving down the nose and the procedure for doing so is taught to all 737 pilots. But both crews apparently became confused during the emergency and neither was able to do so.” (17th paragraph)

Does that say the procedure for turning off the MCAS system was taught to all pilots?

It looks like it does, but that’s unclear. It could be ‘Boeings engineers assumed that…the procedure for doing so is taught to all 737 pilots.’ But why would the tense and voice switch? There’s no comma before the conjunction, so one would expect the subject to remain the same. However the engineers couldn’t assume the procedure for switching off the CMAS system was taught to all pilots at the time the made the assumption. So the article reads like the author is stating ‘the procedure for doing so is taught to all 737 pilots.’

From paragraph 20, “Originally, pilots weren’t told about the system. Both the company and the FAA didn’t realize it could pose a danger.”

So they couldn’t very well have been taught to turn it off.

So what does the para 17 bit mean regarding the MCAS system? Were pilots taught how to turn it off or not?

Since two plane-loads of people died because the system wasn’t successfully turned off, I’d say not well enough.

Secondly, let’s talk aviation for second. I’m going to capitalize my specific terms. Air moving over or past a wing moves with something called the Relative Wind. The angle of the wing and this Relative Wind is the Angle of Attack. Both are big deals in aviation. If the Angle of Attack gets too high, the plane does something called Stalling and loses lift. (Note that the AoA is dependent on the Relative Wind, not the orientation of the wing with respect to the ground or something else.) The propensity of a plane to Stall, for the nose to pitch up, the maximum AoA, and etc., are all Flight Characteristics of the aircraft. Aircraft with different Flight Characteristics are different Types of aircraft. For big planes, the pilot needs a new Type Certification for each Type of aircraft s/he’s licensed to fly.

Boeing put in the CMAS because the 737 Max Death has different Flight Characteristics than a typical 737. It is more likely to Stall. The CMAS, in theory, pushes the nose of the plane down when it Stalls.

Fixes to the CMAS consist of making it easier to turn off. If the CMAS is turned off, it is not on.

But the 737 Max Death is still flying, and it has different Flight Characteristics than a regular 737, the plane the pilot has a Type Certification to fly. Once the CMAS is turned off, the pilot is no longer flying an aircraft with Flight Characteristics s/he is trained to fly. They don’t have a valid Type Certification for an aircraft with these Flight Characteristics.

I rather insist on my pilots knowing how to fly the plane we’re in all the time. That is considered optional by the FAA.

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