Poll

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

0% Cooper lived
6 (9.7%)
25% Cooper lived
4 (6.5%)
35% Cooper lived.
2 (3.2%)
50% Cooper lived
13 (21%)
75% Cooper lived
14 (22.6%)
100 Cooper lived
23 (37.1%)

Total Members Voted: 57

Author Topic: Clues, Documents And Evidence About The Case  (Read 787723 times)

Offline Robert99

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Re: Clues, Documents And Evidence About The Case
« Reply #7995 on: August 09, 2022, 04:04:01 PM »
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I have no doubt that surface lights are visible from 10 or even 30,000 feet. I guess my question would be: assuming the jump happened at 8:11 +/- ~1 minute, would Rataczak have been able to look out the window and say "that looks like the suburbs of Portland" or the "immediate vicinity of Portland"? That's a minimum of 10 miles from condensed surface light TODAY, let alone 50 years ago. 

I suppose it's possible...

The flight crew would know their location and would know where that glow coming through the clouds originated.
 

Offline Robert99

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Re: Clues, Documents And Evidence About The Case
« Reply #7996 on: August 09, 2022, 04:09:23 PM »
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Under the conditions that existed on November 24, 1971, Rataczak, Scott, and Anderson would be able to see the glow from the lights in the Portland/Vancouver area from some distance away.  The visibility on the ground at Portland International Airport was reported as about 10+ miles (it was not exactly measured and was probably greater) and the visibility between cloud layers was probably about the same.

I lived in the Phoenix area for quite a few years and the visibility at Sky Harbor Airport was typically given as 10 miles.  But on those days with 10 miles of visibility, I could typically see 40, 50, or 60 miles while driving down the freeway.
Interesting. That certainly would give them a general area, but hardly anything specific.

What do you mean by that?
 

Offline Robert99

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Re: Clues, Documents And Evidence About The Case
« Reply #7997 on: August 09, 2022, 04:12:14 PM »
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Persistent pesky questions about them stairs and the oscillations and bump...

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...going down a couple of steps past that hinge point is going to lower the stairs enough to create pressure changes in the cabin that would be noticeable in the cockpit cabin altitude instrument...     ...this time, he goes way down the steps as far as he can, perhaps to the very end of the stairs, and jumps.  Cooper's weight on the stairs will not lower them to the same degree as they are lowered on the ground.  But when Cooper steps off those stairs they slam up into their closed position but don't lock there...     

In that clip from the Treat Williams movie, when the stunt guy jumps off the stairs, they retract very slightly and slowly. They certainly don't 'slam' shut, even momentarily. I would imagine the pilot could feel a bit of change on the pitch influence, but I don't see it re-sealing the cabin momentarily and causing a pressure event. For the stairs to behave in the way described, I would guess that Cooper would have to have pulled the emergency release, which should disconnect them from the hydraulic system and allow them to free-float. But I'm told that did not happen, that he did not pull the emergency release. So would there be that much variable from plane to plane, how much the stair door would be able to move while still connected to (dampened by) the hydraulic system?  ...??

I'll leave an explanation of the aft stairs hydraulic system to others, but the drop tests prove the point about the bump and cabin pressure oscillations.
 

Offline Chaucer

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Re: Clues, Documents And Evidence About The Case
« Reply #7998 on: August 09, 2022, 04:15:49 PM »
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Under the conditions that existed on November 24, 1971, Rataczak, Scott, and Anderson would be able to see the glow from the lights in the Portland/Vancouver area from some distance away.  The visibility on the ground at Portland International Airport was reported as about 10+ miles (it was not exactly measured and was probably greater) and the visibility between cloud layers was probably about the same.

I lived in the Phoenix area for quite a few years and the visibility at Sky Harbor Airport was typically given as 10 miles.  But on those days with 10 miles of visibility, I could typically see 40, 50, or 60 miles while driving down the freeway.
Interesting. That certainly would give them a general area, but hardly anything specific.

What do you mean by that?
If they saw the glow of lights of Portland from a distance - say a standard 10 miles - they would have a general idea of their location, but would not be able to pinpoint on a map their exact location from the lights alone.
“Completely unhinged”
 

Offline Robert99

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Re: Clues, Documents And Evidence About The Case
« Reply #7999 on: August 09, 2022, 04:15:59 PM »
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Persistent pesky questions about them stairs and the oscillations and bump...

