Author Topic: Clues, Documents And Evidence About The Case (Read 1399504 times)

georger · « **Reply #6570 on:** June 30, 2021, 04:20:09 PM »

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Interesting post and exchanges by Ckret etal 2008, on oscillations vs. bump:

Ckret
• 522 posts #4934
November 2, 2008

<Quote Snowmman>

Didn't open the jpg's to look at the report you were referencing, I was speaking to the jump (equipement used and how it would have performed in a higher low opening) which was calculated by a member of the Boeing jump club, of which all were investigated.

The problem with the report is they used the time of the oscillations for the jump, which i think is wrong. i think when you put the whole jump together the oscillations were Cooper slowly moving down the stairs. The bump didn't occur until a few minutes later; when they could see Portland just from the north.

So all of the calculations are correct, just have to move everything south a few minutes.

-----------------------------------------------------

Reply>
In order for something to "oscillate" you have to have some force(s) being applied where a sympathetic frequency is set up. The logical force is the wind, or cross winds. The logical event is the stairs extending into the air stream. But this happens at about 20:12 precisely when they make a left hand turn in the approach to BTGVOR, which changes the angle of the aircraft relative to the wind(s).

So, it is not required that the stairs are being extended further, only that the flight angle of the (plane with stairs) changes with respect to the airstream.

Also there is nothing in the transcript which says the oscillations increased or decreased after they began or if they went away? prior to the bump?

The test which confirmed the bump also confirmed oscillations prior to the bump? And what exactly was "oscillating"

Just an observation -

Georger[/reply]

You are applying too much science, over over analyzing, sometimes the answers are simple. From putting everything together, the crew was referencing the cabin pressure gauge when the statement of “oscillation” was made. Not that they were feeling an oscillation in the aircraft. Remember; in another log created at the same time as the one reporting oscillations the word used was “fluctuations.”

Because the crew always referenced the bump as a pressure change it would make since that prior to the large “Pressure Event,” there were small events leading up.

Now go back and you’re Cooper getting ready to jump. You are gingerly walking down the air stairs because you have never done this before. With each step you take caution, take a step and see what happens, take a step and see what happens. As you are doing this, the cabin pressure gauge in the cockpit starts to fluctuate.

The engineer notices this and reports the anomaly to ops, these fluctuations continue for a few minutes as you figure things out. Once you’re set you jump and the stairs come back to the body of the plane, causing the pressure event known as “the bump.” It is noticeable but not dramatic, the needle instantly spikes, they notice the change in their ears, things calm quickly. Because the small fluctuations continue (the stairs are still open to about 15 degrees) nothing is reported they just assume this is a continuation of what they have already reported. But they do take note, “wonder if he just jumped?” As they wonder this they notice they are just north of the Portland suburbs.

I think the individual typing the teletype was being fed info from the guy keeping the hand written log. When the guy keeping the handwritten log said, “they are reporting some type of fluctuations in the cabin pressure; they said the gauge is bouncing.” The teletype operator then typed “oscillations” his words not the crews.

Amazing how small, even seeming harmless interpretations can cause large fluctuations or oscillations in history.
•

[reply] Georger
This whole scenario is mixing and confusing multiple effects and causes. Vibration of stairs. Trim of aircraft? These are mechanical effects. Then there are acoustic effects being seen on the cabin pressure gauge related to the opening and closing of the hole in the back of the plane. Both effects happening simultaneously but they are separate physical events each with a different cause. The large pressure spike called a 'bump' is an acoustic event due to the sudden closing of the hole by the stair door slamming and closing the rear hole for an instant of time. The crew probably didn't expect that because they had never experienced that happening in a 727 before. The guys dropping cargo in Vietnam may have experienced that - you should check with them? Immediately after the large acoustic pressure spike (door closing) they say the vibrations stopped. That's key! That's the time and place Cooper jumped imo. But there are two separate physical events happening in this oscillations vs bump scenario.
I have been screaming this into the void for months. To underscore this, there is no official record of when the "pressure bump" occurred. The FBI and other researchers conclude that it was the time when the oscillations were last reported. This is wrong-headed.

All we can go on is what the crew has reported anecdotally which is that the lights of the suburbs were coming up and that they hadn't yet crossed the river. You can determine an exact time from those statements. Only broad ranges of time.

