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Atlas Air 767 down/Texas

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Atlas Air 767 down/Texas

Old 16th Mar 2019, 09:26
  #601 (permalink)  
 
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Educated Airman says: "The question with Atlas is what caused the un-commanded nose drop."

. . . Could you conceptualize that it may not have been uncommanded?
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Old 16th Mar 2019, 09:46
  #602 (permalink)  
 
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Originally Posted by stilton View Post



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
I must admit that was my initial thought. As it fits with the claimed background voice in the last response to ATC. Pull up to avoid a head on with a large drone then damage from the impact and LOC
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Old 16th Mar 2019, 09:53
  #603 (permalink)  
 
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Originally Posted by AviatorDave View Post
It‘s hard to believe that a 11.000 hour captain cannot recover from a power-surge related pitch up at 6000ft in daylight if that‘s the only condition the crew would have had to deal with.
That is if they immediately identified the thrust surge and the reason for it. If not, in IMC it would drastically amplify the Nose Up feeling. The somatogravic illusion of a combination of a sudden and massive thrust increase (from almost flight idle to TOGA?) combined with the resulting real pitch up moment will be massive. Combined with a startle effect while their minds were focussed on going around weather this could have led to temporary confusion. In the Rostov Crash the Crew even deliberately set TOGA and still drove it manually into the ground, despite a planned thrust change. In IMC surprise plus illusion is a serious adversary...
And 10 - 15s (when they came out of the clouds they apparently started the recovery but obviously too late) is not that long, if we look at LoC accidents of the last 10 Years where Crews were confused for up to minutes when outside reference was missing.
So, unfortunately, I would not completely rule out such a scenario.
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Old 16th Mar 2019, 09:59
  #604 (permalink)  
 
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Originally Posted by Ian W View Post
I must admit that was my initial thought. As it fits with the claimed background voice in the last response to ATC. Pull up to avoid a head on with a large drone then damage from the impact and LOC
Guys, you can be sure that by now NTSB will know if the ND attitude was due to Control input or caused by aerodynamic disturbance due to damage (from a drone/bird/whatever).
It is honorable but seriously clutching at straws by now. I just hope (and also firmly believe) that it was purely accidental and not deliberate.
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Old 16th Mar 2019, 11:03
  #605 (permalink)  
 
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Looks like somebody just got over-excited with the elevator in the turbulence
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Old 16th Mar 2019, 13:02
  #606 (permalink)  
 
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Only other thing I can think of, is that they ran under the bottom of a cell that Approach wasn't painting for some reason. Could have been a microburst?.... something similar to Delta at DFW in 1985. They can form fast. I was headed from DAL to MRY in a Falcon Jet that afternoon and was vectored right over the top of DFW westbound at 4,000. It was a nice sunny VFR afternoon with scattered puffy white clouds just above me and it was an unusual sight to be directly overhead DFW. When I got to MRY the line guys were all talking about Delta crashing in a thunderstorm at DFW. I couldn't believe that they had the right airport, since I'd passed overhead about 45 minutes prior to the crash. Of course, that was in August, and Delta was on the ILS.... a lot lower than Atlas.
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Old 16th Mar 2019, 14:42
  #607 (permalink)  
 
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High Thrust
-> Nose Down Trim from Autopilot or MCAS
-> High Speed
-> Insufficient Elevator Authority to pull out of dive + pulling back thrust takes away positive pitch moment when most needed + air load can stall trim.

Seems to be a common factor with Rostov, Houston, Lion, Ethiopian?


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Old 16th Mar 2019, 15:00
  #608 (permalink)  
 
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Originally Posted by Mr Angry from Purley View Post
Flight was daylight, should we not wait until we see the schedule before making "assumed" statements of fatigue
If you are familiar with ACMI cargo operations, one can assume fatigue most likely played a factor. It's a fact of life in the industry.
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Old 16th Mar 2019, 15:50
  #609 (permalink)  
 
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Very hard to believe pilots of this freighter sat and watched their jet plunge nearly straight down while not taking corrective action. When descending 2.5 degrees is very noticeable, 5 deg. is a very steep descent, 10 degrees starts filling the ADI with all brown, you only see this in the SIM world. Any airliner heading down at 49 degrees is out of control and will not likely recover without 20K feet and very careful inputs.
When I heard the ATC "pull" I immediately thought someone seen something out front.
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Old 16th Mar 2019, 16:42
  #610 (permalink)  
 
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Let’s not go overboard with the “turbulence”.
This is a big aircraft, it will take a lot for it to be ‘extreme’ for a turbulence induced loss of control.

Last edited by B2N2; 16th Mar 2019 at 16:56.
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Old 16th Mar 2019, 18:46
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Originally Posted by B2N2 View Post
Let’s not go overboard with the “turbulence”.
This is a big aircraft, it will take a lot for it to be ‘extreme’ for a turbulence induced loss of control.
Indeed. Having experienced severe turb in this ac ( eg. 700 ft drop in seconds and 51 degr bank angle, of course near Gander, jetstream turned 180 there), having to use max thrust to stay on the ILS G/S into MIA in a downdraft(microburst?) etc. gave me a lot of confidence in this ac. I am sure fellow airmen have seen worse...
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Old 16th Mar 2019, 19:29
  #612 (permalink)  
 
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Originally Posted by stilton View Post
In the picture I saw the left side of the horizontal stabilizer looked damaged, perhaps they hit a drone
A picture of it after it followed the rest of the aircraft into the ground at high speed? What piece of wreckage have we seen a picture of that wasn't damaged?
Maybe I misunderstand your statement.
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Old 16th Mar 2019, 19:49
  #613 (permalink)  
 
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When max thrust is applied at low level in an airliner at landing weight, the human vestibular balance system will perceive that longitudinal acceleration as a pitch-up, especially in the absence of strong visual cues (ie, good VMC flight conditions).