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...going down a couple of steps past that hinge point is going to lower the stairs enough to create pressure changes in the cabin that would be noticeable in the cockpit cabin altitude instrument...     ...this time, he goes way down the steps as far as he can, perhaps to the very end of the stairs, and jumps.  Cooper's weight on the stairs will not lower them to the same degree as they are lowered on the ground.  But when Cooper steps off those stairs they slam up into their closed position but don't lock there...     

In that clip from the Treat Williams movie, when the stunt guy jumps off the stairs, they retract very slightly and slowly. They certainly don't 'slam' shut, even momentarily. I would imagine the pilot could feel a bit of change on the pitch influence, but I don't see it re-sealing the cabin momentarily and causing a pressure event. For the stairs to behave in the way described, I would guess that Cooper would have to have pulled the emergency release, which should disconnect them from the hydraulic system and allow them to free-float. But I'm told that did not happen, that he did not pull the emergency release. So would there be that much variable from plane to plane, how much the stair door would be able to move while still connected to (dampened by) the hydraulic system?  ...??
I don't have a good answer for that either. I have heard different things - the stairs hydraulics were not deployed and the stairs were freefloating and vice versa. Regardless, it seems that the pressure bump was simulated during the drop test in January 1972.

Here is what I do know:  the cabin rate of climb and descent gauge uses a sensor in the cabin to measure cabin pressure altitude. During an unpressurized flight - like the Cooper hijacking for example - it will read approximately the altitude that the aircraft is at. It will respond just like the flight altimeter - going up and down with the aircraft.

I propose that the 727 was experiencing what's known as a phugoid.

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If the plane was experiencing a phugoid, that would be reflected as oscillations in the cabin rate of climb indicator. I think the slow extension of the airstairs by Cooper caused phugoid oscillations in the aircraft that the crew noticed on the gauges. When Cooper jumped, the crew experienced a pressure bump - a rather well-known phenomenon in aviation when the pressure of the cabin increases dramatically - that usually causes your ears to "pop". When that happened, the airstairs were no longer descending and the aircraft stabilized from its phugoid.

Thus, while both phenomena - the phugoid oscillations and the pressure bump - were caused by Cooper's behavior on the airstairs, they were distinct things. Whether the crew, the airline flight ops, or the FBI understood the difference when it happened or immediately after is the question.

Chaucer, as an aeronautical engineer my main time was in flight dynamics which included aircraft performance and stability and control.  Longitudinal aircraft stability involves a short period mode and a longer mode called the phugoid.

The short period mode is typically completely damped out within a couple of seconds and is not generally noticeable to the pilot.  I have never noticed anything that I could identify as the short period mode in flying powered general aviation aircraft and unpowered sailplanes.

I have more than 1000 hours of flying time in unpowered sailplanes which spend about 90 percent or more of their time in maneuvering flight.  Consequently, for sailplanes, it is desired that the longitudinal stability be essentially zero.  This means that when the pilot takes his hand off the stick the sailplane will diverge longitudinal as well as about the other two axes.  Longitudinally, this divergence is the phugoid and it will never dampen itself out.  Without corrections by the pilot the sailplane will end up in a spiral and if it stalls it will spin.  Long flights in sailplanes can be very tiring.  My longest flight sailplane flight was about 7 hours and 20 minutes.  After landing, it took me at least 5 minutes to get out of the cockpit and stand up and I felt lousy the next day.

Powered aircraft, even fighter aircraft, generally spend about 90 percent or more of their time in straight and level flight.  Again, the short period mode dampens out in only a few seconds.  But the phugoid mode may take 4, 5, 6, or more minutes, repeat minutes, to dampen out naturally if it ever does so.  Hand flying early jet airliners at high altitudes was particularly tiring for the pilots due to the phugoid.  Consequently, the autopilots were typically activated as soon as possible after takeoff and stayed on until the descent for landing.
Flying a sailplane sounds like fun. Too bad I'm a nervous flyer. Go figure.

