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Atlas Air 767 down/Texas

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Atlas Air 767 down/Texas

Old 16th Mar 2019, 02:46
  #581 (permalink)  
 
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Originally Posted by Airbubba View Post
Which begs the question, were the throttles still at max all the way down and if so why?

And was the autopilot really on until impact?
Don't know for sure, but the quote about fighting the automation was from Greig Feith, former NTSB guy (https://aeronauticsonline.com/ntsb-r...air-767-crash/) He must still have contacts on the board, I would think. Supposedly, according to the article, they managed to reduce the pitch to only 20 degrees nose low, but it sure doesn't look like that on the video clip that was posted online showing it just prior to impact. The story originally said that the speed was close to 500 kts at impact, but that part seems to have been edited out of the story now. Sure hope it wasn't intentional.
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Old 16th Mar 2019, 02:50
  #582 (permalink)  
 
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This is very hard to believe, Airbubba. Not taking you to task, but very skeptical of Andy the twitter entity.
49 degrees nose down is a non trivial departure from anything remotely resembling normal corrective action in a transport aircraft. It's the kind of pitch angle down that you'd see in an aerobatic display.
While I will await further amplifying information, massive nose down pitch of that magnitude is an over-control that is way out of limits for the flight regime the crew were in: getting themselves set up for a standard approach into an airport.
If my hand bumps the control, engine or otherwise, it takes a certain amount of time of "nobody is near the yoke" for that to go from normal flying to 49 degrees nose down and for that to not be immediately corrected.
We'll see what further NTSB releases reveal.
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Old 16th Mar 2019, 02:51
  #583 (permalink)  
 
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Having experienced a severe windshear that was some what anticipated in cavu on approach to Sedona Arizona, I can tell you that it is instinctive to push the yoke and throttles when the nose drops un- commanded. For my experience, that was the right thing to do even if I was only 500 AGL. The question with Atlas is what caused the un-commanded nose drop.
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Old 16th Mar 2019, 02:54
  #584 (permalink)  
fdr
 
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Originally Posted by Educated Airman View Post
I am still thinking about the missing bolt on the horizontal stab actuator theory. If this happened the stab would most likely have moved beyond the design limits and could possibly have caused contact with the elevator control cables resulting in an overload of one of the many pulley quadrants. This would cause the cables to go slack and the elevators to assume and retain any arbitrary position. If there is a control column position channel on the FDR and it does not agree with the elevator position, a probable cause could be stab movement beyond design limits. Once the horizontal stab stalled out due to pitch momentum, the excessive nose down AOA could have a wing area effect on the stab (Due to center of lift and hinge location) to blow it into a nose up position resulting in the final pull up.
The 767 is a conventional geometry aircraft: The stab provides a negative lift force to balance the nose down pitching moment of the wing. If the actuator becomes fully free of constraint, the aerodynamic load on the stab will drive it to stabilizer leading edge down, which increases the negative lift, and results in a pitch up. The normal force from the section is forward of the remaining hinge line, and will result in the stabiliser increasing LE down (pitch up).This was not the case for an aircraft that pitched nose down in wings level flight. (Sorry...)

[if you get up close and personal with the stab, you will see that it is a cambered section, with the camber towards the bottom, not the top]
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Old 16th Mar 2019, 02:56
  #585 (permalink)  
 
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What about inadvertent selection of TOGA mode? - hand resting on the thrust levers then turbulence causes one of the two TOGA switches to be pushed.

Would make more sense than the thrust levers being manually pushed forward.

