I'm at page 10 of the transcripts and I find one interesting new thing.
(abbreviations are easy to decipher. These apparently were typed on the fly. .typist apparently used "



"
at the end of a word if he made an error..no backspace in those days! so ignore words ending in



in the transcripts)
Cooper specified they would fly with the "AFT STAIRS TO BE LWRD AFTER TKOFF"
and "AFT PSGR LOADING DOOR WILL BE OPEN" even before they took off after fueling
see page 10.
"305 R HAVEXXX AFT PSGR LOADING DOOR WILL BE OPEN AND WILL REMAIN IN THAT POSN AND AFT STAIRS TO BE LWRD AFTR TKOFF"
The pilot/control apparently thought the stairs couldn't be lowered in flight, so there was all sorts of debate about taking off with the stairs down or partially down. But Cooper didn't say that. He was comfortable with the idea of opening in flight. What's weird is that they later say they had dumped two to three hundred lb. boxes out the aft stairs...so they must have known they could be opened in flight (since you can't take off that way)..so they weren't thinking straight. They just didn't know. Maybe there's a lot of exchanges with experts not shown, gathering this kind of info on the fly..so we see some communication early on where they didn't know about 727 experience with aft door/stairs open while flying.
on page 10/11 (note the



's are I think the guy on the typewriter trying to correct mistakes...so ignore those)
"305 HAV NOXXX NEGOTD RLS OF 2 GIRLS LVG ANY MOMENT 3RD GIRL TO STAY ITH ACFT WANTS HER TO MANIPULATE STAIRS FOR HIM AFTR PLANE AIRBORNE HAVE TRIED TO TELL HIM INXXX UNAM OPRTE STAIRS TO LWRD AFTR TKOFF TRYING TO GET HIM TO LET US LWR STAIRS PARTLLY FOR TKOFF"
"MSP FLT OPNS DONT KNOW OF ANY WAY TO LOCK STAIRS IN INTMTDE POSN"
"305 R WIL TALK TO HIM AGAIN"
So it's not like there was some surprise when he lowered the aft stairs.
The previous reports made it out to be a big surprise when he lowered the stairs in flight. They knew he wanted to do that all along. The combination of stairs, plus flaps (and gear down?) is what led them to say they wouldn't make Mexico.
Cooper hadn't thought of that...the issue of more fuel needed if he tells them Mexico with flaps and stairs. He wasn't really going to Mexico, so he kinda missed that issue in his tunnel thinking.
Here's another important note.
at 5:47 PM PST
"305 WE HAVE INSTRCTNS FROM THE INDVDL WANTS NR1 (?) GO TO MEXICO CITY 2 TO FLY WITH GEAR DOWN AND FLAPS AT 15 EGDEG AFTR UNDERWAY ALL LITHGHTS TO BE TURND OUT IN ACFT"
So it's not clear that Cooper specified 15 degree flaps. The pilot reported 15 degree flaps. It's possible Cooper just told the pilot to lower the flaps, and the pilot was just being precise in reporting to the tower the exact state and why that wouldn't let him fly to Mexico.
This is important because a lot of reports quote the flap degree specification as evidence of Cooper being an aviation person. There's nothing that says Cooper specified the degree of the flaps. (on second thought, I'm thinking Cooper did specify 15. It's consistent with how the pilot relays demands from Cooper)
It's possible Scott later said Cooper requested 15 degrees. But it's also possible that he didn't. (I'm thinking in the end Cooper did say 15 ..see bottom here. But did he calculate 15 degrees as a Boeing engineer experienced in trim/stabilizer calcs, or did he have firsthand experience in a flight that opened the aft doors (vietnam/cia or ??))
page 11 and 12 has notes about how they can't take off with the stairs down...so Cooper wasn't that expert...he didn't know a lot about the aft stairs...It was going to be news to him that they'd have to lower in flight.
note on page 12 they say they know the plane has been flown with the stairs lowered
"MSP FLT OPS HAVE NO CNTRL PROBLEM WHEN XTNDD MAY BE SUM SLITE PITCHUP BUT ERY CNTRLLBL PLANE HAS BEEN FLOWN THIS WAY HAVE LARGE BOXES OF 2 TO 3HND LBS THRU THE DOOR IN THIS CONFIG MUST BE DOWN WITH LANDING FLAPS SPEED NOT TO CRITICAL ANY FLAT POSN BTWN 5 AND 40 AND SPEED TO 120 KTS DONT HAVE ANGLE YET BUT WORKING ON IT"
I wonder if the experience shoving two to three hundred pound boxes thru the open aft door, was from Vietnam?
So the tower was trying to work out what kind of trim was needed with the flaps, to keep the plane from pitching up, while flying with the aft stairs down...
But: Maybe he is insisting on a flap degree:
on page 12
"305 HE SEEMS TO BE INSISTENT WITH STAIRS IN 1 DEG" (typo? maybe 15?)
"MSP IMPOSS TO TKOFF WITH STAIRS XTNDD BUT FULL UTXXX UP"
"305 R WANTS GIRL TO INITIATE STAIRS AFTR TKOFF SHUD WE TIE HER DOWN TO STRUCTURE"
I think maybe Cooper understood the trim issues of a plane. If he was a laid-off Boeing engineer like I think, maybe he calculated the required flap angle with aft stairs lowered, to keep the plane trim.
on page 13/14 they note at 7:34 PM
that he's trying to lower the stairs and they have an aft stair lite on
they say they're 14 miles on V23 (vector 23)
So the aft stairs were lowered a lot earlier than 8:05?
page 16 is where they Stewardess Mucklow sees him with the "KNAPSACK AROUND HIM AND THINKS HE WILL ATTEMPT A JUMP"
they say indicated speed is 160 knots on page 16? and they're at ten thousand feet or are they at 15 thousand "indicated" as he says, and they're going to 10 thousand...Not clear when they got to 10 thousand. Note the gear is down in addition to the flaps.
So is the plane going slower than previously indicated? And Cooper maybe jumped before they got to 10 thousand? not clear. If he jumped between 8:05 and 8:12 I guess they had time to come down to 10 thousand.
"MSP FLT OPS WHT IS ALTDE"
"305 NOW AT 15THSD INDCTD 160 FUEL FLOW 4000 15 DEG FLAP GEAR DOWN CQN WILL STAY AT 1XX TEN THSD TIL HAS LEFT"
"8:01 PM PST"
(the time for an exchange is always last in the group)
at 8:12 PM on page 18, the pilot notes the oscillations and says he
must be doing something with the "AIR STAIRS"
at 8:05 PM on page 17 they noted trying to make contact with Cooper two times but no response. But then he did respond on the PA system.. so he's still there at 8:05 PM..
So there's a big 7 minute window of time where they don't really know where he jumped. The oscillation could have been from the stairs going full lowered when weighted by Cooper (as FBI testing showed) or maybe not
He could have jumped/fell after the oscillation..i.e. the FBI test had a guy walk out on the stairs, not actually jump (they used a sled for another test...)...maybe cooper hung on the stairs for a little while when he felt the plane oscillation..Maybe he jumped/fell 1 minute or so after the oscillation...i.e. around 8:13
still reading (I'm on page 18 of 99)
The new info for me was that the aft stairs were lowered well below 8:05...i.e. 7:34
So Cooper was waiting...waiting until he saw his (or maybe a?) desired landing zone before jumped.
He didn't just get the stairs open and go for it right away.
Combine that with being able to see Portland/Vancouver lights thru the cloud cover, and it makes me more comfortable about Vancouver being the targeted jump zone.