Quote
But the phugoid simply cannot explain the cabin pressure altitude oscillations or the bump when the stairs hit the fuselage when Cooper jumped.  It is just not possible.
First, in my post I said that the phugoid would explain the cabin pressure oscillations, but NOT the bump. The bump, I think as has been clearly shown, is caused by the door swinging back up after Cooper jumped.

Second, since this would appear to be your area of expertise, I would hope you could explain why a phugoid mode can't explain the oscillations in the cabin pressure rate of climb. I may be wrong about it, and I only offered it up as a possibility. At its face, it appears to make sense. Rather than simply tell me it's not possible, tell me why.

Simple.  The autopilot or the pilot hand flying the aircraft would cancel out the phugoid and it would not be a factor in the cabin pressure oscillations.

This is not an insult.
 

Offline Robert99

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Re: Clues, Documents And Evidence About The Case
« Reply #8000 on: August 09, 2022, 04:28:06 PM »
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Under the conditions that existed on November 24, 1971, Rataczak, Scott, and Anderson would be able to see the glow from the lights in the Portland/Vancouver area from some distance away.  The visibility on the ground at Portland International Airport was reported as about 10+ miles (it was not exactly measured and was probably greater) and the visibility between cloud layers was probably about the same.

I lived in the Phoenix area for quite a few years and the visibility at Sky Harbor Airport was typically given as 10 miles.  But on those days with 10 miles of visibility, I could typically see 40, 50, or 60 miles while driving down the freeway.
Interesting. That certainly would give them a general area, but hardly anything specific.

What do you mean by that?
If they saw the glow of lights of Portland from a distance - say a standard 10 miles - they would have a general idea of their location, but would not be able to pinpoint on a map their exact location from the lights alone.

To determine their location all the flight crew had to do was look at their instruments.  They had two VORTAC receivers, two DME receivers, and two ADF receivers and were supposedly tracking down V-23.  The VORTAC receivers would give them their lateral position to within less than a mile and the DME receivers would give them their longitudinal position to well less than a mile.  Their onboard navigation information was more accurate than any radar information.
 

Offline Chaucer

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Re: Clues, Documents And Evidence About The Case
« Reply #8001 on: August 09, 2022, 04:29:46 PM »
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Persistent pesky questions about them stairs and the oscillations and bump...

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...going down a couple of steps past that hinge point is going to lower the stairs enough to create pressure changes in the cabin that would be noticeable in the cockpit cabin altitude instrument...     ...this time, he goes way down the steps as far as he can, perhaps to the very end of the stairs, and jumps.  Cooper's weight on the stairs will not lower them to the same degree as they are lowered on the ground.  But when Cooper steps off those stairs they slam up into their closed position but don't lock there...     

In that clip from the Treat Williams movie, when the stunt guy jumps off the stairs, they retract very slightly and slowly. They certainly don't 'slam' shut, even momentarily. I would imagine the pilot could feel a bit of change on the pitch influence, but I don't see it re-sealing the cabin momentarily and causing a pressure event. For the stairs to behave in the way described, I would guess that Cooper would have to have pulled the emergency release, which should disconnect them from the hydraulic system and allow them to free-float. But I'm told that did not happen, that he did not pull the emergency release. So would there be that much variable from plane to plane, how much the stair door would be able to move while still connected to (dampened by) the hydraulic system?  ...??
I don't have a good answer for that either. I have heard different things - the stairs hydraulics were not deployed and the stairs were freefloating and vice versa. Regardless, it seems that the pressure bump was simulated during the drop test in January 1972.

Here is what I do know:  the cabin rate of climb and descent gauge uses a sensor in the cabin to measure cabin pressure altitude. During an unpressurized flight - like the Cooper hijacking for example - it will read approximately the altitude that the aircraft is at. It will respond just like the flight altimeter - going up and down with the aircraft.

I propose that the 727 was experiencing what's known as a phugoid.

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If the plane was experiencing a phugoid, that would be reflected as oscillations in the cabin rate of climb indicator. I think the slow extension of the airstairs by Cooper caused phugoid oscillations in the aircraft that the crew noticed on the gauges. When Cooper jumped, the crew experienced a pressure bump - a rather well-known phenomenon in aviation when the pressure of the cabin increases dramatically - that usually causes your ears to "pop". When that happened, the airstairs were no longer descending and the aircraft stabilized from its phugoid.

