Anyone want to speculate on how many "dry runs" DBC did prior to the curtain going up?
Many here would likely guess at zero, as they take everything Cooper said or did at face value only. They seemingly think he was some sort of simpleton who got astronomically lucky in getting away with it. Any time it is suggested that this was well-planned from beginning to end, gets nearly ridiculed here... and to those who are still reading...if the shoe fits...
Since the above is apparently addressed to me, let me reply at some length. What purpose would a dry run serve?
Cooper knew from the outset that he would be making a night jump and he knew that the weather was bad when he bought the ticket in Portland. He knew that it was raining in Portland since he was wearing a rain coat and just looking up would have given him a realistic view of the clouds.
He could also see the clouds as the airliner climbed up through them on the way to Seattle, but he had actually hijacked the airliner before it even got off the ground.
There is no way that Cooper could have known his location, even approximately, after the airliner took off from Seattle and climbed above the clouds into the night sky. So when Cooper did jump, he had no way of determining what was below him until he was below the lowest cloud level in a pitch black night.
Cooper can thank NWA personnel for saving his bacon up to the point where he jumped. J. Edgar Hoover did not like to be shown up by some two-bit hijacker and probably would have told his agents in Seattle to storm the plane and kill the hijacker if NWA had not intervened. Some members of this thread have had their closest relatives killed as "collateral damage" in shoot outs between FBI agents and would be aircraft hijackers.
The fact that Cooper did not specifically ask for sky-diver parachute rigs, with back and chest parachutes, indicates a lack of planning and/or knowledge. He was aware of some of the performance data for the 727 and that indicates he had some training or experience with that specific aircraft.
Cooper did know that the 727 aft stairs could be lowered in flight and that the 727 could take off with the stairs unlocked. Nevertheless, Cooper did not know how to lower those stairs himself. This suggests to me that Cooper's 727 experience was on the modified 727s that Boeing prepared for Southeast Asia operations. And I have stated several times over the years, Cooper was probably a former military or CIA type who had worked either directly for the USA Government or one of its contractors.
But again, I see nothing that would require a dry run.