The Westland Sea King HAR3 entered RAF service in 1978 and the 3A in 1996; both marks of aircraft are used in the Search and Rescue (SAR) role. The aircraft are operated from six locations around the UK, with each location supporting two aircraft. There is also a detachment of two HAR3s providing SAR cover in the Falkland Islands. The SAR squadrons provide 24-hour cover around the UK and the Falkland Islands throughout each year. Each squadron maintains a 15-minutes readiness state during daylight hours and a 45-minutes readiness state during the hours of darkness.