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Old 04-13-2019, 04:42 PM   #31  
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Wonder why the manual (electric) trim inputs were so minimal? My take on it is someone who reaches for the autopilot seconds after liftoff with bells going off tells me that the captain was not used to doing much hand flying. Maybe it’s a personal preference or perhaps it’s the culture of that airline. With as many lawsuits being filed over this I guarantee that aspect will be looked into.


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Old 04-13-2019, 07:19 PM   #32  
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The way the timeline is presented, without CVR dialogue, a lot is left open-ended. It will be more interesting to see the timeline set against an actual CVR transcript.

I gather from the short control wheel inputs when the stab trim motors were restored, that the crew was fighting to hold the nose up and was more focused on that than the effects of the trim switch. My impression is that there was some affirmation bias going on; the crew had already tried the electric trim and believed it wasn't working, and perhaps the very short attempt at it again was confirmation of that same bias; the belief that it wasn't working. It lends the impression that the crew gave it a quick try, then devoted all their attention to trying to hold back pressure, while the stab moved toward 0.

There's still insufficient information save for general observation, to get too specific. Some features are obvious at this point, the two most salient being that the crew didn't follow the runaway stab trim procedure, and that the crew accelerated continuously with a high power setting, compounding the problem.

MCAS aside, the AoA failure may have been causing a 4X nose down force intermittently or continuously.

The captain did call for autopilot early, and again when it disconnected; that may be a function of how they train; emergency, engage autopilot. A lot would be clearer with more detailed CVR information, as would the way the checklists were actually called out and executed, as well as the crew's perception and handling.
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Old 04-14-2019, 01:27 AM   #33  
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John Burke, while blaming 4 dead men is easy, you can’t overlook or give a pass to Boeing’s critical errors:

1. After Boeing itself said that failure of MCAS itself is a “hazard” level threat, the system by definition should never have been hooked up to only one sensor for information. By definition, a hazard level failure mode requires more than one source for information. It’s a safety requirement. Boeing failed.

2. Putting in paperwork for the feds that MCAS only travels 0.6 deg per activation, whereas reality was it travels 2.5 degrees in one go. And max travel is a little over 5 degrees on the stab trim. Boeing made the system act 4x more than what they told the feds. Boeing failure.

3. No limit on MCAS activation per occurrence of high alpha sensed. Every time the system reset with trim switches, it can run again. Unlimited cycles. 2.5 each time, 2 cycles if left unchecked will get a fully trimmed nose down. This is also a Boeing failure, when their intention was just to ease the nose down in case of high alpha due to engines being positioned higher and further forward.

4. No MCAS info passed to airline customers, nor crew. That’s a horrible failure on Boeing’s end.

For decades the saying was if it ain’t Boeing, I ain’t going. That has largely to do with the fact that Airbus has law protections, and “the computer” can get the final say and/or override the pilot. Boeing, the pilot has the final authority.


MCAS changed all that. And Boeing rolled it out horribly.

You say they should have recognized it as stab trim runaway and done the memory item for cutoff switches. Easy to say now, keep in mind they were faced first with a bad AOA sensor, a stick shaker that was on throughout, and false instrument readings. And MCAS runs the trim temporarily and stops, so it doesn’t look like a full on runaway.

Imagine if Boeing had told airlines and pilots about MCAS. If they had the proper system knowledge, maybe one pilot would have said, maybe it’s that MCAS thing, let’s get the flaps out of 0, it’ll stop. Flaps 1. And everyone lives.


The foreign regularity authorities and airlines were absolutely right to ground the MAX. The FAA let Boeing self-certify too much itself, and Boeing broke basic safety rules (see item 1-4 above).

Boeing will settle the lawsuits, just watch.
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Old 04-14-2019, 01:31 AM   #34  
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Quote:
Originally Posted by ShyGuy View Post
John Burke, while blaming 4 dead men is easy, you can’t overlook or give a pass to Boeing’s critical errors:
I haven't done either one. I deal strictly in fact.

Quote:
Originally Posted by ShyGuy View Post

Boeing will settle the lawsuits, just watch.
Which means absolutely nothing. Parties in the right settle all the time, and Boeing has the deepest pockets. Their mia-culpa(s) to date have been political and PR.
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Old 04-14-2019, 01:36 AM   #35  
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Some Boeing guy said that one cycle of MCAS putting 2.5 deg nose down, cut off switches, it would take 100 turns manually on the trim wheel to undo that one MCAS cycle. Is that true? If so, that is horrible.

