The D.B. Cooper hijacking had specific and lasting consequences for the design of commercial aircraft and the security practices of American aviation.
The most direct equipment change was the “Cooper vane”—a small mechanical modification to the aft airstair of Boeing 727 aircraft. The vane was a device installed at the base of the airstair that made it impossible to lower the stairway while the aircraft was in flight and the engines were running. The modification was mandated by the FAA after the hijacking. Once the Cooper vane was installed across the 727 fleet, the specific method Cooper used—deploying the aft stair in flight and jumping from it—became physically impossible on those aircraft.
The broader security changes of the early 1970s were not caused solely by Cooper’s hijacking; they were driven by a wave of hijackings across the decade, some of which were far more violent. But Cooper’s case contributed to the regulatory environment that established new screening requirements for commercial aviation.
Court rulings in the years immediately following 1971 established the legal framework for what airports could require of passengers. The use of a hijacker profile to select passengers for screening was upheld by a federal court in 1971. The use of magnetometers—metal detectors—was upheld in 1972. The authority to search passengers for weapons was upheld in 1973. These rulings built on each other and helped create the screening environment that, while transformed many times since by subsequent events, had its legal foundation laid in the early years of the 1970s.