Development started in the late 1950s under licence from Sikorsky. Sea King has been in service for more than 25 years and more than 300 are in service with the Royal Navy, the Royal Air Force, with the navies of Australia, Egypt, Germany, India and Pakistan and the airforces of Belgium, Egypt, Norway and Qatar. It can also be armed with four Mark 11 depth charges. The helicopter can carry two anti-ship missiles, either Sea Eagle or Exocet. Range is 100 km.
Guidance is by inertial navigation system with active radar homing.
Sea Eagle is carried by British and Indian Navy Sea Kings. The missile has inertial guidance with active radar homing. The six flexible bag fuel tanks hold 3,700 litres of fuel which gives the helicopter a range of 1,500 km. For long range operation an auxiliary fuel tank can be fitted internally which extends the ferry range to 1,750 km. The ASW helicopter is equipped with two Type 4 marine markers, two Mark 2 smoke floats and mini-sonobuoys supplied by Ultra Electronics.