Officially called the Fighting Falcon by the USAF (a name loathed by pilots and ground crews), the F-16 is popularly referred to as the "Viper". First introduced into service with the USAF in 1978, the F-16 is a successful all-weather multi-role jet fighter of which more than 4,500 have been built and exported to 25 countries worldwide. It remains in service more than 30 years later. The Viper incorporates a number of innovative design features that include a frameless bubble canopy for better visibility, pilot's side-mounted control stick for ease of control when manoeuvring, a seat reclined 30 degrees to reduce the effect of g-forces on the pilot, and the first use of a relaxed static stability/fly-by-wire flight control system that makes the Viper a highly agile aircraft. At the 'business end' the F-16 has an internal M61 Vulcan cannon and eleven weapon-mounting stations.