F9Animal wrote:

No question they were trying to get the nose up before impact. This really raises my suspicion that spatial disorientation may be possible here. Is it safe to say they were in the clouds when they began their plunge?

Just gut wrenching video.

I'm curious how you come to that conclusion. I've watched the video a number of times and nothing indicates there was any change in direction. Forget trying to focus on the plane. Focus on the bubble in the video. It remains centered on the plane. Just watch the movement of that light bubble down the screen. It never changes the angle in which it is moving. The clip is too short and too obstructed by trees to draw any kind of conclusion that the pilots were attempting to do anything. The camera sits at an angle and the plane is coming in at an angle and flying off to the distance. Any appearance of a change in flight is likely an optical illusion. Again.. just watch the bubble angle. This doesn't imply that anything nefarious happened. They may have had zero control over the plane for who knows what reason. We don't know until more details are released.

Is that largest piece that he talked about in the corner of the warehouse one of the winglets?

Indy wrote:

F9Animal wrote:

No question they were trying to get the nose up before impact. This really raises my suspicion that spatial disorientation may be possible here. Is it safe to say they were in the clouds when they began their plunge?

Just gut wrenching video.

I'm curious how you come to that conclusion. I've watched the video a number of times and nothing indicates there was any change in direction. Forget trying to focus on the plane. Focus on the bubble in the video. It remains centered on the plane. Just watch the movement of that light bubble down the screen. It never changes the angle in which it is moving. The clip is too short and too obstructed by trees to draw any kind of conclusion that the pilots were attempting to do anything. The camera sits at an angle and the plane is coming in at an angle and flying off to the distance. Any appearance of a change in flight is likely an optical illusion. Again.. just watch the bubble angle. This doesn't imply that anything nefarious happened. They may have had zero control over the plane for who knows what reason. We don't know until more details are released.

First of all you’re watching the wrong video. The one with the bubble is the one that’s been modified by the press. Watch the raw video that shows everything as it is. Much easier to view without that moving bubble.

pugman211 wrote:

GEUltraFan9XGTF wrote:

Video of the wreckage found so far:
https://youtu.be/-G-KfcFQg9U

At 4:28 in the video, you can see the jackscrew for the tailplane (I could be wrong though). It's at it's lowest/highest point on the screw? Does that look about right?

Excellent point on the (potential) tailplane jackscrew. Being only a GA pilot, I can only speculate, but I think you're right. And the nut does seem to be at near (or full) stop, being close to the jackscrew motor. A quick Google search failed to yield a diagram of the 767's tailplane jackscrew assembly, so I must be using the wrong keywords.

SO...QUESTION: for those of you in the know, is that jackscrew nut position indicative of a nose-up or nose-down trim?

alggag wrote:

Lrockeagle wrote:

HoboJoe wrote:

Not gonna glide too far from 6000 ft

Bout twice as far as Sully did. Idk the glide ratio on a 76 but it’s probably at least 8-1. That would be 9 miles of glide. (Statute miles, I know some of you will argue my math)

Edit: Google says 12:1 per Gimli. So 13.6 miles of glide. May not get you to the airport but it’ll help find somewhere flat to set down, and Houston has a whole lot of flat

Flat land, swamps, even some GA airports would have been in range for a theoretical dead stick landing.

Ellington field is the first thing that comes to mind.

pugman211 wrote:

GEUltraFan9XGTF wrote:

Video of the wreckage found so far:
https://youtu.be/-G-KfcFQg9U

At 4:28 in the video, you can see the jackscrew for the tailplane (I could be wrong though). It's at it's lowest/highest point on the screw? Does that look about right?

If the NTSB suspected mechanical failure, would they really let journalists in the facility where they are storing the recovered parts?

Edited because of incorrect time stamp quoted

Interesting observation. I wonder if anyone here can confirm it is the tail plane jack skrew? Or could it be a drive for the rudder, or for the flaps?
In any case, it seems to be at about 70 to 80 percent of travel from the mid point, but in which direction, if it is from the tail plane?

Edit: Maybe it belongs to the gear retraction system?

In the Turkish 981 DC-10 crash in 1974, the crew had lost all control of the aircraft and it entered a 20-degree nosedive. As it neared the ground, its trajectory began to flatten out as a result of the tremendous speed the aircraft gained on the way down.

IAHWorldflyer wrote:

NTSB says they plan to release a transcript of the CVR in the next week. Will be interesting to see that.

I have a question for those who work in aviation here. The NTSB says the audio quality of the CVR is poor and needs some enhancement. On this thread people have said by looking at the pictures that this is likely an original Siemens product which would date it over 20 years old. Do these old ones work like the cassette tapes of my youth in that they just erase and tape over old conversations? If that's the case, wouldn't the sound quality be expected to deteriorate over decades? Or do they not use magnetic tape to record?