Thus, while both phenomena - the phugoid oscillations and the pressure bump - were caused by Cooper's behavior on the airstairs, they were distinct things. Whether the crew, the airline flight ops, or the FBI understood the difference when it happened or immediately after is the question.

Chaucer, as an aeronautical engineer my main time was in flight dynamics which included aircraft performance and stability and control.  Longitudinal aircraft stability involves a short period mode and a longer mode called the phugoid.

The short period mode is typically completely damped out within a couple of seconds and is not generally noticeable to the pilot.  I have never noticed anything that I could identify as the short period mode in flying powered general aviation aircraft and unpowered sailplanes.

I have more than 1000 hours of flying time in unpowered sailplanes which spend about 90 percent or more of their time in maneuvering flight.  Consequently, for sailplanes, it is desired that the longitudinal stability be essentially zero.  This means that when the pilot takes his hand off the stick the sailplane will diverge longitudinal as well as about the other two axes.  Longitudinally, this divergence is the phugoid and it will never dampen itself out.  Without corrections by the pilot the sailplane will end up in a spiral and if it stalls it will spin.  Long flights in sailplanes can be very tiring.  My longest flight sailplane flight was about 7 hours and 20 minutes.  After landing, it took me at least 5 minutes to get out of the cockpit and stand up and I felt lousy the next day.

Powered aircraft, even fighter aircraft, generally spend about 90 percent or more of their time in straight and level flight.  Again, the short period mode dampens out in only a few seconds.  But the phugoid mode may take 4, 5, 6, or more minutes, repeat minutes, to dampen out naturally if it ever does so.  Hand flying early jet airliners at high altitudes was particularly tiring for the pilots due to the phugoid.  Consequently, the autopilots were typically activated as soon as possible after takeoff and stayed on until the descent for landing.
Flying a sailplane sounds like fun. Too bad I'm a nervous flyer. Go figure.

Quote
But the phugoid simply cannot explain the cabin pressure altitude oscillations or the bump when the stairs hit the fuselage when Cooper jumped.  It is just not possible.
First, in my post I said that the phugoid would explain the cabin pressure oscillations, but NOT the bump. The bump, I think as has been clearly shown, is caused by the door swinging back up after Cooper jumped.

Second, since this would appear to be your area of expertise, I would hope you could explain why a phugoid mode can't explain the oscillations in the cabin pressure rate of climb. I may be wrong about it, and I only offered it up as a possibility. At its face, it appears to make sense. Rather than simply tell me it's not possible, tell me why.

Simple.  The autopilot or the pilot hand flying the aircraft would cancel out the phugoid and it would not be a factor in the cabin pressure oscillations.

This is not an insult.
I certainly think if the autopilot was on, then a phugoid would be easily dampened. I don't think the autopilot was on.

With that said, would flying unpressurized at night through clouds with little frame of reference, impact the ability of the pilot to detect a phugoid and thereby react to it? Rataczak obviously had a lot of other things to be distracted about.

I'm not arguing strongly in favor of a phugoid. I'm sincerely asking. If it's not possible, then it's not possible.
“Completely unhinged”
 

Offline Chaucer

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Re: Clues, Documents And Evidence About The Case
« Reply #8002 on: August 09, 2022, 04:31:32 PM »
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Under the conditions that existed on November 24, 1971, Rataczak, Scott, and Anderson would be able to see the glow from the lights in the Portland/Vancouver area from some distance away.  The visibility on the ground at Portland International Airport was reported as about 10+ miles (it was not exactly measured and was probably greater) and the visibility between cloud layers was probably about the same.

I lived in the Phoenix area for quite a few years and the visibility at Sky Harbor Airport was typically given as 10 miles.  But on those days with 10 miles of visibility, I could typically see 40, 50, or 60 miles while driving down the freeway.
Interesting. That certainly would give them a general area, but hardly anything specific.

What do you mean by that?
If they saw the glow of lights of Portland from a distance - say a standard 10 miles - they would have a general idea of their location, but would not be able to pinpoint on a map their exact location from the lights alone.