No Boeing experience here, just jusmpseated numerous times. I’ve seen that trim wheel spin very fast automatically. I’d hate to see that thing run manually by a hand. No way could you be as fast?!
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Old 04-14-2019, 01:40 AM   #36  
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Another food for thought, aircraft groundings are extremely rare. But we’ve had 2 in the last 7 years and it coincides with the FAA passing more self-certification and checking into Boeing. Might be coincidence, but still the optics don’t look good. Boeing like any company wants to save costs, so of course they’ll cheapen out at certain corners. The MAX was rushed all the way through to compete with the NEO sales.
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Old 04-14-2019, 01:45 AM   #37  
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Quote:
Originally Posted by ShyGuy View Post
John Burke, while blaming 4 dead men is easy, you can’t overlook or give a pass to Boeing’s critical errors:

1. After Boeing itself said that failure of MCAS itself is a “hazard” level threat, the system by definition should never have been hooked up to only one sensor for information. By definition, a hazard level failure mode requires more than one source for information. It’s a safety requirement. Boeing failed.

2. Putting in paperwork for the feds that MCAS only travels 0.6 deg per activation, whereas reality was it travels 2.5 degrees in one go. And max travel is a little over 5 degrees on the stab trim. Boeing made the system act 4x more than what they told the feds. Boeing failure.

3. No limit on MCAS activation per occurrence of high alpha sensed. Every time the system reset with trim switches, it can run again. Unlimited cycles. 2.5 each time, 2 cycles if left unchecked will get a fully trimmed nose down. This is also a Boeing failure, when their intention was just to ease the nose down in case of high alpha due to engines being positioned higher and further forward.

4. No MCAS info passed to airline customers, nor crew. That’s a horrible failure on Boeing’s end.

For decades the saying was if it ain’t Boeing, I ain’t going. That has largely to do with the fact that Airbus has law protections, and “the computer” can get the final say and/or override the pilot. Boeing, the pilot has the final authority.


MCAS changed all that. And Boeing rolled it out horribly.

You say they should have recognized it as stab trim runaway and done the memory item for cutoff switches. Easy to say now, keep in mind they were faced first with a bad AOA sensor, a stick shaker that was on throughout, and false instrument readings. And MCAS runs the trim temporarily and stops, so it doesn’t look like a full on runaway.

Imagine if Boeing had told airlines and pilots about MCAS. If they had the proper system knowledge, maybe one pilot would have said, maybe it’s that MCAS thing, let’s get the flaps out of 0, it’ll stop. Flaps 1. And everyone lives.


The foreign regularity authorities and airlines were absolutely right to ground the MAX. The FAA let Boeing self-certify too much itself, and Boeing broke basic safety rules (see item 1-4 above).

Boeing will settle the lawsuits, just watch.
As a 727, and 747 guy who has had nothing but love for Boeing up to this point I have watched this whole situation evolve with equal parts sadness, and dismay, a little humility would have
gone a long way, the points you make are cogent and valid, way too much Monday morning quarterbacking going on, God rest and bless the crew and pax, the investigation will reveal both the why, and how, of the accidents , but Boeing’s admission of liability was telling. A sad situation.
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Old 04-15-2019, 01:32 AM   #38  
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You say they should have recognized it as stab trim runaway and done the memory item for cutoff switches. Easy to say now, keep in mind they were faced first with a bad AOA sensor, a stick shaker that was on throughout, and false instrument readings. And MCAS runs the trim temporarily and stops, so it doesn’t look like a full on runaway.
Incorrect on all counts. You haven't read the report, have you?

I don't say that the crew should have recognized it. I don't guess. The crew DID recognize it, and did the "memory item for the cutoff switches." Did you not know this?

The crew verbalized it. The crew cut off stab trim. The crew verbalized the failed AoA vane and recognized it.

The crew also restored stab trim when the procedure specifically states that they should not. This procedure is not new: it's been the same for decades.

Stab trim isn't quiet. It's noisy. It's hard to miss; two big wheels, each with a big white stripe in plain sight, next to the thigh. If the autopilot isn't engaged and the pilot isn't trimming and trim is running...fairly obvious that it's uncommanded, and one can either watch it go, or stop it. The crew stopped it, then enabled it again.

Piloting 101: when a problem occurs, keep configuration and speed, especially when the problem gets worse as one changes airspeed. The crew continued to accelerate well outside the performance envelope, and aircraft limitations, as the downward pitching moment continued to increase.

Given that existing Boeing control feel is applied at a force four times normal approaching a high alpha condition (not just in the max), the issue of MCAS is a non-starter, and a nose-down force in response to an AoA error could occur in other 737's outside the Max line; this isn't new and isn't obscure, and is well known.

Not all cockpits are occupied by pilots. Pilot fly the airplane back. Passengers observe the crash.
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Old 08-27-2019, 12:33 AM   #39  
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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.

What about this part.
“From 05:40:42 to 05:43:11 (about two and a half minutes), the stabilizer position gradually moved in the AND direction from 2.3 units to 2.1 units. During this time, aft force was applied to the control columns which remained aft of neutral position. The left indicated airspeed increased from approximately 305 kt to approximately 340 kt (VMO). The right indicated airspeed was approximately 20-25”

Is the 2.3 and 2.1 from the manual trim? Also. What are the chances of MCAS still causing a runaway after the system has been cut out? If you know that is.

Appreciate your time, John!
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Old 08-27-2019, 08:02 AM   #40  
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Organizational Designation Authorization, ODA...
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