The photos seem to show solid state recorders.

LTC8K6 wrote:

IAHWorldflyer wrote:

NTSB says they plan to release a transcript of the CVR in the next week. Will be interesting to see that.

I have a question for those who work in aviation here. The NTSB says the audio quality of the CVR is poor and needs some enhancement. On this thread people have said by looking at the pictures that this is likely an original Siemens product which would date it over 20 years old. Do these old ones work like the cassette tapes of my youth in that they just erase and tape over old conversations? If that's the case, wouldn't the sound quality be expected to deteriorate over decades? Or do they not use magnetic tape to record?

The photos seem to show solid state recorders.

Correct, LTC.

It's not per se a Siemen's product. It's a Fairchild/Allied Signal/Honeywell (specifically Allied Signal) CVR, original to the plane. SIemens did buy Honeywell, but it's a bit of a stretch to call this a Siemens product per se.

They had solid state recorders 20 years ago. This is one of them. It's a good one. The issue is the microphones.

And they're not going to release a transcript next week. An official transcript is going to take months. They might release a summary.

SteinarN wrote:

pugman211 wrote:

GEUltraFan9XGTF wrote:

Video of the wreckage found so far:
https://youtu.be/-G-KfcFQg9U

At 4:28 in the video, you can see the jackscrew for the tailplane (I could be wrong though). It's at it's lowest/highest point on the screw? Does that look about right?

If the NTSB suspected mechanical failure, would they really let journalists in the facility where they are storing the recovered parts?

Edited because of incorrect time stamp quoted

Interesting observation. I wonder if anyone here can confirm it is the tail plane jack skrew? Or could it be a drive for the rudder, or for the flaps?
In any case, it seems to be at about 70 to 80 percent of travel from the mid point, but in which direction, if it is from the tail plane?

Edit: Maybe it belongs to the gear retraction system?

I couldn’t find a picture of a 67 THS actuator, but this appears to be a 738 THSA, which looks very similar to what we can see in the video.



Edit: also here’s a video showing the 777 THSA. about half way through the video.

https://youtu.be/Sy-ARLZXXTA

Good observations. So based on the 738 pic above and what we see in the video at 4:28, the jack screw on the wrecked 763 would have been at a much greater “nose up” type attitude right? Obviously that doesn’t show what the elevators were doing. Does that jackscrew control trim?

I cannot tell if the angle changes or it's just an illusion, but if you press me, I'd say the angle does not change.

The NTSB will be able to give us the angle at impact.

Western727 wrote:

pugman211 wrote:

GEUltraFan9XGTF wrote:

Video of the wreckage found so far:
https://youtu.be/-G-KfcFQg9U

At 4:28 in the video, you can see the jackscrew for the tailplane (I could be wrong though). It's at it's lowest/highest point on the screw? Does that look about right?

Excellent point on the (potential) tailplane jackscrew. Being only a GA pilot, I can only speculate, but I think you're right. And the nut does seem to be at near (or full) stop, being close to the jackscrew motor. A quick Google search failed to yield a diagram of the 767's tailplane jackscrew assembly, so I must be using the wrong keywords.

SO...QUESTION: for those of you in the know, is that jackscrew nut position indicative of a nose-up or nose-down trim?

Looks like almost full nose up to me....

trnswrld wrote:

Good observations. So based on the 738 pic above and what we see in the video at 4:28, the jack screw on the wrecked a 763 would have been at a much greater “nose up” type attitude right? Obviously that doesn’t show what the elevators were doing. Does that jackscrew control trim?

Yes the jackscrew is for trim. I believe it’s in an almost full nose up trim config.

Here is mention of another flight having pitch issues descending through 6,000'. Happened in 2001 and the crew were able to recover, but the NTSB apparently were unable to find a specific cause.

From: https://www.flightglobal.com/news/artic ... ve-456078/

"...the NTSB probed a March 2001 pitch control incident which occurred to an American Airlines 767-300 as it descended through 6,000ft on approach to Paris.

"Its crew found the jet did not respond as expected to control column input, and the pilots resorted to using horizontal stabiliser trim to control pitch.

"US investigators could not find any discrepancies in the stabiliser components – including bellcranks, power control units and shear rivets – and tests suggested the jet might have been affected by water entering the empennage and freezing on the elevator control system. A similar incident had occurred on another 767 during approach to Zurich a month after the American event."

HoboJoe wrote:

spacecadet wrote:

SeaKing4 wrote:

Even if it was half that 6187.5 litres is still a lot of fuel. So where is it.

Probably stuck in the mud.

If you're suggesting fuel starvation, running out of fuel does not cause airliners to drop out of the sky like a stone. Pilots are in fact trained on how to glide their aircraft, and every aircraft is designed to glide. The 767 has had fuel starvation incidents in the past, some of which are quite famous, and it's more than capable of gliding down safely.

