Originally Posted by JohnBurke

You understand neither the report, nor the aircraft, nor the system.

The control wheel nose-up trim attempt at 5:43:11 occurred as pilot-action. This is very significant, because at 5:40:35, nearly three minutes prior, the crew had already used the stab trim cutoff switches. Once the stab trim cutoff switches have been moved to the cutoff position, stab trim may not e re-engaged.

The recording of pilot electric trim input at 5:43:11, with subsequent increase from 2.1 to 2.3 units, is evidence that the crew re-engaged the pitch trim motors.

The pitch trim then moved nose down from 2.3 units to 1.0 unit. THIS WOULD NOT HAVE OCCURRED IF THE CREW HAD NOT RE-ESTABLISHED PITCH TRIM MOTOR CAPABILITY BY RESTORING THE POSITION OF THE STAB TRIM SWITCHES.

Read that again in case you didn't get it.

Once the stab trim motors have been cut off, the stab trim motor cutoff switches must NOT be restored. The crew restored them, thus enabling the trim to run away again.

At the same time, they continued to make the trim force problem WORSE by accelerating.



You don't know that.

Clearly they had one mission with unwanted trim motion: cutoff the stab trim motors and leave them cutoff. That singular action would have prevented this mishap, had they been left in the cutoff position, and had the crew not continued to accelerate.

As stated previously, it's possible to make a salvageable situation unsalvagable, and that's exactly what the crew did.



It is your interpretation. It's wrong.

The captain made several requests of the F/O. Trim with me. Pitch with me. Pitch with me.

The crew didn't trim in the wrong direction. The issue of a "feedback loop" is irrelevant. The controls were heavy nose down, due to an out of trim condition. They made an attempt to restore it, with minor success, but the let the trim run nose down again. They attempted to retrim, cut it off, and would have been required to maintain back pressure based on an out of trim condition, but it was manageable and flyable at that point. Only two things could have made it worse: re-engage the stab trim motors, and increase airspeed.

The crew did both. And it killed them.



Not at all.

The 737 Max didn't misfire, nor was it poorly designed. First and foremost, a sensor failure occurred: the crew recognized the sensor failure, and already had notification in their flight manual of the potential complications of an AoA failure; this notification had been in their flight manuals for several months.

The procedure for unwanted stab trim, regardless of the cause, is the same. It's fully applicable here. It's not new. It's been in play for decades. It's spelled out in the report, in case you don't know it. The single most important element of that procedure is a memory item: stab trim cutout switches CUTOUT.

Once those switches are placed in cutout, they are not to be restored. The crew restored stab trim operation, knowing that stab trim motion was nose down, and that it was uncommanded.

This was not a faulty design or aircraft: this was a faulty pilot action, and a fatal one. Accelerating beyond Vmo in the aircraft sealed it. No chance of recovery, and they rode it into the ground with the overspeed clackers going off the entire time.

No, if a man robs a liquor store with a S&W handgun and shoots the clerk, it doesn't matter if he fumbled the safety at the time, and it doesn't really matter if the pistol has a mechanical problem and discharges without his finger on the trigger: it's his action, robbing that store, that killed the clerk, and it won't help him a bit to try to pawn it off on the pistol.

A pilot in command has the ultimate responsibility for the safe outcome of the flight. He knows that malfunctions can occur in the aircraft; it's quite literally all we train to do, is handle them. Ultimately, however, our first job is to fly the aircraft, and we have procedures to do this; the procedure was violated in this case, and it was that violation that allowed the trim to decrease further nose down, and on top of that, the crew allowed the aircraft to continue to accelerate, thus increasing the nose-down force as the flight diverged farther and farther from it's trimmed speed. Additionally, leaving power in and flying it beyond it's maximum operating speed, entirely out of the operating envelope, eventually prevented any possibility of recovery.

If you want to pick nits about a pistol analogy, the pilots were robbing the liquor store, and held the pistol on the clerk. They engaged the safety (stab trim cutoff switches), and at that stage, there was no chance of shooting the clerk...not until they disengaged the safety (restored the stab trim motors), and set the ball rolling. Everything they did thereafter only sealed the fate, and that's pilot action, not a manufacturer failure.