https://www.cnn.com/2019/04/07/politics/boeing-aviation-737-max-aftereffects/index.html

 

As I suspected right from day one, the Max was an accident waiting to happen. Boeing and the FAA tried to cover it up, but couldn't. Blaming the pilots didn't work. 

Hello,

uninformed observer here again.

Would it not be possible to add power assistance that is only activated when force is applied in the cockpit to the trim wheel

and all other trim devices are disabled, just as in vehicle power steering?

It would only need to help the turning of the wheel.

Secondly, if it proves impossible to move the trim wheel manually because of the forces acting on it and the ground is rapidly approaching,

does switching the trim power back on seem less of a mistake than a last ditch attempt in an impossible situation?

Edited April 7, 20197 yr by Reader

31 minutes ago, KevinAu said:

I don’t know how the car power steering is relevant here. You were the one who first brought up that power steering had existed for 40+ years, whatever that had to do with this in your mind.

Now now, lets not be rude. Let me explain more clearly.

I think in all flight envelopes there should be a way to trim the aircraft. The roller coaster tecnhique Boeing suggest should not be acceptable IMO.

The certification should state a single (female) pilot must be able to manually trim the plane (for any trim runaway scenario not just MCAS).

Power assistance like in cars (just one suggestion) would have avoided these crashes, and it could be powered in the cockpit only as Reader suggested above.  

Second point the 737NG STAB TRIM CUTOUT switches worked differently to the MAX. Another point of confusion for a crew that only had 1 hour of type conversion training.

From https://www.satcom.guru/2019/04/stabilizer-trim-loads-and-range.html. 1 switch disabled the MAIN ELEC (Trim switches) and the other disabled the Autopilot.

For some reason they changed this (probably MCAS) in the MAX so that ELEC TRIM is disabled always, meaning if you want to disable MCAS you have no Electric TRIM and have to use manual trim! 

The NG seems a better design. You just flick the Autopilot STAB TRIM CUTOUT switch and now you have complete without needing to manually trim. 

The reason I brought up cars power steering was to point out that this is a simple and standard technology. It seems strange that the newest 737 requires a both pilots full force to trim manually.

19 minutes ago, Reader said:

Secondly, if it proves impossible to move the trim wheel manually because of the forces acting on it and the ground is rapidly approaching,

does switching the trim power back on seem less of a mistake than a last ditch attempt in an impossible situation?

Exactly. 

Edited April 7, 20197 yr by DellyPilot

14 minutes ago, DellyPilot said:

Several points. The Captain is using all his force to pull back on the column while the FO is struggling to crank the trim wheel. The Captain then applies Trim up switch (several times) and the stabiliser barely moves, perhaps because the motor is disabled or perhaps because it is fighting aero forces too. Perhaps in the very stressful situation with one hand the captain flicks the STAB TRIM switches to on hoping to help trim back up so he can relax control pressure.

This is just one hypothesis but you have already stated this is his biggest error. I find that hard to comprehend from another pilot but fair enough we should consider all the mistakes the crew made... but the idea that another crew would have easily coped with it is absurd.

Slapped wrist, yep, definite error if it was one of them should have been announced, despite the dire situation

This is an interesting one, so at what point would you have identified (without hindsight) that this was runaway trim scenario.

So as a recap at 05:40:05 the first MCAS even happens and the planes climb is arrested. The stick shaker is still sounding and the DONT SINK WARNING sounds 10 seconds later. The Captain says trim up and then 15 seconds later at 05:40:35 the FO announces STAB TRIM CUT OUT.

Ok, really? So you are saying they should have realised straight away at 5:40:15 when the plane stopped climbing that MCAS had triggered and they were in TRIM RUNAWAY situation? This is an incredible assertion IMO.

Yep, this was the final nail in the coffin and pasting from my above post these are my thoughts:

Just a couple of other points on why maybe they didn't reduce power, Bole airfield is 7657ft and Cpt PFD was reading lower IAS, combined with the mentally overwhelming Sshaker blaring + IAS DISAGREE (are we stalling?), then the plane is pitching forward but reducing thrust you feel could exacerbate pitch forward movement.. easy to judge it now.. but only 40 seconds to weigh this all up before you're in a flying coffin. Just very sad.

