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Sad: Atlas 767F down near Houston

Started by Jeroen Hoppenbrouwers, Sun, 24 Feb 2019 12:25

John H Watson

QuoteInterestingly, to get this trimming inhibit system to work, the columns have to be moved in the same direction.

Just to clarify... I meant that both columns have to be moved in the same direction as each other (in the opposite direction to the column switch trimming) to stop the trimming.

I was talking about having one pilot pushing and other pilot pulling (i.e. split elevator operation) with one pilot trimmng.


emerydc8

Sorry, I misunderstood what you were saying there. But with regard to the example of the runaway stab trim, I don't know how else the system and the QRH would work. I never tried the stab cutout check by trimming in the same direction as elevator movement -- only in the opposite direction. But if the cutout system inhibited the stab from moving when trimming in the same direction (yoke full forward and trimming nose down at the same time), then how would you ever get the stab to move in this case? The cutout feature wouldn't allow it. I guess you could release the forward pressure on the yoke and try to get the trim moved forward, but the QRH doesn't mention this technique. Maybe this is just another mystery system of Boeing's.

John H Watson

I still think I'm not explaining myself properly.

If, say, the captain was pushing the nose down, but trimming nose up, and the F/O wasn't doing anything, the stabiliser would not run. Both column cutout switches would be open circuit. If the F/O then pushed hard in the wrong direction, the captain's wrong trim input would then activate, assisting the F/O's column input.

This scenario wouldn't happen in real life because you would need both pilots to do silly things. The 4 column cutout switches are only there for redundancy.


Roddez

Quote from: John H Watson on Sun, 24 Mar 2019 14:37
This scenario wouldn't happen in real life because you would need both pilots to do silly things.

Sadly John, as attested to by many accident and incident reports, this happens far more than we like to see...

Rod
Rodney Redwin
YSSY
www.simulatorsolutions.com.au

John H Watson

#84
There seems to be some confusion on PPRuNe regarding GA arming.

Someone stated a Radio Altitude input.
I just have glideslope capture and flaps out of up. After a little fishing, it seems to be trailing edge flaps. i.e. flap lever >1 unit.

An "or" gate is also shown in the A/T computer logic.

emerydc8

I've never heard about the RA. Nothing in any manual I have.

John H Watson

#86
QuoteAfter a little fishing, it seems to be trailing edge flaps. i.e. flap lever >1 unit.

Strange. Only one manual has this ">1 unit". The others seem to go on flaps in general.

This YouTube video seems to show G/A at flaps 1, prior to G/S capture:

https://www.youtube.com/watch?v=O3ZKv6-0MQc

The RA kept popping in and out (so the video starts around 2500')'

Jeroen Hoppenbrouwers


Martin Baker

https://youtu.be/GR4xhTF-13g

I find this guy's style and content fascinating - this is his commentary on the preliminary report.

John H Watson

There is too much misinformation in this guy's comments. He corrected himself with the alternate EFIS selection, but he talks about the speedbrakes auto-retracting during go-around.

The F/O's instrumentation failure doesn't seem to be stressed enough. Did he actually see the instruments telling him he was stalling and responded accordingly?


Jeroen Hoppenbrouwers

Final report is out.

https://avherald.com/h?article=4c497c3c/0002

QuoteThe NTSB determines that the probable cause of this accident was the inappropriate response by the first officer as the pilot flying to an inadvertent activation of the go-around mode, which led to his spatial disorientation and nose-down control inputs that placed the airplane in a steep descent from which the crew did not recover. Contributing to the accident was the captain's failure to adequately monitor the airplane's flightpath and assume positive control of the airplane to effectively intervene. Also contributing were systemic deficiencies in the aviation industry's selection and performance measurement practices, which failed to address the first officer's aptitude-related deficiencies and maladaptive stress response. Also contributing to the accident was the Federal Aviation Administration's failure to implement the pilot records database in a sufficiently robust and timely manner.

United744

The F/O was a total liability and shouldn't have even been sat in that seat at the time of the accident. A sad day for all concerned. :(