The hijacking crisis crew on the ground, including Seattle cops, FBI agents, Northwest employees and Federal Aviation Administration officials, had roughly 30 minutes to meet Cooper's demands. The FBI scrambled to assemble the $200,000 cash while
Cooper had specified $20 bills—an indication of his attention to detail in the planning. He apparently had calculated that 10,000 $20 bills would weigh just 21 pounds. Smaller denominations would add weight and danger to his skydive. Larger denominations would be more conspicuous and therefore more difficult to pass.
Cooper specified the bills should have random, not sequential, serial numbers. FBI agents followed his instructions but made sure each bill began with the code letter L, issued by the Federal Reserve office in
Meanwhile, the search for suitable parachutes was more difficult than acquiring $200,000 cash.
The task at first seemed simple. Authorities at
Cooper's hijacking note did not spell out his plan to skydive with the loot, but the authorities were able to deduce his intentions. They puzzled over his request for two sets of chutes. Did he plan to take along a passenger or crew member as an airborne hostage? The question negated any thoughts of using dummy parachutes that would end the hijacking—and the hijacker's life—with a splat. To some, it was another brilliant detail of his plan.
Aboard the jet, Cooper drank a bourbon and water—and, oddly, offered to pay Mucklow for the highball. Cooper's manners and temperament have been the subject of some disagreement. By the FBI's account, he was boozy and rather raunchy. Ralph Himmelsbach, a lead FBI investigator on the case, has said the hijacker used "filthy language" and was "obscene."
Yet Mucklow, who spent more time with Cooper than any other crew member, has described him as a gentleman. She said, "He seemed rather nice. He was never cruel or nasty. He was thoughtful and calm." One example was Cooper's request that meals for the crew be brought on board once the jet was on the ground in
Investigators surmised that Cooper was native to the
He was well-acquainted with skydiving and schooled in jet aerodynamics, including such details as the specs for wing flap angles and minimum air speeds for the Boeing 727. Some believe he was an active or retired airman who had spent time stationed at McChord.