Even if this plane ran out of fuel, that would not cause it to crash like this.

Not gonna glide too far from 6000 ft

For descent planning at idle thrust, we generally planned at 280 KIAS, 3 miles for every 1,000 feet. So at 6,000' above sea level (IAH's elevation is almost 100'), the glide would have been about 18 miles, even more at slower - more optimal - speeds. Certainly not enough to reach IAH, but a dual engine failure wouldn't result in a dive as documented in the videos.

If you're wondering what an airliner looks like in a power-less glide, check out the Sully/US1549 videos.

astaz wrote:

Western727 wrote:

pugman211 wrote:

At 4:28 in the video, you can see the jackscrew for the tailplane (I could be wrong though). It's at it's lowest/highest point on the screw? Does that look about right?

Excellent point on the (potential) tailplane jackscrew. Being only a GA pilot, I can only speculate, but I think you're right. And the nut does seem to be at near (or full) stop, being close to the jackscrew motor. A quick Google search failed to yield a diagram of the 767's tailplane jackscrew assembly, so I must be using the wrong keywords.

SO...QUESTION: for those of you in the know, is that jackscrew nut position indicative of a nose-up or nose-down trim?

Looks like almost full nose up to me....

Yes, if it is the same design as pictured on the 737. But, can this be possible? If the jack screw is almost full nose up, how come the airplane plunged like it did? Even if we suppose the trim was running towards nose up at the time of impact, how many seconds would it need to run to this apparent position from lets say a neutral position? Would it be possible at all in the available 18 to 20 sec to first get the airplane to start plunging where the jack screw obviously cant have been in almost full nose up position, and then at some time before impact start running in the nose up direction and have time to reach the position it seems to have at impact? And another question, considering the very high indicated airspeed the aircraft had at impact, would an almost full nose up trim position be compatible with wings AoA below a value where generated lift wouldnt tear the wings off the aircraft?

What would the AoA be for the airspeed the aircraft is assumed to have had at impact and generating say 3G? I believe somewhere between say 5 to 9 degrees AoA at say 400 knots at low altitude would produce so much lift that the wings would tear off. So, could it be possible that the tail plane was not in the postion that the screw jack is indicating, ie that the screw jack had broken loose in one end before impact?

fabian9 wrote:

trnswrld wrote:

Good observations. So based on the 738 pic above and what we see in the video at 4:28, the jack screw on the wrecked a 763 would have been at a much greater “nose up” type attitude right? Obviously that doesn’t show what the elevators were doing. Does that jackscrew control trim?

Yes the jackscrew is for trim. I believe it’s in an almost full nose up trim config.

If true, that's very, very sobering.

SteinarN wrote:

astaz wrote:

Western727 wrote:

Excellent point on the (potential) tailplane jackscrew. Being only a GA pilot, I can only speculate, but I think you're right. And the nut does seem to be at near (or full) stop, being close to the jackscrew motor. A quick Google search failed to yield a diagram of the 767's tailplane jackscrew assembly, so I must be using the wrong keywords.

SO...QUESTION: for those of you in the know, is that jackscrew nut position indicative of a nose-up or nose-down trim?

Looks like almost full nose up to me....

Yes, if it is the same design as pictured on the 737. But, can this be possible? If the jack screw is almost full nose up, how come the airplane plunged like it did? Even if we suppose the trim was running towards nose up at the time of impact, how many seconds would it need to run to this apparent position from lets say a neutral position? Would it be possible at all in the available 18 to 20 sec to first get the airplane to start plunging where the jack screw obviously cant have been in almost full nose up position, and then at some time before impact start running in the nose up direction and have time to reach the position it seems to have at impact? And another question, considering the very high indicated airspeed the aircraft had at impact, would an almost full nose up trim position be compatible with wings AoA below a value where generated lift wouldnt tear the wings off the aircraft?

What would the AoA be for the airspeed the aircraft is assumed to have had at impact and generating say 3G? I believe somewhere between say 5 to 9 degrees AoA at say 400 knots at low altitude would produse so much lift that the wings would tear off. So, could it be possible that the tail plane was not in the postion that the screw jack is indicating, ie that the screw jack had broken loose in one end before impact?

I'm sorry, I didn't see this reply previously. Great points on the time required for the motor to move from neutral to that much nose-up trim. I wonder as well.

As well, I recall AS261's jackscrew having thread shavings around it. That doesn't appear to be the case here, based on the brief look at that video of the crashed 763's elevator trim jackscrew. Obviously, the DFDR will be key, so I look forward to what the NTSB eventually releases.

SteinarN wrote:

astaz wrote:

Western727 wrote:

Excellent point on the (potential) tailplane jackscrew. Being only a GA pilot, I can only speculate, but I think you're right. And the nut does seem to be at near (or full) stop, being close to the jackscrew motor. A quick Google search failed to yield a diagram of the 767's tailplane jackscrew assembly, so I must be using the wrong keywords.