Last edited by Eric Janson; 16th Mar 2019 at 04:51.
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Old 16th Mar 2019, 03:00
  #586 (permalink)  
 
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Originally Posted by log0008 View Post
Turbulence causing a pilots hand to push the engines to t/o power and then a massive pitch down control input sounds like the most strange and extraordinary cause of a crash I've read, has to more to it surely?
I agree. Like everybody else, I've been in some pretty heavy turbulence and I don't remember that it ever caused me to jam the throttles to the stops. And the acft supposedly was on the A/P, so it would had to have disconnected in order to get a pitch up from the increased thrust, in any case. Even if all that had happened, I don't see them pushing massively on the yokes to correct was only a few hundred foot climb. Sounds more like a Keystone Cops movie.
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Old 16th Mar 2019, 03:03
  #587 (permalink)  

SkyGod
 
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Originally Posted by Eric Janson View Post
What about inadvertent selection of TOGA mode? - hand resting on the thrust levers than turbulence causes one of the two TOGA switches to be pushed.

Would make more sense than the thrust levers being manually pushed forward.
No,
The 767 is an easy, docile Jet, no risk of inadvertent selection of TOGA mode, none whatsoever unless you are totally incompetent and I doubt these guys were. (Unless one of them was suicidal, then anything and everything is on the table)
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Old 16th Mar 2019, 03:09
  #588 (permalink)  
 
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Originally Posted by Eric Janson View Post
What about inadvertent selection of TOGA mode? - hand resting on the thrust levers than turbulence causes one of the two TOGA switches to be pushed.

Would make more sense than the thrust levers being manually pushed forward.
I don't buy this hypothesis reported by the Wall Street Journal writer. I really doubt that they were hand flying while driving around in some chop. And if TOGA was selected accidentally for some reason, they would have simply pulled the throttles back. It wouldn't have caused them to have go ape....
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Old 16th Mar 2019, 03:11
  #589 (permalink)  
 
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The hinge line is aft of the center of lift, but forward of the planform area center. Once the stab stalls out, the air force on the top of the surface will push the stab back to a stab nose down position.
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Old 16th Mar 2019, 03:14
  #590 (permalink)  
 
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Devil

Originally Posted by Vessbot View Post
There are 2 completely different double entendres at play here, I'm not sure which one you meant but my hat's off if it is both!
Hilarious
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Old 16th Mar 2019, 03:19
  #591 (permalink)  
 
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Reminds me of a scenario I saw in a 767 Sim a few years ago. A standard Go-Around from about 200ft AGL with autopilot engaged. Missed approach altitude was 3000ft. Everything appeared normal, we had altitude capture and the nose lowered as we approached 3000ft. BUT the nose kept dropping and dropping. At about 20 degrees nose down I disconnected the autopilot and manually flew a nose low upset recovery. It turns out the automatics had not captured 3000ft but a much lower altitude (we suspected about 1000ft). So the mechanics of what happen was as follows:
- After pressing the Go-Around switches the engines went to Go-Around thrust (normal).
- The Autopilot raises the nose to climb away (normal).
- The Autopilot trims the STAB nose down to counteract the large nose-up pitching moment due to Go-Around thrust (normal).
- The automatics captured ~1000ft instead of 3000ft (NOT normal).
- As we were climbing (or had climbed) through 1000ft, the autopilot commanded a nose down attitude to regain 1000ft.
- With the nose attitude decreasing and Go-Around thrust set, the speed started increasing rapidly.
- The autothrottle then set idle thrust in attempt to control the speed.
- Now here's the kicker: The autopilot had trimmed nose down to counteract Go-Around thrust. With the thrust rapidly reduced to idle, the now unbalanced pitching moments caused the pitch attitude to rapidly drop through 20 degrees nose down. The autopilot did not react quick enough to counteract the rapid nose down pitch change.

That might be a factor in this incident. Go-Around thrust activated. Nose down trim applied to counteract the nose-up pitching moment caused by Go-Around thrust. Nose lowered to regain the vertical path, but speed rapidly increases due Go-Around thrust. Thrust rapidly reduced to control speed. Pitching moments are now unbalanced and nose rapidly drops to a very nose low attitude. Startle effect and confusion overwhelms the crew.
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Old 16th Mar 2019, 03:32
  #592 (permalink)  
 
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18 seconds from the initial loss of control to impact. Even considering the startle factor and an assumedly fatigued crew, something doesn't add up.
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Old 16th Mar 2019, 05:29
  #593 (permalink)  
 
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Originally Posted by Eric Janson View Post
What about inadvertent selection of TOGA mode? - hand resting on the thrust levers then turbulence causes one of the two TOGA switches to be pushed.