What is actually known. The crew reported stair lite on at 19:42. That means the stairs are now free to MOVE. Oscillate, fluctuate, whatever ... but no oscillations are reported until 20:12. According to FJ and his interpretation of the sled test there were no oscillations until AFTER Cooper's weight was off the stairs. According to FJ it was Cooper's weight on the stairs and his leaving the stairs (weight off stairs) that caused oscillations and a pressure spike circa 20:11-12.

Since FJ wont change his argument this matter will sit unsolved - for eternity!

Ckret suggests oscillations and the bump were coterminous with 305's turn at BTG. So maybe FJ and everyone else are wrong!

Chaucer · « **Reply #6571 on:** June 30, 2021, 10:47:31 PM »

The aft stair light may have come on at 7:42, but that doesn’t mean that Cooper began walking out on to the stairs at that point. Cooper on the stairs is what would have begun the oscillations. So, it’s possible Cooper activated the airstairs at 7:42, but did not begin his descent down the stairs until 8:10. As Shutter has pointed out numerous times, the stairs would not have descended on their own, thus they would not be in a position to dramatically affect the aircraft.

FJ, as with many others, confuse the oscillations with the final pressure bump. Yes, they are connected, but they represent two different things. You cannot use the oscillations to pinpoint a jump time.

I do think Carr’s theory about the change in plane direction is interesting and requires more investigation.

georger · « **Reply #6572 on:** June 30, 2021, 11:31:42 PM »

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The aft stair light may have come on at 7:42, but that doesn’t mean that Cooper began walking out on to the stairs at that point. Cooper on the stairs is what would have begun the oscillations. So, it’s possible Cooper activated the airstairs at 7:42, but did not begin his descent down the stairs until 8:10. As Shutter has pointed out numerous times, the stairs would not have descended on their own, thus they would not be in a position to dramatically affect the aircraft.

FJ, as with many others, confuse the oscillations with the final pressure bump. Yes, they are connected, but they represent two different things. You cannot use the oscillations to pinpoint a jump time.

I do think Carr’s theory about the change in plane direction is interesting and requires more investigation.

7:42 is important for two obvious reasons: (a) the stair seal of the aircraft is now open even though the plane was flying unpressurised. Air flow now occurs between the cabin and the outside world. (b) the stair lock is off - stairs are now free to oscillate-shake-vibrate-fall lower- whatever. With the stair unlocked both mechanical and acoustic artifacts can now happen ... and they did. The TAG Team test proved that.

FJ says oscillations and bump are the same thing - mechanical vibration. He says the bump was merely the largest (last) of all of the vibrations. He says all oscillations and bump happened AFTER Cooper's weight was off the stairs; and there were no oscillations before that! (he may back off and retract or deny he said that!). FJ's theory does not distinguish mechanical from acoustic-air pressure artifacts. Others think the bump was an acoustic event due to the stairs slamming shut sealing the door hole (in rebound after weight is taken off the stairs as Cooper jumps). Anderson said his instruments registered/measured 'air pressure changes in cabin pressure', not mechanical vibrations. Mechanical vibration alone does not account for or cause a 'pressure' event in the cabin 'we all felt in our ears'!

Yes. Carr's question about the BTG turn is interesting...

** FJ's theory fails to distinguish mechanical vs acoustic events involving the stairs. FJ even fails to tell us what his oscillations derive from! Anderson makes it abundantly clear the bump was an acoustic pressure event recorded on his 'cabin pressure gauge' and 'felt in the ears'! Thats an acoustic event; not a mechanical event.

Robert99 · « **Reply #6573 on:** July 01, 2021, 02:35:12 AM »

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The aft stair light may have come on at 7:42, but that doesn’t mean that Cooper began walking out on to the stairs at that point. Cooper on the stairs is what would have begun the oscillations. So, it’s possible Cooper activated the airstairs at 7:42, but did not begin his descent down the stairs until 8:10. As Shutter has pointed out numerous times, the stairs would not have descended on their own, thus they would not be in a position to dramatically affect the aircraft.

FJ, as with many others, confuse the oscillations with the final pressure bump. Yes, they are connected, but they represent two different things. You cannot use the oscillations to pinpoint a jump time.

I do think Carr’s theory about the change in plane direction is interesting and requires more investigation.

7:42 is important for two obvious reasons: (a) the stair seal of the aircraft is now open even though the plane was flying unpressurised. Air flow now occurs between the cabin and the outside world. (b) the stair lock is off - stairs are now free to oscillate-shake-vibrate-fall lower- whatever. With the stair unlocked both mechanical and acoustic artifacts can now happen ... and they did. The TAG Team test proved that.