SO...QUESTION: for those of you in the know, is that jackscrew nut position indicative of a nose-up or nose-down trim?

Looks like almost full nose up to me....

Yes, if it is the same design as pictured on the 737. But, can this be possible? If the jack screw is almost full nose up, how come the airplane plunged like it did? Even if we suppose the trim was running towards nose up at the time of impact, how many seconds would it need to run to this apparent position from lets say a neutral position? Would it be possible at all in the available 18 to 20 sec to first get the airplane to start plunging where the jack screw obviously cant have been in almost full nose up position, and then at some time before impact start running in the nose up direction and have time to reach the position it seems to have at impact? And another question, considering the very high indicated airspeed the aircraft had at impact, would an almost full nose up trim position be compatible with wings AoA below a value where generated lift wouldnt tear the wings off the aircraft?

What would the AoA be for the airspeed the aircraft is assumed to have had at impact and generating say 3G? I believe somewhere between say 5 to 9 degrees AoA at say 400 knots at low altitude would produce so much lift that the wings would tear off. So, could it be possible that the tail plane was not in the postion that the screw jack is indicating, ie that the screw jack had broken loose in one end before impact?

The most likely scenario in my mind, is still some sort of structural failure. Part of the horizontal stab or elevator separating could cause issues, but hard to know to what severity. Another thought would be actuator hardover. Only time will tell for sure

Edit: I guess theoretically a trim runaway leading to a stall could be plausible, although unlikely in my mind.

To get a feel for the time it takes to go through the trim range, here is a video of the 787 trim test.

https://youtu.be/-IlsPnMPYHE

fabian9 wrote:

To get a feel for the time it takes to go through the trim range, here is a video of the 787 trim test.

https://youtu.be/-IlsPnMPYHE

Hard to tell exactly, but if that was full speed then I would guess it would take something like 30 sec from one end to the other.

In the video it takes 33 sec to run to full nose down position, but it dont start from fully nose up, but it also dont run at full speed all the way. So, I think about 30 sec is in the neighbourhood.

If it is the HS jackscrew we see in the video of the wreck, and it is at about 70 percent nose up, and it moves at about the same speed as in the 787 video, then I would say that the jack screw on the 767 must have been broken loose on one end before impact. Othervise it is not enough time to plunge the aircraft and then run the jack screw to 70 percent nose up before impact.

pugman211 wrote:

GEUltraFan9XGTF wrote:

Video of the wreckage found so far:
https://youtu.be/-G-KfcFQg9U

At 4:28 in the video, you can see the jackscrew for the tailplane (I could be wrong though). It's at it's lowest/highest point on the screw? Does that look about right?

If the NTSB suspected mechanical failure, would they really let journalists in the facility where they are storing the recovered parts?

Edited because of incorrect time stamp quoted

It's been interesting because the local Chambers County Sheriff has been extremely media friendly about the entire crash investigation. He's taken multiple reporters out on airboats to see the debris, almost since day one. The video clip from the other day showing the plane in it's final seconds was from a Chambers County Sherrif Dep't, camera. The NTSB asked for it not to be released, but after a few days of pestering by the Sheriff, it was made available to the public. Here is a link to another TV station's reporter who was given access to the warehouse.

https://www.click2houston.com/news/insi ... -warehouse

fabian9 wrote:

To get a feel for the time it takes to go through the trim range, here is a video of the 787 trim test.

https://youtu.be/-IlsPnMPYHE

Obviously, the 787 has the motor and jack mounted opposite to that of the 737 (737 motor mounted on the floor, 787 mounted on the "ceiling"). Does anyone know if the 767 has the assembly mounted like the 787? If so, the damage photos would indicate a trim value closer to 2.5 or 3.0 which for the airspeed they were flying before the upset, I would think is a normal value. Obviously, we don't know the weight distribution of the accident aircraft so any trim number we can assume from the photo is somewhat arbitrary, but if we know it's closer to 2-3 as opposed to 10 or more, that would say something.

adamant365 wrote:

fabian9 wrote:

To get a feel for the time it takes to go through the trim range, here is a video of the 787 trim test.

https://youtu.be/-IlsPnMPYHE

Obviously, the 787 has the motor and jack mounted opposite to that of the 737 (737 motor mounted on the floor, 787 mounted on the "ceiling"). Does anyone know if the 767 has the assembly mounted like the 787? If so, the damage photos would indicate a trim value closer to 2.5 or 3.0 which for the airspeed they were flying before the upset, I would think is a normal value. Obviously, we don't know the weight distribution of the accident aircraft so any trim number we can assume from the photo is somewhat arbitrary, but if we know it's closer to 2-3 as opposed to 10 or more, that would say something.

