A Cooper vane (also sometimes called a Dan Cooper switch or D.B. Cooper device) is a mechanical

aerodynamic Aerodynamics, from grc, ἀήρ ''aero'' (air) + grc, δυναμική (dynamics), is the study of the motion of air, particularly when affected by a solid object, such as an airplane wing. It involves topics covered in the field of fluid dyn ...

wedge that prevents the ventral

airstair An airstair is a set of steps built into an aircraft so that passengers may board and alight the aircraft. The stairs are often built into a clamshell-style door on the aircraft. Airstairs eliminate the need for passengers to use a mobile st ...

of an aircraft from being lowered in flight.

History

In the United States, following three hijackings in 1972, the

Federal Aviation Administration The Federal Aviation Administration (FAA) is the largest transportation agency of the U.S. government and regulates all aspects of civil aviation in the country as well as over surrounding international waters. Its powers include air traffic ...

ordered that

Boeing 727 The Boeing 727 is an American narrow-body airliner that was developed and produced by Boeing Commercial Airplanes. After the heavy 707 quad-jet was introduced in 1958, Boeing addressed the demand for shorter flight lengths from smaller air ...

aircraft be fitted with Cooper vanes. The device was named for an unidentified airplane hijacker dubbed

D. B. Cooper D. B. Cooper is a media epithet for an unidentified man who hijacked Northwest Orient Airlines Flight 305, a Boeing 727 aircraft operated by Northwest Orient Airlines, in United States airspace on November 24, 1971. During the flight from Portl ...

, who used the rear stairway to exit a Boeing 727 in flight and make a

parachute A parachute is a device used to slow the motion of an object through an atmosphere by creating drag or, in a ram-air parachute, aerodynamic lift. A major application is to support people, for recreation or as a safety device for aviators, w ...

escape.

Design

The Cooper vane is a very simple device: It consists of a spring-loaded paddle connected to a plate that prevents the ventral

of an aircraft from being lowered in flight. When the aircraft is on the

ramp An inclined plane, also known as a ramp, is a flat supporting surface tilted at an angle from the vertical direction, with one end higher than the other, used as an aid for raising or lowering a load. The inclined plane is one of the six clas ...

, the spring keeps the paddle perpendicular to the

fuselage The fuselage (; from the French ''fuselé'' "spindle-shaped") is an aircraft's main body section. It holds crew, passengers, or cargo. In single-engine aircraft, it will usually contain an engine as well, although in some amphibious aircraft t ...

, and the attached plate does not block the stairway. As the aircraft takes off, the airflow pushes the paddle parallel to the fuselage and the plate is moved underneath the stairway, preventing it from being lowered. Once the airflow decreases on landing, the spring-loaded paddle returns to its initial position, thereby allowing the stairs to be lowered again.

McDonnell Douglas DC-9 The McDonnell Douglas DC-9 is an American five-abreast single-aisle aircraft designed by the Douglas Aircraft Company. It was initially produced by the developer company as the Douglas DC-9 until August 1967 and then by McDonnell Douglas. Afte ...

aircraft with ventral stairs were also equipped with Cooper vanes.

References

{{reflist, 25em, refs= {{cite magazine , last=Gladwell , first=Malcolm , date=October 2001 , title=Safety in the skies: How far can airline security go? , magazine=

The New Yorker ''The New Yorker'' is an American weekly magazine featuring journalism, commentary, criticism, essays, fiction, satire, cartoons, and poetry. Founded as a weekly in 1925, the magazine is published 47 times annually, with five of these issues ...

, page=50 , url=http://gladwell.com/safety-in-the-skies/ , url-status=dead , archiveurl=https://web.archive.org/web/20141218130651/http://gladwell.com/safety-in-the-skies/ , archive-date=18 December 2014 {{cite book , last=Schneier , first=Bruce , year=2003 , title=Beyond Fear: Thinking sensibly about security in an uncertain world , publisher=Springer Science & Business Media , isbn=0-387-02620-7 , pag
82
, url=https://archive.org/details/beyondfearthinki00schn_0 , url-access=registration Aircraft doors Locks (security device)