FJ says oscillations and bump are the same thing - mechanical vibration. He says the bump was merely the largest (last) of all of the vibrations. He says all oscillations and bump happened AFTER Cooper's weight was off the stairs; and there were no oscillations before that! (he may back off and retract or deny he said that!). FJ's theory does not distinguish mechanical from acoustic-air pressure artifacts. Others think the bump was an acoustic event due to the stairs slamming shut sealing the door hole (in rebound after weight is taken off the stairs as Cooper jumps). Anderson said his instruments registered/measured 'air pressure changes in cabin pressure', not mechanical vibrations. Mechanical vibration alone does not account for or cause a 'pressure' event in the cabin 'we all felt in our ears'!

Yes. Carr's question about the BTG turn is interesting...

** FJ's theory fails to distinguish mechanical vs acoustic events involving the stairs. FJ even fails to tell us what his oscillations derive from! Anderson makes it abundantly clear the bump was an acoustic pressure event recorded on his 'cabin pressure gauge' and 'felt in the ears'! Thats an acoustic event; not a mechanical event.

Georger, Chaucer, and Carr (if you see this):

The turn at the Malay Intersection (Toledo area) toward the Battleground VORTAC (then known as the Portland VORTAC), took place at about 8:00PM.

I am not able to decipher exactly what Carr means or is getting at when he discusses the wind or slipstream, but I get the impression that he is confusing the wind over the aircraft with the wind over the ground.

The wind over the aircraft does not change regardless of the direction the aircraft is headed. And the direction that the aircraft is headed, relative to the winds aloft, has only a very minimal effect on Cooper's descent whether as a no-pull or under a canopy.

Chaucer and I discussed this at length some time back. So take a look at those posts if you want more information on this point.

Chaucer · « **Reply #6574 on:** July 01, 2021, 10:04:00 AM »

Carr’s not referring to the turn at Malay. He’s referring to the turn that the plane took between Battleground and Orchards. Still, what effect the turn would have on the winds is something I don’t know. I’ll trust the opinion of experts like Shuttler and Bob.

Chaucer · « **Reply #6575 on:** July 01, 2021, 12:05:36 PM »

In discussing this with Flyjack, the crux of his argument rests in the belief that the oscillations and the pressure bump are the same thing and when the crew reported the “oscillations” or “pressure fluctuations” they were also reporting the final pressure bump. I’m certain that this belief is contradicted by Anderson’s statements and by the sled test.

I believe these were two distinct things and that only the first thing - the oscillations -were reported. The pressure bump is not reported anywhere in the record. To conflate these two things is a convenient, but wrong, way to support a jump at 8:10/8:11.

georger · « **Reply #6576 on:** July 01, 2021, 03:41:59 PM »

I am probably the only one here who has taught 'acoustic physics' as a course requirement for certain majors, at the college level.

FJ has been forced to retract and back up, as I predicted he would, after I brought up the physics of the stairs involved in this case. FJ had previously said: “The sled test showed that the oscillations/fluctuations INCREASED AFTER the weight left the stairs NOT BEFORE.” Today FJ now says: "There were minor oscillations/bumps on the gauge for some time PRIOR to the 8:10/11 report of oscillations,, they were reporting an increase in the cabin." FJ's concession is of no importance to me. Almost everyone else seems to understand the basics of what happened with the stairs and why, starting clear back at 19:42 up until the moment Cooper separated from the stairs and left the plane. It's unfortunate someone did not go to the back and check to see if Cooper and his socalled bomb were gone (as ground control suggested they do!). Why fly all the way to Reno under the threat of being blown up at any moment?

The manner in which Cooper deployed from the stairs has been questioned by many. Did he go all the way down and jump off the end of the stairs, did he pull his chute while standing in the middle of the stairs, etc? Each different choice of deployment would probably produce different measurable effects. The TAG team techs installed various instrumentation for their tests - Anderson manned his station at the cabin pressure gauge in the cockpit. Several sleds were dropped by sliding them down the stairs until they dropped off of the end of the stairs. These tests apparently made no attempt to qualitatively differentiate different deployments from the stairs. My guess is different deployments would produce slightly different measurable effects with respect to oscillations/vibrations/pressure bumps or spikes measured by the cabin pressure gauge. My guess is the large pressure spike experienced by Anderson and the crew matches a deployment from the bottom of the stairs vs other deployment choices. My guess is the 'magnitude' of the pressure spike experienced during the hijacking matches deployment from the bottom of the stairs, stairs then swinging back full force against the stair opening vs. smaller magnitudes of pressure affect that other deployment options might have produced.

