Atlas Air 767 down/Texas
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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.
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.
[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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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.
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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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.
SkyGod
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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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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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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.
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.
- 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.
I don’t believe they had flaps or slats extended in which case TOGA is not even armed
i don’t 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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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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I don’t 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,
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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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.
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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"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.
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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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 hasn’t thinly sourced his articles.
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But we‘ll see.
