On the afternoon of 24 November 1971, a quiet man in a business suit walked up to the Northwest Orient counter in Portland, Oregon, and paid cash for a one-way ticket to Seattle. He gave his name as Dan Cooper. A few hours later he would step out of the back of a Boeing 727 into a freezing night sky with $200,000 strapped to his body — and vanish so completely that, half a century on, no one knows who he was or whether he lived.

It is the only unsolved commercial hijacking in American history, and the most tantalising mystery in the story of flight.

A bomb, a note, and a drink

Cooper looked utterly ordinary — mid-forties, dark suit, black tie, white shirt. He ordered a bourbon and soda as the aircraft waited to take off. Then, shortly after three o’clock, he handed a note to flight attendant Florence Schaffner. When she slipped it into her pocket unread, he leaned over and told her quietly to look at it.

He opened a cheap attaché case just far enough to show her a tangle of wires and red-coloured sticks, and dictated his demands: four parachutes and two hundred thousand dollars in twenty-dollar bills. When the 727 landed in Seattle, he calmly traded the 36 passengers for the money and the chutes, kept a few crew members aboard, and ordered the aircraft back into the air, bound for Mexico City — low and slow.

The FBI’s account of the hijacking and manhunt.

Into the night

Somewhere over the dark forests of southwest Washington, a little after eight in the evening, Cooper did the almost unthinkable. He lowered the aft airstair of the moving jet, and with two of the four parachutes and the bag of cash, he jumped.

The 727 landed safely at Reno at 10:15 p.m. Cooper, the money, and two parachutes were gone. The FBI opened a sprawling investigation it codenamed NORJAK, interviewed hundreds of people and, within five years, had weighed more than 800 suspects. None could be proven to be Cooper.

The clue in the river

For nine years, there was nothing. Then in 1980 a young boy digging on a sandy bank of the Columbia River unearthed a rotting package of twenty-dollar bills — $5,800 in all — and the serial numbers matched the ransom exactly. It was the only physical trace of the money ever found, and it deepened the mystery rather than solving it. How did it get there? Did Cooper survive at all?

The FBI formally closed its active investigation in 2016, no closer to a name than it had been in 1971. Cooper did leave one legacy in the sky: after his escape, the Boeing 727 fleet was fitted with a device — the “Cooper vane” — that makes it impossible to lower the rear airstair in flight, so no one could ever repeat his trick. The man himself simply stepped into the dark and became a legend. Somewhere out there, the rest of the money may still be waiting.

The only hijacking America never solved.

The enduring mystery of D.B. Cooper.

Sources: Federal Bureau of Investigation; Britannica; History.com.