Ahh, what you say about upside down. That changes the whole picture. If the 767 is like the 787 with the motor on top, then the jack screw is in a nose down position, wouldt you say so?

SteinarN wrote:

adamant365 wrote:

fabian9 wrote:

To get a feel for the time it takes to go through the trim range, here is a video of the 787 trim test.

https://youtu.be/-IlsPnMPYHE

Obviously, the 787 has the motor and jack mounted opposite to that of the 737 (737 motor mounted on the floor, 787 mounted on the "ceiling"). Does anyone know if the 767 has the assembly mounted like the 787? If so, the damage photos would indicate a trim value closer to 2.5 or 3.0 which for the airspeed they were flying before the upset, I would think is a normal value. Obviously, we don't know the weight distribution of the accident aircraft so any trim number we can assume from the photo is somewhat arbitrary, but if we know it's closer to 2-3 as opposed to 10 or more, that would say something.

Ahh, what you say about upside down. That changes the whole picture. If the 767 is like the 787 with the motor on top, then the jack screw is in a nose down position, wouldt you say so?

If I remember correctly, the takeoff range for the 767 is something like 2 - 7 depending on CoG. The lowest value is 0. I'm not sure that the stab can even reach a true "nose down" position, just a minimum or zero nose up. Of course, at low IAS there will be more tendency to pitch the nose down with lower values.

adamant365 wrote:

SteinarN wrote:

adamant365 wrote:

Obviously, the 787 has the motor and jack mounted opposite to that of the 737 (737 motor mounted on the floor, 787 mounted on the "ceiling"). Does anyone know if the 767 has the assembly mounted like the 787? If so, the damage photos would indicate a trim value closer to 2.5 or 3.0 which for the airspeed they were flying before the upset, I would think is a normal value. Obviously, we don't know the weight distribution of the accident aircraft so any trim number we can assume from the photo is somewhat arbitrary, but if we know it's closer to 2-3 as opposed to 10 or more, that would say something.

Ahh, what you say about upside down. That changes the whole picture. If the 767 is like the 787 with the motor on top, then the jack screw is in a nose down position, wouldt you say so?

If I remember correctly, the takeoff range for the 767 is something like 2 - 7 depending on CoG. The lowest value is 0. I'm not sure that the stab can even reach a true "nose down" position, just a minimum or zero nose up. Of course, at low IAS there will be more tendency to pitch the nose down with lower values.

Ok. So you are saying that when the 767 HS is at its nose down limit you might still be able to keep the aircraft level by pulling (hard) on the yoke?
So quite different to the 737 for example where full nose down trim is completely impossible to counter with the elevator?

SteinarN wrote:

adamant365 wrote:

fabian9 wrote:

To get a feel for the time it takes to go through the trim range, here is a video of the 787 trim test.

https://youtu.be/-IlsPnMPYHE

Obviously, the 787 has the motor and jack mounted opposite to that of the 737 (737 motor mounted on the floor, 787 mounted on the "ceiling"). Does anyone know if the 767 has the assembly mounted like the 787? If so, the damage photos would indicate a trim value closer to 2.5 or 3.0 which for the airspeed they were flying before the upset, I would think is a normal value. Obviously, we don't know the weight distribution of the accident aircraft so any trim number we can assume from the photo is somewhat arbitrary, but if we know it's closer to 2-3 as opposed to 10 or more, that would say something.

Ahh, what you say about upside down. That changes the whole picture. If the 767 is like the 787 with the motor on top, then the jack screw is in a nose down position, wouldt you say so?

The B767 stab trim is upside down. The assembly is uppermost, and the shaft points down. Nose up trim (aircraft nose down) is with the nut nearest to the gearbox.
Nose down trim (aircraft nose up) is with lots of thread visible between the gearbox and the nut.

Tristarsteve wrote:

SteinarN wrote:

adamant365 wrote:

Obviously, the 787 has the motor and jack mounted opposite to that of the 737 (737 motor mounted on the floor, 787 mounted on the "ceiling"). Does anyone know if the 767 has the assembly mounted like the 787? If so, the damage photos would indicate a trim value closer to 2.5 or 3.0 which for the airspeed they were flying before the upset, I would think is a normal value. Obviously, we don't know the weight distribution of the accident aircraft so any trim number we can assume from the photo is somewhat arbitrary, but if we know it's closer to 2-3 as opposed to 10 or more, that would say something.

Ahh, what you say about upside down. That changes the whole picture. If the 767 is like the 787 with the motor on top, then the jack screw is in a nose down position, wouldt you say so?

The B767 stab trim is upside down. The assembly is uppermost, and the shaft points down. Nose up trim (aircraft nose down) is with the nut nearest to the gearbox.
Nose down trim (aircraft nose up) is with lots of thread visible between the gearbox and the nut.

Thanks a lot! Then - if it actually is the HS jack screw we see in the video - the jack screw is in a more neutral or nose down position, certainly not in a nose up position.