To determine their location all the flight crew had to do was look at their instruments.  They had two VORTAC receivers, two DME receivers, and two ADF receivers and were supposedly tracking down V-23.  The VORTAC receivers would give them their lateral position to within less than a mile and the DME receivers would give them their longitudinal position to well less than a mile.  Their onboard navigation information was more accurate than any radar information.
That's not what Rataczak told Bruce Smith in his book:

"Flight 305 didn't have the capacity to determine its exact location. Only the air traffic controllers could determine our position."
“Completely unhinged”
 

Offline Olemisscub

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Re: Clues, Documents And Evidence About The Case
« Reply #8003 on: August 09, 2022, 08:07:42 PM »
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Where do we get that Cooper was even wearing a parachute when Tina last saw him? Is that from Tosaw's interview or something? Unless I'm mistaken and I've read them many times recently, neither of her FBI interviews mention her seeing him actually wearing a chute. Just trying to figure out if the last time she saw him whether or not he had put on his chute yet. We all seem to assume that I'm struggling to actually find that.

Tina gave a statement to the FBI that she saw Cooper put on one of the backpack parachutes like he knew what he was doing.  This was while the airliner was still on the ground at SEATAC.  Tina's comments were documented very early in the investigation.

When Cooper told Tina that she could go to the cockpit, just a few minutes after the takeoff from SEATAC, he also told her to close the curtain between the first class and rear portion of the cabin.  As Tina was closing that curtain, she had her last look at Cooper and stated that he was tieing some of the shroud lines from the reserve pack that was left on the aircraft around his waist.  This can only mean that Cooper still had on the parachute and that it was over his raincoat.


Yes, I'm referring to her two interviews in the 302's. I've read them many, many times. She appears to mention nothing about him actually wearing a parachute in those two FBI interviews. She says he was "completely familiar with the parachutes he was given."

I'm also not going to assume that he's wearing his parachute when he's tying this crap to himself. She says in the interview that "the last time she saw him he had a nylon cord tied around his waist and was standing in the aisle."

Am I missing something in one of her FBI interviews where she says that she saw Cooper put on the parachute? If someone could point out to me where she says that I'd appreciate it.

My assumption would be that if he's still tying things around his waist the last time she sees him then perhaps he wasn't wearing his chute at that point. Wouldn't it be a little cumbersome to be wrapping things around your waist while wearing a bulky NB-8? I mean...I think I'd like my parachute pack to have an unencumbered opening.

The "complete familiarity" she's referring to might have been with how he knew where everything was on the parachutes when he was cannibalizing them and his dismissal of the instructions, etc.

I've just been reading her interviews a bunch lately and I was struck by the fact that she never seems to mention him actually putting on his chute unless I've missed it somehow.
« Last Edit: August 09, 2022, 08:12:10 PM by Olemisscub »
 

Offline Robert99

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Re: Clues, Documents And Evidence About The Case
« Reply #8004 on: August 09, 2022, 10:32:22 PM »
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Where do we get that Cooper was even wearing a parachute when Tina last saw him? Is that from Tosaw's interview or something? Unless I'm mistaken and I've read them many times recently, neither of her FBI interviews mention her seeing him actually wearing a chute. Just trying to figure out if the last time she saw him whether or not he had put on his chute yet. We all seem to assume that I'm struggling to actually find that.

Tina gave a statement to the FBI that she saw Cooper put on one of the backpack parachutes like he knew what he was doing.  This was while the airliner was still on the ground at SEATAC.  Tina's comments were documented very early in the investigation.

When Cooper told Tina that she could go to the cockpit, just a few minutes after the takeoff from SEATAC, he also told her to close the curtain between the first class and rear portion of the cabin.  As Tina was closing that curtain, she had her last look at Cooper and stated that he was tieing some of the shroud lines from the reserve pack that was left on the aircraft around his waist.  This can only mean that Cooper still had on the parachute and that it was over his raincoat.


Yes, I'm referring to her two interviews in the 302's. I've read them many, many times. She appears to mention nothing about him actually wearing a parachute in those two FBI interviews. She says he was "completely familiar with the parachutes he was given."

I'm also not going to assume that he's wearing his parachute when he's tying this crap to himself. She says in the interview that "the last time she saw him he had a nylon cord tied around his waist and was standing in the aisle."

