 The Royal Navy 's airborne early warning ( AEW ) capability had been lost when the Fairey Gannet aeroplane was withdrawn after the last of the RN 's fleet carriers was decommissioned in 1978 . During the Falklands War , a number of warships were lost and casualties suffered due to the lack of an AEW platform . The proposed fleet cover by the RAF Shackleton <unk> was too unresponsive and at too great a distance to be practical . Consequently , two Sea King HAS2s were modified in 1982 with the addition of the Thorn @-@ EMI ARI <unk> / 3 Searchwater LAST radar attached to the fuselage on a swivel arm and protected by an inflatable dome . This allowed the radar to be lowered below the fuselage during flight and for it to be raised for landing . These prototypes , designated <unk> ( AEW ) , were both flying within 11 weeks and deployed with 824 " D " Flight on HMS Illustrious , serving in the Falklands after the cessation of hostilities . A further eight HAS2s were modified to a production standard , known as the AEW2 . Two remained " fitted for but not with " . These entered operational service in 1985 , being deployed by 849 Naval Air Squadron . Three Sea King HAS5 / 6s were later converted as part of the ASaC Mk7 programme , bringing the Mk7 fleet to 13 ; still 3 below the requirement . 