SteinarN wrote:

Tristarsteve wrote:

SteinarN wrote:

Ahh, what you say about upside down. That changes the whole picture. If the 767 is like the 787 with the motor on top, then the jack screw is in a nose down position, wouldt you say so?

The B767 stab trim is upside down. The assembly is uppermost, and the shaft points down. Nose up trim (aircraft nose down) is with the nut nearest to the gearbox.
Nose down trim (aircraft nose up) is with lots of thread visible between the gearbox and the nut.

Thanks a lot! Then - if it actually is the HS jack screw we see in the video - the jack screw is in a more neutral or nose down position, certainly not in a nose up position.

That would be correct. The apparent position of the assembly in the video should correspond to a trim value that the pilot(s) could overcome with normal control wheel forces. That assumes that the elevators were responding normally, of course.

This quick of an upset followed by rapid transition to an unrecoverable dive just screams mechanical/structural failure, in my amateur opinion. The pros (NTSB) will provide the actual cause, in due time.

And just wanted to add...I can guarantee that barring any nefarious conduct (I seriously doubt this), those pilots were doing everything they could to control it. It's truly a sad and tragic outcome.

khobar95 wrote:

Here is mention of another flight having pitch issues descending through 6,000'. Happened in 2001 and the crew were able to recover, but the NTSB apparently were unable to find a specific cause.

From: https://www.flightglobal.com/news/artic ... ve-456078/

"...the NTSB probed a March 2001 pitch control incident which occurred to an American Airlines 767-300 as it descended through 6,000ft on approach to Paris.

"Its crew found the jet did not respond as expected to control column input, and the pilots resorted to using horizontal stabiliser trim to control pitch.

"US investigators could not find any discrepancies in the stabiliser components – including bellcranks, power control units and shear rivets – and tests suggested the jet might have been affected by water entering the empennage and freezing on the elevator control system. A similar incident had occurred on another 767 during approach to Zurich a month after the American event."

That's really interesting. I don't believe we have discussed this possibility yet.

And yet if the elevator control system was frozen, how did they get nose-down? That's the weird part.

DL_Mech wrote:

MR27122 wrote:

The Egypt Air & the Lauda Air 767's came off the line right after one another & were the last 2 767-3's delivered in 1989 by Boeing.

Am I the only one who saw the year 1989 and immediately looked at the author of the post?

Indeed you're seemingly the only one...even I've no clue what you mean.

mzlin wrote:

khobar95 wrote:

Here is mention of another flight having pitch issues descending through 6,000'. Happened in 2001 and the crew were able to recover, but the NTSB apparently were unable to find a specific cause.

From: https://www.flightglobal.com/news/artic ... ve-456078/

"...the NTSB probed a March 2001 pitch control incident which occurred to an American Airlines 767-300 as it descended through 6,000ft on approach to Paris.

"Its crew found the jet did not respond as expected to control column input, and the pilots resorted to using horizontal stabiliser trim to control pitch.

"US investigators could not find any discrepancies in the stabiliser components – including bellcranks, power control units and shear rivets – and tests suggested the jet might have been affected by water entering the empennage and freezing on the elevator control system. A similar incident had occurred on another 767 during approach to Zurich a month after the American event."

That's really interesting. I don't believe we have discussed this possibility yet.

And yet if the elevator control system was frozen, how did they get nose-down? That's the weird part.

Wouldn't they have noticed a frozen elevator earlier?

What happens if you do have a frozen elevator due to ice, and you are trying very hard to get it to move, and then the ice breaks?

I presume it doesn't move all the way suddenly? And even if it does, wouldn't you just move it back again?

MR27122 wrote:

DL_Mech wrote:

MR27122 wrote:

The Egypt Air & the Lauda Air 767's came off the line right after one another & were the last 2 767-3's delivered in 1989 by Boeing.

Am I the only one who saw the year 1989 and immediately looked at the author of the post?

Indeed you're seemingly the only one...even I've no clue what you mean.

There is a user going by the name of 1989worstyear who waxes lyrical about that year as a point of inflection in aviation, life, the universe and everything. I also had the same reflex as DL Mech on seeing the year written.

V/F

trnswrld wrote:

First of all you’re watching the wrong video. The one with the bubble is the one that’s been modified by the press. Watch the raw video that shows everything as it is. Much easier to view without that moving bubble.

Without the bubble you are too susceptible to being influence by an optical illusion. I went to a video without the bubble and put a paper up against the screen along the path the plane was taking. Any deviation from a straight line was only ever so slight. They were coming in fast and with little deviation to the path. If the crew was attempting to control the plane, it looks like there was very little control. Is it possible to lose all control of the flaps and stabilizers in a 767?