Would make more sense than the thrust levers being manually pushed forward.

I donít believe they had flaps or slats extended in which case TOGA is not even armed


i donít buy the WSJ theory for a moment, makes absolutely no sense



In the picture I saw the left side of the horizontal stabilizer looked damaged, perhaps they hit a drone
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Old 16th Mar 2019, 05:53
  #594 (permalink)  
 
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I find it very hard to believe that someone's arm could have been "jostled" to that extent - but what if one of the pilots (or the jump seat passenger) was out of their seat, and sudden turbulence knocked them off their feet and into the controls? It seems that an individual stumbling into the controls would be more likely to knock levers or other controls out of position, and if the individual landed in the PF's lap, maybe by the time that was sorted, the situation might have been unrecoverable?
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Old 16th Mar 2019, 06:11
  #595 (permalink)  
 
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I guess they should put some pilots in a sim and try out a bunch of scenarios.
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Old 16th Mar 2019, 08:11
  #596 (permalink)  
 
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Originally Posted by Airbubba View Post
Here's the article from Andy Pasztor:






I donít buy this story which sounds like a very bad student pilot screwup. These guys were no rookies. Both CA and FO had total time well in the thousands, and while the FO appeared to be relatively new on type with 520 hours, the CA had around 1250 hours.
A technically well functioning 767 is not known as a problematic or difficult to handle aircraft.
I have been training rookie student pilots to deal with unexpected power surges and losses in light pistons, but none of them would have augured in while trying to recover from a sudden pitch-up due to unexpectedly firewalling the throttle,
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Old 16th Mar 2019, 08:16
  #597 (permalink)  
 
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Originally Posted by Murexway View Post
I agree. Like everybody else, I've been in some pretty heavy turbulence and I don't remember that it ever caused me to jam the throttles to the stops. And the acft supposedly was on the A/P, so it would had to have disconnected in order to get a pitch up from the increased thrust, in any case. Even if all that had happened, I don't see them pushing massively on the yokes to correct was only a few hundred foot climb. Sounds more like a Keystone Cops movie.
So much doesn't make sence, I'm still a flight instructor so can't comment on jets but i just can't see it happening. Sure there have been plenty of times where turbulence, has lead to a small un intended power movements but these are always felt and able to be reacted to quickly and without any effect on the flight, and thats in a piston aircraft, i'm sure a jet responds even more slowly. Also again not being an airline pilot but would a pilots hand even be anywhere near the throttles with the aircraft on autopilot at 7000ft or so?

I don't have the data but to me I just can't see how this situation could be possible, I'm thinking maybe someone has been misquoted and the auto throttles somehow activated t/o power. That or someone has the order stuffed, a nose pitch down to 49 degrees now rapid enough that could cause an unintentional fwd movement of the throttles.

Last edited by log0008; 16th Mar 2019 at 08:37.
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Old 16th Mar 2019, 08:23
  #598 (permalink)  
 
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Originally Posted by runner1021 View Post
18 seconds from the initial loss of control to impact. Even considering the startle factor and an assumedly fatigued crew, something doesn't add up.
Flight was daylight, should we not wait until we see the schedule before making "assumed" statements of fatigue
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Old 16th Mar 2019, 08:44
  #599 (permalink)  
 
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"according to people familiar with the details"

These sort of unattributed leaks should be taken with a bag of salt. Happens all too often that journalists looking for a good story are willing to listen to anyone with gossip to share.

However, there have been several cases of somewhat inexplicable, and inexcusable handling errors over the past few years.
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Old 16th Mar 2019, 08:56
  #600 (permalink)  
 
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I would be surprised if Pasztor is far off the mark. He is one of the if not the most senior aviation writer at the Wall Street Journal. Historically he hasnít thinly sourced his articles.
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