Am I missing something in one of her FBI interviews where she says that she saw Cooper put on the parachute? If someone could point out to me where she says that I'd appreciate it.

My assumption would be that if he's still tying things around his waist the last time she sees him then perhaps he wasn't wearing his chute at that point. Wouldn't it be a little cumbersome to be wrapping things around your waist while wearing a bulky NB-8? I mean...I think I'd like my parachute pack to have an unencumbered opening.

The "complete familiarity" she's referring to might have been with how he knew where everything was on the parachutes when he was cannibalizing them and his dismissal of the instructions, etc.

I've just been reading her interviews a bunch lately and I was struck by the fact that she never seems to mention him actually putting on his chute unless I've missed it somehow.

I suggest that you go to "DropZone.com, forums, skydiving history & trivia, db cooper" and join that thread.  It only takes a few seconds.

FlyJack's post #57532 on that thread discusses the above subjects.  I don't have time to search the FBI files but here are a couple of references to the above.

Richard Tosaw's book, page 32, discusses Tina watching Cooper put on the backpack parachute.  Page 34 discusses the last time she saw Cooper as she closed the curtain.

Ralph Himmelsbach's book, page 42, discusses the last time Tina saw Cooper as she closed the curtain.
 

Offline Robert99

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Re: Clues, Documents And Evidence About The Case
« Reply #8005 on: August 09, 2022, 10:33:33 PM »
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Under the conditions that existed on November 24, 1971, Rataczak, Scott, and Anderson would be able to see the glow from the lights in the Portland/Vancouver area from some distance away.  The visibility on the ground at Portland International Airport was reported as about 10+ miles (it was not exactly measured and was probably greater) and the visibility between cloud layers was probably about the same.

I lived in the Phoenix area for quite a few years and the visibility at Sky Harbor Airport was typically given as 10 miles.  But on those days with 10 miles of visibility, I could typically see 40, 50, or 60 miles while driving down the freeway.
Interesting. That certainly would give them a general area, but hardly anything specific.

What do you mean by that?
If they saw the glow of lights of Portland from a distance - say a standard 10 miles - they would have a general idea of their location, but would not be able to pinpoint on a map their exact location from the lights alone.

Correct.
 

Offline Robert99

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Re: Clues, Documents And Evidence About The Case
« Reply #8006 on: August 09, 2022, 10:38:17 PM »
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Under the conditions that existed on November 24, 1971, Rataczak, Scott, and Anderson would be able to see the glow from the lights in the Portland/Vancouver area from some distance away.  The visibility on the ground at Portland International Airport was reported as about 10+ miles (it was not exactly measured and was probably greater) and the visibility between cloud layers was probably about the same.

I lived in the Phoenix area for quite a few years and the visibility at Sky Harbor Airport was typically given as 10 miles.  But on those days with 10 miles of visibility, I could typically see 40, 50, or 60 miles while driving down the freeway.
Interesting. That certainly would give them a general area, but hardly anything specific.

What do you mean by that?
If they saw the glow of lights of Portland from a distance - say a standard 10 miles - they would have a general idea of their location, but would not be able to pinpoint on a map their exact location from the lights alone.

To determine their location all the flight crew had to do was look at their instruments.  They had two VORTAC receivers, two DME receivers, and two ADF receivers and were supposedly tracking down V-23.  The VORTAC receivers would give them their lateral position to within less than a mile and the DME receivers would give them their longitudinal position to well less than a mile.  Their onboard navigation information was more accurate than any radar information.
That's not what Rataczak told Bruce Smith in his book:

"Flight 305 didn't have the capacity to determine its exact location. Only the air traffic controllers could determine our position."

The airliner DID have the ability to determine its exact location!  But if they were relying on ATC to do their navigation they were not tracking the centerline of V-23 or anything close to it.  This supports the Western Flight Path since ATC would be giving them headings to fly.
 

Offline Robert99

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Re: Clues, Documents And Evidence About The Case
« Reply #8007 on: August 09, 2022, 10:59:18 PM »
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Persistent pesky questions about them stairs and the oscillations and bump...

