Ralph Himmelsbach, the FBI agent assigned to the case before his retirement in 1980, has long maintained Cooper was a bumbler and a fool.
If the cold didn't kill him, if he withstood the powerful turbulence, Cooper was still parachuting into dense forest at night, at the onset of winter, with no food or survival gear.
"It was a bad place to land, and it is doubtful we would ever find the body,"
If this is true, then who buried this money?:
$5,880 of his loot was found by a boy playing on the banks of the Columbia River in 1980.
start with an airborne qualified individual, recently retired from the armed forces.
Spends time on recon of the actual takeoff time, and how long it takes to get over a specific place.
Might even take a few practice flights to scan the area during daylight hours.
Asks the flight attendant to get in front, then grabs a case from the overhead, changes into boots, cold weather gear and other survival gear, perhaps some food, grabs an extra chute, like a good trooper, and bails out into history. Plausible??
PS: May even have had transportation arranged or stashed?