The jackscrew looks to be pretty much at neutral, from working on them.

washingtonflyer wrote:

alggag wrote:

Lrockeagle wrote:

Bout twice as far as Sully did. Idk the glide ratio on a 76 but it’s probably at least 8-1. That would be 9 miles of glide. (Statute miles, I know some of you will argue my math)

Edit: Google says 12:1 per Gimli. So 13.6 miles of glide. May not get you to the airport but it’ll help find somewhere flat to set down, and Houston has a whole lot of flat

Flat land, swamps, even some GA airports would have been in range for a theoretical dead stick landing.

Ellington field is the first thing that comes to mind.

That was my first thought as well although that still would have been a long glide from 7000 ft. Chambers (T00) and Baytown (54T), while not normally suitable for a 767 would have at least been in range instead of a nose dive into the bay. Even the local drag strip is along the way for Gimli Glider 2.0. Plus plenty of flat open fields out in the area.

That said I don’t think fuel starvation or double engine failure were the cause here, just pointing out at that they would of had some options if that’s what had happened.

VirginFlyer wrote:

MR27122 wrote:

DL_Mech wrote:

Am I the only one who saw the year 1989 and immediately looked at the author of the post?

Indeed you're seemingly the only one...even I've no clue what you mean.

There is a user going by the name of 1989worstyear who waxes lyrical about that year as a point of inflection in aviation, life, the universe and everything. I also had the same reflex as DL Mech on seeing the year written.

V/F

Ohh. The statistical probability of an accident in & of itself is fantastically low....2 identical planes that came of the prod line one after the other is nearly an impossibility. I think I read it in the linked article...

https://www.theatlantic.com/magazine/ar ... 90/302332/

trnswrld wrote:

Is that largest piece that he talked about in the corner of the warehouse one of the winglets?

I was thinking the same thing. It does look like the winglet.

Tristarsteve wrote:

The B767 stab trim is upside down. The assembly is uppermost, and the shaft points down. Nose up trim (aircraft nose down) is with the nut nearest to the gearbox.
Nose down trim (aircraft nose up) is with lots of thread visible between the gearbox and the nut.

You have it, it is 'upside down' compared to the 737. Boeing Horizontal Stabilizers have a lot more travel nose up rather than nose down.

MR27122 wrote:

Ohh. The statistical probability of an accident in & of itself is fantastically low....2 identical planes that came of the prod line one after the other is nearly an impossibility.

I must be missing something here.
The odds of any one single aircraft crashing are..... what they are. That is to say, the odds are low, and yet crashes keep happening.

So what are the odds of two planes coming off the production line one after the other both crashing? Note that in the case of the Egyptair and Lauda Air, there is no suggestion that the cause was the same, merely that the line numbers were consecutive. The fact they were both from the same year (1989) goes along with consecutive line numbers. Ditto "identical planes" and "last ones delivered in a particular year". All red herrings. The only connection is an artificial one; consecutive line numbers.

For a start, if the first to crash is line no. 142, then we are looking at either line no 141 or no. 143 in order to make a pair.

Secondly, we are looking for a pair of 707s, or 720s, or 727s, or 737s, or...or... or....
Every separate type of aircraft increases the odds of a pair.

In this instance we have a pair of 767s, and that is relevant because we are discussing Atlas Air 3591.
Conversely, pointing out all the other aircraft types that have not suffered a crash "pair" wouldn't attract the slightest interest - for good reason.

Failing that, here are five other "pairs" from the first aircraft type I looked at.
ATR-42 no.s 083 & 084
ATR-42 no.s 101 & 102
ATR-72 no.s 258 & 259
ATR-72 no.s 458 & 459
ATR-72 no.s 505 & 506
A surprising number of these were ground based DBRs, but still - what are the odds? Quite high apparently.

MR27122 wrote:

DL_Mech wrote:

MR27122 wrote:

The Egypt Air & the Lauda Air 767's came off the line right after one another & were the last 2 767-3's delivered in 1989 by Boeing.

Am I the only one who saw the year 1989 and immediately looked at the author of the post?

Indeed you're seemingly the only one...even I've no clue what you mean.

I think a lot of people actually knew exactly what he meant. The person he was referring to seems to think aircraft design and manufacture prior to 1989 was done by underdeveloped neanderthals using tools made of sticks and stones in a cave with design drawings carved on the walls.

Pbb152 wrote:

I think a lot of people actually knew exactly what he meant. The person he was referring to seems to think aircraft design and manufacture prior to 1989 was done by underdeveloped neanderthals using tools made of sticks and stones in a cave with design drawings carved on the walls.

I maintain that the engineers who used slide rules to do calculations understood the calculations a lot better and by at least a factor of 10 understood significant digits a lot better than engineers, scientists, and mathematicians of the current generation.

An awful lot of slide rule calculated stuff still exists... and filling its design function well.... I suspect that many parts (if not the whole thing) of the 747 was designed using slide rules and not calculators or computers.