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...going down a couple of steps past that hinge point is going to lower the stairs enough to create pressure changes in the cabin that would be noticeable in the cockpit cabin altitude instrument...     ...this time, he goes way down the steps as far as he can, perhaps to the very end of the stairs, and jumps.  Cooper's weight on the stairs will not lower them to the same degree as they are lowered on the ground.  But when Cooper steps off those stairs they slam up into their closed position but don't lock there...     

In that clip from the Treat Williams movie, when the stunt guy jumps off the stairs, they retract very slightly and slowly. They certainly don't 'slam' shut, even momentarily. I would imagine the pilot could feel a bit of change on the pitch influence, but I don't see it re-sealing the cabin momentarily and causing a pressure event. For the stairs to behave in the way described, I would guess that Cooper would have to have pulled the emergency release, which should disconnect them from the hydraulic system and allow them to free-float. But I'm told that did not happen, that he did not pull the emergency release. So would there be that much variable from plane to plane, how much the stair door would be able to move while still connected to (dampened by) the hydraulic system?  ...??
I don't have a good answer for that either. I have heard different things - the stairs hydraulics were not deployed and the stairs were freefloating and vice versa. Regardless, it seems that the pressure bump was simulated during the drop test in January 1972.

Here is what I do know:  the cabin rate of climb and descent gauge uses a sensor in the cabin to measure cabin pressure altitude. During an unpressurized flight - like the Cooper hijacking for example - it will read approximately the altitude that the aircraft is at. It will respond just like the flight altimeter - going up and down with the aircraft.

I propose that the 727 was experiencing what's known as a phugoid.

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If the plane was experiencing a phugoid, that would be reflected as oscillations in the cabin rate of climb indicator. I think the slow extension of the airstairs by Cooper caused phugoid oscillations in the aircraft that the crew noticed on the gauges. When Cooper jumped, the crew experienced a pressure bump - a rather well-known phenomenon in aviation when the pressure of the cabin increases dramatically - that usually causes your ears to "pop". When that happened, the airstairs were no longer descending and the aircraft stabilized from its phugoid.

Thus, while both phenomena - the phugoid oscillations and the pressure bump - were caused by Cooper's behavior on the airstairs, they were distinct things. Whether the crew, the airline flight ops, or the FBI understood the difference when it happened or immediately after is the question.

Chaucer, as an aeronautical engineer my main time was in flight dynamics which included aircraft performance and stability and control.  Longitudinal aircraft stability involves a short period mode and a longer mode called the phugoid.

The short period mode is typically completely damped out within a couple of seconds and is not generally noticeable to the pilot.  I have never noticed anything that I could identify as the short period mode in flying powered general aviation aircraft and unpowered sailplanes.

I have more than 1000 hours of flying time in unpowered sailplanes which spend about 90 percent or more of their time in maneuvering flight.  Consequently, for sailplanes, it is desired that the longitudinal stability be essentially zero.  This means that when the pilot takes his hand off the stick the sailplane will diverge longitudinal as well as about the other two axes.  Longitudinally, this divergence is the phugoid and it will never dampen itself out.  Without corrections by the pilot the sailplane will end up in a spiral and if it stalls it will spin.  Long flights in sailplanes can be very tiring.  My longest flight sailplane flight was about 7 hours and 20 minutes.  After landing, it took me at least 5 minutes to get out of the cockpit and stand up and I felt lousy the next day.

Powered aircraft, even fighter aircraft, generally spend about 90 percent or more of their time in straight and level flight.  Again, the short period mode dampens out in only a few seconds.  But the phugoid mode may take 4, 5, 6, or more minutes, repeat minutes, to dampen out naturally if it ever does so.  Hand flying early jet airliners at high altitudes was particularly tiring for the pilots due to the phugoid.  Consequently, the autopilots were typically activated as soon as possible after takeoff and stayed on until the descent for landing.
Flying a sailplane sounds like fun. Too bad I'm a nervous flyer. Go figure.

Quote
But the phugoid simply cannot explain the cabin pressure altitude oscillations or the bump when the stairs hit the fuselage when Cooper jumped.  It is just not possible.
First, in my post I said that the phugoid would explain the cabin pressure oscillations, but NOT the bump. The bump, I think as has been clearly shown, is caused by the door swinging back up after Cooper jumped.

