General Category > DB Cooper

General Questions About The Case

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snowmman:
I read an extended description of Al Tyre's reconnect with Ted in the famous truckstop breakfast in 1973

I hadn't noticed this before
"During the encounter in the service area in 1973, Tyre and Ted had breakfast together. Ted also asked him if he had followed the DB Cooper hijacking case. Tyre said he hadn't."

wonder if that's true.

snowmman:
robert edwards commentary on the details of the boeing air stairs tests is reasonable, and here:
with discussion about hydraulics

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also a later update
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this second post has images showing oscillations in airplane altitude. I think he made the graphs from the data in the fbi files?

Edwards makes an interesting point:
"If on Flight 305 the autopilot was engaged (as the FBI assures us was the case) and "altitude hold" was switched on (which I think probable), it would compensate for the pitch-up without any intervention by the pilot, and would return the airplane to the desired angle of attack and to the desired altitude. There would surely have been some oscillations in the airplane's altitude, in the cabin's equivalent altitude, and in the cabin rate-of-climb (rate of change of cabin pressure), as there were in Boeing Test 100-1, summarized in the graphs below.]"

also:
"[I believe that there were at least three relevant differences between the Boeing tests and Flight 305.
* In the Boeing tests, the landing gear was up. On Flight 305, the gear was down.
* In the Boeing tests, according to my correspondent, the autopilot was probably disengaged. On Flight 305, according to two statements to the FBI by Northwest's Director of Flight Operations (Technical), the autopilot was engaged throughout most of the segment between Seattle and Reno. A former senior FBI agent advised me that the FBI had no reason to question these statements.
* In Boeing Test 100-1, all the interior panels in the stairwell were removed. to avoid possible damage. I do not know what the aerodynamic effects might have been, but I suspect that this condition would have created more turbulence in the stairwell. In Boeing Test 100-3, the panels were re-installed. On Flight 305, all the panels were in place."



He has a nice pic of N727000 doing a test drop over the Pacific with the stairs removed. Interestingly, the payload and parachute descend at a more vertical angle from the plane, then I've seen in other test drops. (in other tests)

interestingly Edwards said
"Back on March 5, 2020, I had submitted a FOIA request for all reports relating to the Boeing test flights. The FBI replied on July 6, 2020, to the effect that they had searched for the reports and found nothing."


and then the FBI released the files with the detailed test reports.
Weird.

snowmman:
good thoughts by Edwards on the oscillations
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Edwards: (this is 8/16/22 so Edwards is musing post-book, and with new knowledge from newly released fbi files)

As mentioned in earlier posts, I discussed Boeing report D6-7771, on the Boeing tests 100-1 and 100-3 of the 727-22 in 1964, with an aerospace engineer who knows the Boeing 727 well.

He advised that on the Boeing tests, given the frequent references to manual trim, the autopilot was probably not engaged. However, with regard to Flight 305 between Seattle and Reno, I had reached the conclusion that the autopilot was almost certainly engaged most of the time.

This represented a significant difference between the configuration of the Boeing tests and that of Flight 305. With the autopilot engaged, any excursions in the control axes would be quickly corrected. Consequently, I would have expected any oscillations on Flight 305 to be much smaller than those on the Boeing tests.

I therefore asked my correspondent:
"... on Flight 305, given that the autopilot was engaged and that (probably) "altitude hold" was on, is there a way to estimate the maximum altitude excursions from 10,000 feet AMSL resulting from deployment of the airstair? I'm wondering: plus or minus 100 feet? More, or less?"
His reply was as follows [with my comments in square brackets]:
"... I would expect that [on Flight 305] the altitude fluctuation due to airstair deployment was less than 100 feet, especially with the autopilot engaged. The pilots would have needed to add some power to maintain airspeed. I am inclined to say that any altitude deviations of significance, if they existed, were more likely due to the weather of the evening [of November 24, 1971] than to the airstair deployment."
We recall that the crew's report of the oscillations on Flight 305 led to an estimate of the place and time of the hijacker's leap, which led to the delineation of a search area, where the FBI found nothing. We may wonder whether the oscillations on Flight 305 led the FBI down a wrong track, from which they were unable to return.

377:
Are you sure the 727 autopilot maintained AOA? I see only altitude hold in a casual look through my manuals. It would respond to the lowered stair but only by sensing a change in baro altitude and pitching up to maintain the set value. I may be incorrect. I have not looked at it in depth yet.

377

377:
Braden is still a fascinating DBC candidate.

When I spoke with MAC SOG MSgt Billy Waugh, he was quite certain Ted Braden was DB Cooper.
He said that most of his colleagues agreed.

Snowmman is in the building.

377

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