Most of the US Nuclear Power Plant fleet was designed using slide rules.

Have a great day,

Well, it is Silly Season on this thread now. Once something more comes from NTSB, it will be more interesting.

I have to say that based on my memory of previous accident investigations, it seems like NTSB is having to dig pretty-deep on this one. They already have had the CVR for a week and the FDR for a little-less than that. The data has been read out, the overall picture of the accident sequence is likely pretty-clear, in terms of broad-brush things said by the crew, what indications were on the instruments, what if any warnings had alerted, what the reported position of the control surfaces was, what the flight path of the aircraft was, what inputs the crew made, etc. There seems to be no evidence in the wreckage of a pre-crash explosion or fire, etc. Usually by now a big-picture analysis has leaked out, but zero.

And usually NTSB will put out a release like the one they did about the CVR -- something the press completely-misinterprets (as they have with the CVR one) but from which we can form a pretty-decent picture of what may have happened, to be refined and defined as the investigation continues. Here, nada so far, which is interesting.

2175301 wrote:

I maintain that the engineers who used slide rules to do calculations understood the calculations a lot better and by at least a factor of 10 understood significant digits a lot better than engineers, scientists, and mathematicians of the current generation.

I maintain that most engineers, scientists, and mathematicians of the current generation understand rationality a lot better than you and by at least a factor of 10 understand the value of evidence-based opinion a lot better than the current generation of uninformed internet posters.

wjcandee wrote:

And usually NTSB will put out a release like the one they did about the CVR -- something the press completely-misinterprets (as they have with the CVR one) but from which we can form a pretty-decent picture of what may have happened, to be refined and defined as the investigation continues. Here, nada so far, which is interesting.

Well, not really. Not to sound insensitive, but it was a cargo accident, and not one that was caught on high quality video (like the Bagram accident), meaning it's had relatively little media coverage compared to a typical passenger airliner accident. The NTSB are not insensitive to public perception, and when people are demanding answers and hundreds of people have loved ones they want explanations for the deaths of, they attempt to provide what information they have. In this case, not many people outside forums like this and the industry itself are demanding that information. So they're putting their heads down and doing their work, as ideally they should. That's how we'll get the final report the fastest.

With the CVR and FDR plus the video that does exist, I doubt the NTSB is going to have that hard of a time piecing this together. They've done more with a lot less. Obviously it's painstaking work in any case, but I don't think it's all that telling that they haven't already released the cause.

wjcandee wrote:

Here, nada so far, which is interesting.

It is.

And it could be due to them just being more careful/thorough/tightlipped this time or that they want to be very sure before releasing anything that is somehow surprising. Or even that they don't know...

Lets review the facts again. Based on videos, the tailplane seems to be in place, or at least not entirely missing. So no catastrophic structural failure. Smaller parts could of course still have gone wrong or missing. And the jackscrew seems to be in reasonable range, so at least it was not stuck at nose down... that still leaves the possibility that runaway trim was missed and they managed to get it back here but not straighten out of the dive. Or that the crew simply was disoriented and run out of time to correct the situation in the few seconds they had. I realise that is in general the most likely cause for any airplane accident, but somehow I have trouble believing this was the reason in this case. And the weather wasn't *that* bad. And no reason to suspect malicious act. No time for fire, fuel starvation, engine problems, etc.

So, what is left is:

- spatial disorientation/confusion while instrument flying, with not enough time to correct when they came lower
- recoverable weather or mechanical event followed by confusion/mistake, leading to not enough time to correct
- structural failure other than losing major parts of the tailplane
- elevator trim runaway, detected while in the air and corrected but not in time to straighten the dive
- control system malfunction outside the jackscrew
- something they don't know yet
- something surprising, e.g., perhaps they now found the EgyptAir accident and the Paris 767 fault? That would be huge.

One piece of the evidence that I'm still intrigued is the bad quality in the CVR. Just bad tech/mikes, high speed of the descent, or something related to the cause of the accident?

Pbb152 wrote:

MR27122 wrote:

DL_Mech wrote:

Am I the only one who saw the year 1989 and immediately looked at the author of the post?

Indeed you're seemingly the only one...even I've no clue what you mean.

I think a lot of people actually knew exactly what he meant. The person he was referring to seems to think aircraft design and manufacture prior to 1989 was done by underdeveloped neanderthals using tools made of sticks and stones in a cave with design drawings carved on the walls.

Hahaha! You made my day

MR27122 wrote:

Ohh. The statistical probability of an accident in & of itself is fantastically low....2 identical planes that came of the prod line one after the other is nearly an impossibility.

19 events of ~1000frames? Either your probability knowledge is poor or your definition of impossible!
With just 2 events the chance is ~0.1%, with each more you are fast in single digit percentage chance.

https://betterexplained.com/articles/un ... y-paradox/