I doubt that Cooper stood in the middle of the stairs and simply pulled his chute. I doubt the large pressure effect experienced is related to that scenario.

dudeman17 · « **Reply #6577 on:** July 01, 2021, 06:42:31 PM »

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The wind over the aircraft does not change regardless of the direction the aircraft is headed.

Well, yeah, but... During the actual turn, the wind over the aircraft would change. Indeed, changing the angle of attack of the airframe to the relative wind is what makes the turn happen. And that might well affect what the door/stairs is doing. Again, during the actual turn. Once the aircraft returns to straight and level flight, that effect would cease.

It would be helpful if there was moving film of the sled tests available. How freely the stairs moved would be a big factor (as opposed to how much that movement might be dampened by the pressure of the hydraulic system). It would seem that the stairs on Cooper's plane moved more freely than the ones on the plane in the Treat Williams movie. When that guy jumps (as I recall it), those stairs don't move that much.

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It's unfortunate someone did not go to the back and check to see if Cooper and his socalled bomb were gone (as ground control suggested they do!). Why fly all the way to Reno under the threat of being blown up at any moment?

They might have been afraid to. If they thought he had left, but weren't sure... If someone went back there and it turned out that he had not left, that might have pissed him off.

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The manner in which Cooper deployed from the stairs has been questioned by many. Did he go all the way down and jump off the end of the stairs, did he pull his chute while standing in the middle of the stairs, etc? Each different choice of deployment would probably produce different measurable effects. The TAG team techs installed various instrumentation for their tests - Anderson manned his station at the cabin pressure gauge in the cockpit. Several sleds were dropped by sliding them down the stairs until they dropped off of the end of the stairs. These tests apparently made no attempt to qualitatively differentiate different deployments from the stairs. My guess is different deployments would produce slightly different measurable effects with respect to oscillations/vibrations/pressure bumps or spikes measured by the cabin pressure gauge. My guess is the large pressure spike experienced by Anderson and the crew matches a deployment from the bottom of the stairs vs other deployment choices. My guess is the 'magnitude' of the pressure spike experienced during the hijacking matches deployment from the bottom of the stairs, stairs then swinging back full force against the stair opening vs. smaller magnitudes of pressure affect that other deployment options might have produced.

I doubt that Cooper stood in the middle of the stairs and simply pulled his chute. I doubt the large pressure effect experienced is related to that scenario.

I would agree with that.

Robert99 · « **Reply #6578 on:** July 01, 2021, 07:33:21 PM »

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The wind over the aircraft does not change regardless of the direction the aircraft is headed.

Well, yeah, but... During the actual turn, the wind over the aircraft would change. Indeed, changing the angle of attack of the airframe to the relative wind is what makes the turn happen. And that might well affect what the door/stairs is doing. Again, during the actual turn. Once the aircraft returns to straight and level flight, that effect would cease.

Keep in mind that they were doing very gentle turns, not even at a standard two-minute turn rate. In fact, there is no evidence that they even turned a total of 360 degrees until they had to break off the initial approach to Reno and circle around to land. So during the entire flight from Seattle to Reno they may not have turned more than 720 degrees total (equivalent to two complete circles). In my opinion, the airflow change over the rear part of the fuselage and the stairs would be absolutely minimal during these turns.

The flight crew told the Oakland ATC controller that they had problems when descending and that is apparently the problem that caused the circling at Reno. And that problem was probably due to the aircraft configuration specified by Cooper.

Chaucer · « **Reply #6579 on:** July 01, 2021, 07:55:09 PM »

Yes, while the FBI flight path shows sharp turns based on connecting the dots, this wouldn’t have actually been the case. That said, with the aft stairs down and the plane banking into the wind, what kind of effect would that have had on the plane?

Robert99 · « **Reply #6580 on:** July 01, 2021, 11:34:08 PM »

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Yes, while the FBI flight path shows sharp turns based on connecting the dots, this wouldn’t have actually been the case. That said, with the aft stairs down and the plane banking into the wind, what kind of effect would that have had on the plane?

Chaucer, You are missing the point completely! The plane was not "banking into the wind"! The plane didn't have the slightest idea where the winds aloft were coming from. Again, and again, and again, you have got to understand that once the airplane gets off the ground and out of the ground effect the aerodynamics of the airplane are independent of the winds regardless of whether they are the ground winds or the winds aloft.