Second, since this would appear to be your area of expertise, I would hope you could explain why a phugoid mode can't explain the oscillations in the cabin pressure rate of climb. I may be wrong about it, and I only offered it up as a possibility. At its face, it appears to make sense. Rather than simply tell me it's not possible, tell me why.

Simple.  The autopilot or the pilot hand flying the aircraft would cancel out the phugoid and it would not be a factor in the cabin pressure oscillations.

This is not an insult.
I certainly think if the autopilot was on, then a phugoid would be easily dampened. I don't think the autopilot was on.

With that said, would flying unpressurized at night through clouds with little frame of reference, impact the ability of the pilot to detect a phugoid and thereby react to it? Rataczak obviously had a lot of other things to be distracted about.

I'm not arguing strongly in favor of a phugoid. I'm sincerely asking. If it's not possible, then it's not possible.

It's not possible.  Again, the phugoid was never a factor.

Flying at night through clouds and unpressurized doesn't mean anything.  The gyroscopic instruments on their instrument panel was all they needed for reference.

In 1971, in addition to an FAA Pilot's Certificate, I also held an FAA Ground Instructor Certificate that permitted me to teach pilots Basic, Advanced, and Instrument Flying.  While I never had a pilot's certificate for instrument flying, I have quite a few hours of flying under a hood with a safety pilot on board and this included ILS and other instrument approaches.  Some of that flying was done in two-place sailplanes with the only gyroscopic instrument being a "needle and ball" which predates today's "turn coordinators".

The above is not an insult.     
 

Offline Olemisscub

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Re: Clues, Documents And Evidence About The Case
« Reply #8008 on: August 09, 2022, 11:10:13 PM »
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I suggest that you go to "DropZone.com, forums, skydiving history & trivia, db cooper" and join that thread.  It only takes a few seconds.

FlyJack's post #57532 on that thread discusses the above subjects.  I don't have time to search the FBI files but here are a couple of references to the above.


Thanks. Fascinating that parallel queries about Tina seeing him putting on his chutes were occurring simultaneously on both boards. haha.

That wasn't in the searchable 302 database that I've been using. I knew we had something evidentiary showing that Cooper had his chute on, but I was starting to second guess it when I couldn't find it in the 302's.

That does beg the question...did he take the chute off for a bit when he was tying the cord around his waist? How exactly would you tie something around your waist wearing a bulky old NB-8? Am I overthinking it? I've never worn a parachute for what it's worth. Although I see an NB-8 on ebay for $200 and I'm considering buying it just for the hell of it.
 

Offline Robert99

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Re: Clues, Documents And Evidence About The Case
« Reply #8009 on: August 09, 2022, 11:36:59 PM »
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I suggest that you go to "DropZone.com, forums, skydiving history & trivia, db cooper" and join that thread.  It only takes a few seconds.

FlyJack's post #57532 on that thread discusses the above subjects.  I don't have time to search the FBI files but here are a couple of references to the above.


Thanks. Fascinating that parallel queries about Tina seeing him putting on his chutes were occurring simultaneously on both boards. haha.

That wasn't in the searchable 302 database that I've been using. I knew we had something evidentiary showing that Cooper had his chute on, but I was starting to second guess it when I couldn't find it in the 302's.

That does beg the question...did he take the chute off for a bit when he was tying the cord around his waist? How exactly would you tie something around your waist wearing a bulky old NB-8? Am I overthinking it? I've never worn a parachute for what it's worth. Although I see an NB-8 on ebay for $200 and I'm considering buying it just for the hell of it.

First, don't buy the NB-8 parachute.  Neither an NB-8 nor NB-6 parachute was involved in the hijacking.  Further, don't believe anything Cossey said even with corroboration.  His only connection with the Cooper parachutes was that he packed all of them.

Hayden provided the two backpack parachutes that were given to Cooper and he said they were identical.  The surviving backpack is now on display at the WSHM in Tacoma, WA.  The pictures of that backpack indicate that it was put together from a collection of parts that came from different designs and did not itself have a formal designation.

Cooper probably kept the parachute on once he initially did so.  He could easily run the shroud lines tied to the money bag between the harness and container.  Actually, he should have tied the money bag lines to the harness rather than to his body.