[nickjj]

In an average case (trained pilot, solid amount of experience, etc.) what is the turn around time between detecting this problem and fixing it in the air?

Like, how long does it take to determine the exact problem, spin the manual trim wheel to get to the point where you can recover from a nose dive in this case?

How does that number (in seconds I'm guessing?) translate to altitude levels?

[clon]

By regulation, when a system fails (as designed) the pilot MUST be able to recover:

- in 3 seconds when in cruise

- in 1 second when on approach

- when in the landing phase - immediately!

Such a system would be certifiable.

Most modern airliners have ~10 "memory items" that are procedures that are to be recalled and applied immediately without consulting any checklists. Runaway stabilizer is such a memory item. But first you need to recognize the issue as such..

It bears to mention that the 737 is riding on it's "grandfathered" certification status from the 60's, getting a free pass on many newer requirements that are subjected to airliners designed today. This is why it doubly makes sense for the bean counters to not design a new aircraft.

[nickjj]

That's really impressive turn around times. I wish I could debug most software errors in 3 seconds or less.

That is pretty frightening about the grandfathered rules.

I don't know much about cars but I do know they have a similar thing. Suddenly because you have a car 1 year before a point in time it can be obnoxiously loud but today it wouldn't be street legal. I almost can't believe the same thing happens with planes.

[SomeHacker44]

If you lose an engine in a small piston twin engine aircraft in the first few hundred feet after takeoff... 1 second might even be generous.

[zanderz]

have you heard that old pilot joke about twin engine aircraft? The second engine serves mainly to get you to the crash site faster.

[nradov]

The situation is actually worse with airplanes. When automobile regulations change, owners can generally continue to drive older vehicles but manufacturers can't continue to sell new vehicles approved under old rules. But with aircraft, once a type certificate is issued the manufacturer can generally continue producing it forever.

[weaksauce]

which regulations did the 737 get grandfathered into?

[toufka]

I think (please correct me if I’m wrong), the plane’s “type” is fixed, and pilots have certifications for that “type”. So theoretically the plane is simialar enough to not require completely new training if a pilot is certified to the type - this new 737 Max is grandfathered into the 737 “type”. If it were different enough, then it would be a new type. If the plane is a new type, pilots, and likely all sorts of other things, mist be retrained, and reissued.

So there’s an incentive to not just make the type backwards compatible to keep the common “type”, but also not introduce too many new features that might bring into question the grandfathered training.

This 737 Max added this new “safety feature” without telling the pilots (because it’s the “same type”). And that feature seems to have an unfortunate interaction with other systems in some circumstances.

[oliveshell]

I don’t know the specifics, but I assume the process to get changes approved to an already-certified type of aircraft (the 737 family in this case) is less rigorous than what you’d have to go through to get an entirely new type certificate.