But the winds aloft must be considered in the navigation of the airplane.

georger · « **Reply #6581 on:** July 01, 2021, 11:43:31 PM »

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The wind over the aircraft does not change regardless of the direction the aircraft is headed.

Well, yeah, but... During the actual turn, the wind over the aircraft would change. Indeed, changing the angle of attack of the airframe to the relative wind is what makes the turn happen. And that might well affect what the door/stairs is doing. Again, during the actual turn. Once the aircraft returns to straight and level flight, that effect would cease.

It would be helpful if there was moving film of the sled tests available. How freely the stairs moved would be a big factor (as opposed to how much that movement might be dampened by the pressure of the hydraulic system). It would seem that the stairs on Cooper's plane moved more freely than the ones on the plane in the Treat Williams movie. When that guy jumps (as I recall it), those stairs don't move that much.

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It's unfortunate someone did not go to the back and check to see if Cooper and his socalled bomb were gone (as ground control suggested they do!). Why fly all the way to Reno under the threat of being blown up at any moment?

They might have been afraid to. If they thought he had left, but weren't sure... If someone went back there and it turned out that he had not left, that might have pissed him off.

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The manner in which Cooper deployed from the stairs has been questioned by many. Did he go all the way down and jump off the end of the stairs, did he pull his chute while standing in the middle of the stairs, etc? Each different choice of deployment would probably produce different measurable effects. The TAG team techs installed various instrumentation for their tests - Anderson manned his station at the cabin pressure gauge in the cockpit. Several sleds were dropped by sliding them down the stairs until they dropped off of the end of the stairs. These tests apparently made no attempt to qualitatively differentiate different deployments from the stairs. My guess is different deployments would produce slightly different measurable effects with respect to oscillations/vibrations/pressure bumps or spikes measured by the cabin pressure gauge. My guess is the large pressure spike experienced by Anderson and the crew matches a deployment from the bottom of the stairs vs other deployment choices. My guess is the 'magnitude' of the pressure spike experienced during the hijacking matches deployment from the bottom of the stairs, stairs then swinging back full force against the stair opening vs. smaller magnitudes of pressure affect that other deployment options might have produced.

I doubt that Cooper stood in the middle of the stairs and simply pulled his chute. I doubt the large pressure effect experienced is related to that scenario.

I would agree with that.

Good post - thanks! Somewhere there is a photo of an instrument(s) TAG techs attached at the top of the stairs to measure pressure at the door? Anyone have that photo? Did that instrument record vibrations and a bump(s) in addition to Anderson at the engineer's chair? What was the instrument? Likewise FDR record of pressure changes? ** I may have something on this in my Hominid files since Hom interviewed Wally etc... I will check.

Im willing to bet Boeing knew all about 'vibrations and bumps' with regard to their stairs; during their development program. I have not seen any document which references Boeing being consulted in this matter ? We know Boeing researched drops being conducted with the 727. They probably had files on vibrations/bumps in countless configurations. Maybe our esteemed colleague FLY JACK can do a search ...

georger · « **Reply #6582 on:** July 01, 2021, 11:57:12 PM »

Photo found! Instrument circled was installed by a TAG team tech (NWA tech) to measure ..................... what? Did this instrument make a record of any kind?

Chaucer · « **Reply #6583 on:** July 01, 2021, 11:59:20 PM »

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Yes, while the FBI flight path shows sharp turns based on connecting the dots, this wouldn’t have actually been the case. That said, with the aft stairs down and the plane banking into the wind, what kind of effect would that have had on the plane?

Chaucer, You are missing the point completely! The plane was not "banking into the wind"! The plane didn't have the slightest idea where the winds aloft were coming from. Again, and again, and again, you have got to understand that once the airplane gets off the ground and out of the ground effect the aerodynamics of the airplane are independent of the winds regardless of whether they are the ground winds or the winds aloft.

But the winds aloft must be considered in the navigation of the airplane.

After Battleground the plane turned to the southwest - into the SE winds. That's all I'm saying.

georger · « **Reply #6584 on:** July 02, 2021, 12:03:25 AM »

Blk and white version of the stairwell instrument - TAG test. What did these three instruments measure?

Poll

Do you believe Cooper lived or died. the option are below to cast a vote...

Author Topic: Clues, Documents And Evidence About The Case (Read 1399504 times)

georger

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Chaucer

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georger

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Robert99

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Chaucer

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Chaucer

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georger

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dudeman17

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Robert99

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georger

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