The Harrier, informally referred to as the Harrier Jump Jet, is a family of military jet aircraft capable of vertical/short takeoff and landing (V/STOL) operations.he BAE Systems/Boeing Harrier II is a modified version of the AV-8B Harrier II that was used by the Royal Air Force (RAF) and the Royal Navy until 2010. Between 1969 and 2003, 824 Harrier variants were delivered.