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。