JohnBurke

This isn't a tangent. This IS the crux of the matter. This isn't a failure on the part of Boeing: this is crew action, and it is at the heart of what ultimately happened.

Control feel in response to control deflection, trim, etc, is an artificial simulation that Boeing does in all their products. If you've ever tried to operate a Boeing aircraft without artificial feel, it's really tough. It's a very uncomfortable, uneasy feeling, and it's very easy to over control.

That heaviness on the controls, that feeling of "holding the nose up" with having to muscle around the back pressure, is a simulation for the benefit of the pilot, through the feel and centering unit.

Another separate potential is that of the elevator feel shift module, which applies a feel force four times normal in the nose-down direction: this is an artificial input that makes the controls feel heavier and is done specifically to prevent the crew from raising the nose deeper into a stall. It activates at low speeds (high AoA), and requires that stick shaker already be active and AoA 8-11 degrees beyond the icing biased range. Aside from an AoA indication (or indirect indication, and the crew verbalized an awareness), there is no cockpit indication for EFSM activation in the 737, other than the actual control feel.

Note that per AD 2018-23-51, Runaway Stabilizer, the following indications are expected in the event of a single AoA failure:
Continuous or intermittant stick shaker on the affected side (only)
Minimum speed bar (red/black) on the affected side only
Increasing nose-down control forces
IAS DISAGREE alert
ALT DISAGREE alert
AOA DISAGREE alert (where installed)
FEEL DIFF PRESS light
Autopilot may disengage
Autopilot may not be able to be engaged

Note that these things occurred and were verbalized by the crew.

The AD, of which both crew were aware and which had been in their manual for several months, includes the following clear counsel:

"In the event an uncommanded nose-down stabilizer trim is experienced on the 737-8/-9, in conjunction with one or more of the effects listed, do the existing AFM. Runaway Stabilizer Procedure, ensuring that the STAB TRIM CUTOUT switches are set to CUTOUT and stay in the CUTOUT position for the remainder of the flight."

Note also that at high speeds, particularly edging out of the envelope, compressibility, tuck, and mach trim issues may come into play, further altering the control and handling of the aircraft. The the time of impact, the aircraft speed was far outside the envelope for the 737, and features to address this may have been working against the crew, or unavailable to the crew, having taken the aircraft to that point.

It can't be over looked either that these events were taking place at 14,000' on a VFR morning.

Regarding feel force (the artificial feel that makes the pilot think he's experiencing aerodynamic feedback through the cockpit flight controls, when really he isn't); it's a sliding scale that increases hydraulic pressure and thus feel force, as airspeed increases. The amount of force required to counter the feel force increases at faster speeds.

While a great deal of publicity focuses on MCAS, it's well to note that since the introduction of the 737NG and changes made to the system at that time, a system perception of a stall warning (AoA based) will cause nose down control feel forces and stab trim changes which can drive the stab trim to zero if necessary, and at the same time increase control column feel force 4X in the nose down direction to discourage pilots from pulling back the control column when AoA reduction is needed. In all cases, the stab trim can be stopped with electric control wheel switches, manual trim wheel intervention, or stab trim cutoff switches, and for this reason, reactivation of the stab trim (by restoring the stab trim cutoff switch position) is prohibited.

Xjrstreetcar

All the jury will hear is that these flights would have landed safely if these crews had been flying an 800 series with this failure. The difference is the Max no matter if it is established that a minimum required standard of airmanship was met or not..

JohnBurke

Not remotely the case.

Not with the JATR convened and every member-nation involved.

Civil suits are another matter, and not really relevant to the discussion.

Xjrstreetcar

You don't think that the likelihood that this failure on any other type variant would have ended up differently is relevant? Certainly relevant to establishing a new type or not...

JohnBurke

You just invoked civil suits.

Now you want to talk about actual safety.

The two aren't the same. Civil suits are irrelevant.

Any other "variant?" Have you read this thread? Do you know anything about the aircraft? Do you understand the system or the procedure? Do you know the procedure applies across the board to the rest of the 737 fleet?

Xjrstreetcar

I must have missed that the groundings and coming modifications go beyond the Max..

JohnBurke

You're a troll, aren't you?

Your previous post wanted to talk about irrelevant civil law suits. Your next post changed tack and wanted to talk about the importance of discussing Boeing malfunctions that go beyond the 737 Max, and now you're changing again to argue that this should be confined to the 737 Max as nothing else has been grounded.

Are you on drugs?

You are on the ignore list now. Good place, too.

Xjrstreetcar

Was that dude some sort of lobbyist? Hard to determine given that his post history is hidden..Didn't seem to handle cognitive dissonance well..

WutFace

I'm getting that vibe. He's very active about this very particular topic, and adamantly defending the MAX day after day.

I'm starting to think he's part of the social media PR.

JohnBurke

You think I'm defending the 737 Max, do you?

Reading comprehension a bit low for you, then?

Try getting informed about the crash, then talk.