I am not enraged and there is no no hostility at all, you are banging the crew error drum for days now and as a internet contrarian you're getting some nice forum action. Fine, I get how it works.  

And yes all accident reports have to consider the actions of the crew, its a factor in every crash. But as a pilot a little bit of empathy for the situation they faced is in order, to me so far at least the errors they made are all a product of the inadequate training and poor design of multiple systems within the aircraft.

Well, restoring the trim power and not coordinating it was huge. That is what killed them. They were still climbing before that. They may not have been able to move the trim wheel, but they still had enough authority to keep from nose diving. A crash was not sealed until this. Don’t brush that one off. It was a violation of the procedure they were doing and it was a configuration change that happened without any coordination. Those are big no no’s in my training. And it also killed them. Did I say that already?

Again, why I think that was the FO that did that. Because if it was the captain who did it with one hand in order to get his yoke trim back, you would think that he would then immediately run the trim way the heck back in the nose up direction. But there isn’t any such command. Just a small blip that the report does not identify from which side. Which leads to the deduction that it was the FO who did that after saying the manual trim isn’t working. Then he blips the trim on his yoke to give it a try, but since he wasn’t the one flying, doesn’t put in a more continuous command. But then he fails to tell the captain that he has the yoke trim working. So the captain never puts in a trim up command. While at the same time, the mcas finds the trim working again and its fourth command drives the stab all the way down and kills them.

They weren’t in a coffin until the trim was turned back on. And if it was the fo who flipped it back on, the nail wasn’t driven home until the fo failed to tell the captain he could trim up.

6 minutes ago, KevinAu said:

Well, restoring the trim power and not coordinating it was huge. That is what killed them. They were still climbing before that. They may not have been able to move the trim wheel, but they still had enough authority to keep from nose diving. A crash was not sealed until this. Don’t brush that one off. It was a violation of the procedure they were doing and it was a configuration change that happened without any coordination. Those are big no no’s in my training. And it also killed them. Did I say that already?

Again, why I think that was the FO that did that. Because if it was the captain who did it with one hand in order to get his yoke trim back, you would think that he would then immediately run the trim way the heck back in the nose up direction. But there isn’t any such command. Just a small blip that the report does not identify from which side. Which leads to the deduction that it was the FO who did that after saying the manual trim isn’t working. Then he blips the trim on his yoke to give it a try, but since he wasn’t the one flying, doesn’t put in a more continuous command. But then he fails to tell the captain that he has the yoke trim working. So the captain never puts in a trim up command. While at the same time, the mcas finds the trim working again and its fourth command drives the stab all the way down and kills them.

They weren’t in a coffin until the trim was turned back on. And if it was the fo who flipped it back on, the nail wasn’t driven home until the fo failed to tell the captain he could trim up.

You should get a job with Boeing. You would straighten all this out..😉

Why not just turn on the right autopilot rather than the left? 

12 minutes ago, DellyPilot said:

Now now, lets not be rude. Let me explain more clearly.

I think in all flight envelopes there should be a way to trim the aircraft. The roller coaster tecnhique Boeing suggest should not be acceptable IMO.

The certification should state a single (female) pilot must be able to manually trim the plane (for any trim runaway scenario not just MCAS).

Power assistance like in cars (just one suggestion) would have avoided these crashes, and it could be powered in the cockpit only as Reader suggested above.  

Second point the 737NG STAB TRIM CUTOUT switches worked differently to the MAX. Another point of confusion for a crew that only had 1 hour of type conversion training.

From https://www.satcom.guru/2019/04/stabilizer-trim-loads-and-range.html. 1 switch disabled the MAIN ELEC (Trim switches) and the other disabled the Autopilot.

For some reason they changed this (probably MCAS) in the MAX so that ELEC TRIM is disabled always, meaning if you want to disable MCAS you have no Electric TRIM and have to use manual trim! 