The instinctive pilot reaction to longitudinal acceleration is to push the control column forward to maintain what he perceives as a necessary control correction to maintain a constant aircraft pitch attitude. This reaction is especially strong if the pilot has been flying with visual references and then subtly loses such visual reference and enters instrument flight conditions but still believes that he is in visual flight.

The secondary effect of thrust application is also an upwards pitching moment on the aircraft and this reinforces the need for the pilot to instinctively push the control column forward (and trim) with any thrust increase.

This principal of fooling the human vestibular balance system is employed in 6 axis Flight Simulators to imitate the motions of aircraft flight.

Perception of an increasing pitch up by the pilot flying in response to the increase in thrust may have triggered him to push the control column forward until such time as he recognized the actual very steep pitch attitude on re-attaining strong visual cues on exiting the cloud base in the subsequent dive.

This principle might be a factor in the subject accident.
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Old 16th Mar 2019, 20:02
  #614 (permalink)  
 
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@Flexibile:
Do you think it fair to presume that the pilot in this aircraft didn't have an instrument scan going? (Called by some a 'crosscheck')
If you are on instruments, then you fly with the AI/AHRS/HSI as your primary reference. You get trained to do that when you get an instrument rating.
(Granted, any of us can have a scan breakdown on a bad day).
So while what you say has been shown to be true, the remedy for that issue is also known:
establish a scan and use it to maintain attitude, performance, etc.
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Old 16th Mar 2019, 20:16
  #615 (permalink)  
 
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What appears to have been a perfectly serviceable B767 flown by a competent and experienced crew crashed after entering a steep dive.

The reason for the accident is unknown at this stage.

I presume nothing.
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Old 16th Mar 2019, 20:21
  #616 (permalink)  
 
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Originally Posted by FlexibleResponse View Post
When max thrust is applied at low level in an airliner at landing weight, the human vestibular balance system will perceive that longitudinal acceleration as a pitch-up, especially in the absence of strong visual cues (ie, good VMC flight conditions).

The instinctive pilot reaction to longitudinal acceleration is to push the control column forward to maintain what he perceives as a necessary control correction to maintain a constant aircraft pitch attitude. This reaction is especially strong if the pilot has been flying with visual references and then subtly loses such visual reference and enters instrument flight conditions but still believes that he is in visual flight.

The secondary effect of thrust application is also an upwards pitching moment on the aircraft and this reinforces the need for the pilot to instinctively push the control column forward (and trim) with any thrust increase.

This principal of fooling the human vestibular balance system is employed in 6 axis Flight Simulators to imitate the motions of aircraft flight.

Perception of an increasing pitch up by the pilot flying in response to the increase in thrust may have triggered him to push the control column forward until such time as he recognized the actual very steep pitch attitude on re-attaining strong visual cues on exiting the cloud base in the subsequent dive.

This principle might be a factor in the subject accident.
This very thing! You are not alone in this theory...

Having flown the 767 for sometime now and as others have alluded to, MAX thrust at that weight/altitude is no joke when it comes to acceleration. So +1 on that this could be a factor. Its plausible and it could be something that simple. The only thing I cant resolve is why/how did MAX thrust get commanded.


Cheers
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Old 16th Mar 2019, 20:23
  #617 (permalink)  
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I think most professional pilots have internalized the scan...it takes place without thought...case in point, years ago we were ferrying a lear with the attitude indicators inop..using just the peanut gyro..we found you had to tape over the bad instruments, because you see and respond to the bad gyros even when your conscious mind knows not to
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Old 16th Mar 2019, 21:38
  #618 (permalink)  
 
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Originally Posted by Lonewolf_50 View Post
@Flexibile:
Do you think it fair to presume that the pilot in this aircraft didn't have an instrument scan going? (Called by some a 'crosscheck')
If you are on instruments, then you fly with the AI/AHRS/HSI as your primary reference. You get trained to do that when you get an instrument rating.
(Granted, any of us can have a scan breakdown on a bad day).
So while what you say has been shown to be true, the remedy for that issue is also known:
establish a scan and use it to maintain attitude, performance, etc.

What if they had a instrument problem that caused the aircraft to present bad attitude information (nose high). Next the crew adds max thrust and pushes forward on the control column to lower AOA /the perceived unusual attitude towards “level.” Then they are trying to determine whether the attitude information is wrong or if they had a pitot static issue. Once the break out of the clouds they recognise the severity of the situation and start to pull up, but given the high load factor from doing nearly 400KIAS they can only recover to -20 degrees pitch.
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Old 16th Mar 2019, 22:27
  #619 (permalink)  
 
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Originally Posted by V1rhot8 View Post



What if they had a instrument problem that caused the aircraft to present bad attitude information (nose high). Next the crew adds max thrust and pushes forward on the control column to lower AOA /the perceived unusual attitude towards “level.” Then they are trying to determine whether the attitude information is wrong or if they had a pitot static issue. Once the break out of the clouds they recognise the severity of the situation and start to pull up, but given the high load factor from doing nearly 400KIAS they can only recover to -20 degrees pitch.

Pretty good theory... Especially for the "why max thrust" question.
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Old 16th Mar 2019, 23:00
  #620 (permalink)  
 
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Originally Posted by FlexibleResponse View Post
What appears to have been a perfectly serviceable B767 flown by a competent and experienced crew crashed after entering a steep dive. The reason for the accident is unknown at this stage. I presume nothing.
Fair reply. *tips cap*

For V1rhot8
Interesting scenario, not beyond the possible depending on flight conditions at initiation of the event.
We'll see.
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