Well that's pretty open and shut.

It looks like you have to disable the MCAS prior to it reaching the 2.5 pitch down, obviously manual trimming may become extremely difficult with aerodynamic forces while trying to maintain altitude that low.

Love when pilots take every headline and everything the news says as fact...

Read the article again... The never say which direction they were trimming!! Inexperienced FO remember.

They wont be able to cover this up forever.


For those that can't keep up, they manually trimmed the nose down instead of up.

Really? I can't access the rest of the article.

?
..........

We are just going to have to wait for the final report. They are purposefully being vague.

Huh? The article says that they were trying to manually trim the plane to get the nose up and couldn’t do it so they turned the trim cutoff switches back on and that’s when the final nose down input occurred.


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Ethiopian 737 MAX 8 crash
 

Double post...

Yeah, the procedure would require you to release back pressure to manually trim the aircraft back to neutral. That might be impossible at that altitude.

That's weird, my conclusion was the crew screwed up. So were you trying to reinforce that or were you trying to tell me my conclusion was wrong while arriving at the same conclusion?

Still a stupid system design though.

Isn't it that on all the 737s you can't manually trim nose up past a certain point unless you haul back then release elevator pressure?
Either way this is looking really bad for Boeing and the MAX.

If it's anything like the 72 then past a certain point the aerodymanic load is so strong that you need both guys to haul back on the trim wheels, or have the FE pedal backwards.

The Max 10 won't have MCAS as the new gear system provides enough engine clearance. I wonder if that can be adapted to the 8/9, that would clear the political red tape.

I was quoting the other guy. He’s saying that the article is wrong and the guys trimmed the wrong direction. I have a hard time believing this and I haven’t read it anywhere.


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You haven't read it anywhere because that part was not leaked. Also, you have a hard time believing an FO with only a few hundred hours couldn't trim the wrong way?

In other news.

https://www.thestreet.com/markets/bo...7pWmPT5MiF7v0s

No, I have a hard time believing some anonymous person on the internet saying the FO trimmed the wrong way. But who knows, maybe you’re right, we will know when the official report comes out.


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It's ok, nobody's perfect.

It's looking really bad for any 737 or 727. That innocuous warning in all of our manuals was thought to be an easily remedied thing. It seems luck and some good training in some hands has kept it from happening in both fleets until now except for a few posts in these various threads that explain the phenomenon. I was a FE on an EAL sim where the front end trimmed down too much for an emergency descent and when the speed built up we crashed because back stick didn't work. Sim pilot said oh that's trim lockout so we thought it was a sim problem not an A/C problem.

Wow. Reading that preliminary report, it certainly does appear the manual trim was applied in the wrong direction.

There is no indication that the pilots even attempted to manually trim the aircraft except for a brief 10 second period (which started about a minute after they cutout the electric system), after which they apparently gave up.

One would think, with a flight control issue, airspeed would have stayed in the cross-check. I'm sure trying to deal with this while accelerating to VMO didn't make it easier. From the N1 and airspeed plot on the FDR, it pretty much looks like the throttles were locked forward until about the last 15 seconds of flight.

I noticed a sentence about the N1 stabilized at 94% (during takeoff roll). From this point for most of the flight the N1 reference remained there and the throttles didn’t move.

I don’t see any specific mention of the auto throttles being used or if/when they disengaged. I would expect some movement if they were engaged, but if not did the crew forget that they needed to control thrust on their own?




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Read page 11, at the "From 05:40:42 to 05:43:11" mark. It appears they were manually trimming over about a 2 minute period.

Checklist in the report says turn them off. Don’t know if they ran the whole thing or just the initial stab cut-out action.
777 stabilizer checklist (memory items) says do not exceed current airspeed once cut-out switches are off. The 737 checklist in the report doesn’t mention airspeed. But if trim and stick forces are a problem, more airspeed is definitely not going to help.

I did see that, but the overall movement was so little, it looked to me like it was the position indicator itself fluctuating slightly.

I also see that they turned the autopilot on, even with the stick shaker going off.

Better articles out. They couldn’t move the wheel due to aerodynamic forces.

Not looking good for the Max...


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Wonder how well one can manually move the trim wheel in 737NG while at Vmo


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Read the data. No they didn't. Not in any measurable meaningful way anyway.

Time to use the “lemon law” and return those POS to Boeing.

Isn't that a speed on elevator thrust mode on the Boeing? So AT would only command climb thrust, and it will overspeed if you can't get the plane to climb.

2.3 to 2.1 is measurable. .2 to be exact.

Why were there electric trim inputs before placing the switches in cutout so short and so few? If you have pressure on the flight controls trim the pressure off. Hold the trim. They used small quick inputs then quit. All the time the throttles are at T/O Trust.

They sure had time to talk on the radio a lot during this but not to trim?

Seems to be the case after moving the cutout switches back to normal as well. Only two quick clicks and then nothing, even after the last MCAS command. I also notice that their altitude appears to be under control, even slowly increasing, until they turned the electricity back on.

There are quite a lot of things going on in that cockpit. Even after cutting out the trims, they were still only barely able to control the airplane. Per the FO's comment, the manual trim wasn't working. Wouldn't surprise me if you can't move it to the other direction at those speeds. Investigation will reveal more about this.

Main reason will be pilot error - they let the trim run away a bit too far, and they let their speed climb way too high. But the fact is - Boeing's design allowed a single failure degrade the handling to a point where it clearly was very, very difficult to keep the plane under control. Under Part 25, this should be "extremely improbable" - defined as 1 event in 1 billion flight hours, or never in the expected life of the whole fleet. Clearly that requirement is not fulfilled with the 737 MAX.

To slightly adjust an old saying, Boeing put the pilots in a position, where only superior skills could have saved them.

Some thoughts on this?

https://www.seattletimes.com/busines...vvkO0T60ENyldE

Checking your history seems you and your family have quite a vested interest in Boeing, that explains why you're slamming and slandering these dead pilots. Really in poor taste and lacks any kind of professional character.

Proactively trimming off control forces and basic power/airspeed management don't sound like advanced level skills.


It sounds like these guys were in over their heads from the start. They activated the autopilot even with the stick shaker active. The overspeed clackers start going off and they're still messing with the guidance panel and talking to ATC. Timid to non-existent effort to keep the trim under control. Zero power management...

Startle Response degrades performance significantly. The loud noise of the shaker constantly on, will also significantly degrade task performance. They may not have even heard the clacker.

I’m not sure what you mean by speed on elevator thrust mode. The report says at 1,000 feet the autopilot was engaged (on the 3rd attempt) and 20 seconds later level change at 238kts was selected. This climb mode the auto throttle will hold the N1 limit and the auto pilot will pitch to maintain airspeed. 18 seconds later the autopilot is off and MCAS is engaged.
But yes good point that it will overspeed the aircraft with the nose now coming down. But that still doesn’t relieve the crew from being pilots and not dangerously letting the speed run away.


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