The NG seems a better design. You just flick the Autopilot STAB TRIM CUTOUT switch and now you have complete without needing to manually trim. 

The reason I brought up cars power steering was to point out that this is a simple and standard technology. It seems strange that the newest 737 requires a both pilots full force to trim manually.

Exactly. 

Yes, let’s not be rude or condescending, so maybe we should can the comments about one of us getting off on internet contrarian action.

Certification would’ve and should’ve are fine for the boeing 797.  I have no opinion one way or another about what the certification rules should. They are what they are. This plane was certified under the rules it was certified under. Believe it or not, that manual trim is a luxury, there are new planes out there with absolutely no manual reversion once the trim cutouts are selected. They are stuck there for the rest of the flight however long or short that may be. Maybe that should not be allowed anymore? Who knows? I certainly don’t, I just fly them.

The mistakes and risks of the mcas design are known and understood. Nothing really to discuss at this point in the thread as far as I can tell. The only thing left in the chain that can affect the outcome are the pilot actions, which should not be verboten to analyze, because it is all that stands between a landing and a crash. Maybe the ng system is better. But the point I am making about going against a procedure and not verbalising it are examples of lessons we can take away in basic airmanship discipline or lack thereof that apply to any pilot in any plane in any emergency.

12 minutes ago, HighBypass said:

Why not just turn on the right autopilot rather than the left? 

How would they have known to do that?

No idea Kevin, but the preliminary report had an entry where the Left autopilot was turned on briefly (which to this layman implies that there is a separate Right autopilot). Wasn't the left AOA vane giving all the garbage data assuming the crew knew that the left vane was garbage of course.Would a right autopilot take data from the right vane among other inputs? That's why I was asking. 

15 minutes ago, Bobsk8 said:

You should get a job with Boeing. You would straighten all this out..😉

Well, my little brother did. And I was his primary flight instructor. But he left boeing after the 787 and 747-8, just before the max. He jumped over to scaled to help develop the stratolaunch carrier.  Yes, I think he would have saved them. He is a cognitive science expert and it was his job to think through exactly these kinds of failures and how pilots would perceive them and build procedures. Boeing lost a lot of engineering talent after the 787.

6 minutes ago, HighBypass said:

No idea Kevin, but the preliminary report had an entry where the Left autopilot was turned on briefly (which to this layman implies that there is a separate Right autopilot). Wasn't the left AOA vane giving all the garbage data assuming the crew knew that the left vane was garbage of course.Would a right autopilot take data from the right vane among other inputs? That's why I was asking. 

I don’t think ethiopean had the aoa warning option. All they would have known was that there was a disagree. I doubt they would have known which side was good at that point.

4 minutes ago, KevinAu said:

I don’t think ethiopean had the aoa warning option. All they would have known was that there was a disagree. I doubt they would have known which side was good at that point.

Nothing like having a single point failure item in one of today's latest passenger aircraft. It goes, and the aircraft turns into a lawn dart,.

Kevin - thank you sir! A disagree would not tell anyone which side was bad, only that there was a ..disagree..  This leads me to a further question.. IF the crew had known which side was bad.. I wonder IF they had turned on the other autopilot then it would have given them more time? Of course this is all "WHAT IF"  from the comfort of my pc chair at ground level with not even my wife screaming any warnings at me, let alone my imminent demise staring me in the face..

Thanks for your time gents (apologies if there are any ladies in this discussion). Here's one layman who appreciates the discussion so far.

This is a brilliant topic.  The best we've had for months, if not years. The techinal knowledge is fantastic. 

As I've said before It will be very interesting to see how long it's grounded for and whether law suits start happening.  

Once it is working again, every check in agent in the world is going to get asked 500 times a day 'is the plane one of those max planes that crashed' 

 

 

2 hours ago, KevinAu said:

I don’t think ethiopean had the aoa warning option. All they would have known was that there was a disagree. I doubt they would have known which side was good at that point.

The captain had the stick shaker on his side. Might have been a clue?