In the history of the U.S there is only one unsolved airline hijacking case

There is only one unsolved airline hijacking case in the history of the U.S. The hijacker parachuted out of the plane after receiving his demands, and was described as “thoughtful and polite” by his hostage.

D. B. Cooper is a media epithet popularly used to refer to an unidentified man who hijacked a Boeing 727 aircraft in the airspace between Portland, Oregon, and Seattle, Washington, on November 24, 1971, extorted $200,000 in ransom (equivalent to $1,160,000 in 2014), and parachuted to an uncertain fate. Despite an extensive manhunt and an ongoing FBI investigation, the perpetrator has never been located or positively identified. The case remains the only unsolved air piracy in American aviation history.

The suspect purchased his airline ticket using the alias Dan Cooper, but due to a news media miscommunication he became known in popular lore as “D. B. Cooper”. Hundreds of leads have been pursued in the ensuing years, but no conclusive evidence has ever surfaced regarding Cooper’s true identity or whereabouts. Numerous theories of widely varying plausibility have been proposed by experts, reporters, and amateur enthusiasts. The discovery of a small cache of ransom bills in 1980 triggered renewed interest but ultimately only deepened the mystery, and the great majority of the ransom remains unrecovered.

While FBI investigators have insisted from the beginning that Cooper probably did not survive his risky jump, the agency maintains an active case file—which has grown to more than 60 volumes—and continues to solicit creative ideas and new leads from the public. “Maybe a hydrologist can use the latest technology to trace the $5,800 in ransom money found in 1980 to where Cooper landed upstream,” suggested Special Agent Larry Carr, leader of the investigation team since 2006. “Or maybe someone just remembers that odd uncle.”

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