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Old 5th Apr 2019, 13:59
  #3314 (permalink)  
positiverate20
 
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Originally Posted by JesusonAHarley
I usually don't contribute anything to a discussion, preferring to listen more to what everyone has to say. This is reflected in my posts on here too, which are non-existent. However, I have been following this thread very keenly and am very grateful to all the amazing insights and points of view provided. I'm a NG/Max driver and coincidentally, flew a Max on both the crash days.

Generally, my attitude towards any incident / accident is "They should have done this. But, I wasn't in that hot seat. Maybe I would've done the same". However, I've been struggling a lot trying to get that attitude and the posts on here have helped. Especially the ones which have been downright condescending of the operating crew. They have helped me get my perspective.

One thing that I have noticed in the preliminary report of the ET is that the pilot ANU stopped at exactly 2.3 units on three separate occasions. The first one was a shallow pick-up after the first MCAS activation. The second one was a more agressive pick-up immediately following the second MCAS activation, suggesting that the pilot(s) now knew what they were dealing with. As soon as the ANU stopped at 2.3 units, FO asked if he should cut-off the stab trim. The third was when they, presumably, reactivated the stab-trim to get some leverage with the electric trim and ended up with short bursts, instead of a long ANU activation.

With discounts given to adrenalin not allowing you to feel the AND for the first one and coincidence being the second, the third ANU also stopping at 2.3, suggests there was something else at play and not merely pilots not knowing how much to trim. The clue is provided in the timing of the FO suggestion for stab-trim cut-off.

Or am I reading too much?
I understand where you are coming from. I, too, was appalled at the attitude of some on here- stating the pilots must have been wrong based on where they came from. I also hypothesised a very similar scenario on 13th March- post 1171- all that I hadn't mentioned was the difficulty in turning the trim wheel at higher speeds, but I'd assumed that would be obvious if anyone looked at the indicated airspeed from the ADS-B data that was available at the time! (Put your hand out the window of your car when you're driving at 60mph/100kmh- it's a lot easier to move back and forward than at 100mph/160kmh!) The roller coaster movement I had never heard of before- and not sure if this would have been an option on this flight given the speeds and altitudes involved.

Mentour pilot's video was fantastic, it was uploaded prior to the publication of the preliminary report, it's a shame he has removed it. He also stated the reason for doing the test was because too many people instantly blamed the pilots just because of the geographic location of where they worked!

I also have a couple of queries about the data:

All the electric trim inputs from the pilot are short throughout apart from one...:

At 05:40:27 the Captain advised the First-Officer to trim up with him.
On this occasion, the trim moved 1.9 units ANU over a period of 8 or 9 seconds! This is the only occasion in the entire flight where the pilots were able to command ANU trim for any longer than 2-3 seconds. Possibly your point and my point are related to the 2.3 unit mark. Otherwise, is there some reason that the Captain's trim switches were compromised? It is the only time in the transcript where the Captain requested the FO to trim up with him. With the Captain's stick-shaker activated etc. would this possibly cause any complication to his trim commands being tripped out so soon each time? Is there another hidden 'safety' system that limits the pilot trimming up when stick-shaker is activated? Or is it simply just a case of the motor not being able to operate due to the increased forces at the given airspeed (when considering the blips later on)?






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