Guidance is by proportional navigation and a semi-active radar homing system using the nose intake cone and four aerials around the intake as an interferometer aerial, with targets being identified by a Type 1022 surveillance radar (originally radar Type 965) and illuminated by 1 of a pair of radar Type 909. This allows two targets to be engaged simultaneously in initial versions, with later variants (see below) able to engage more. Firing is from a twin-arm trainable launcher that is loaded automatically from below decks. The original launcher seen on the Bristol was significantly larger than that which appeared on the Type 42 and Invincible classes. Initial difficulties with launcher reliability have been resolved.
Sea Dart was used during the Falklands War (1982) and is credited with seven confirmed kills (plus one British Aérospatiale Gazelle helicopter downed by friendly fire). One kill was against a high-flying Learjet reconnaissance aircraft beyond the missile's stated technical envelope. In another engagement, a high-flying Argentinian Canberra bomber was shot down. Other kills were made against low-flying attack aircraft. The net effect of Sea Dart was to deny the higher altitudes to enemy aircraft. This was important because Argentinian aircraft such as the Mirage had better performance than the Sea Harriers, which were unlikely to successfully intercept them. The Argentine losses officially recorded were two A-4 Skyhawks, one Aérospatiale Puma, one English Electric Canberra and one Learjet. Another two A-4 Skyhawks were possibly destroyed.
The two possibles were engaged on the 9th of May 1982 when HMS Coventry became the first Royal Navy warship to fire the Sea Dart SAM (Surface-to-Air Missiles) in anger when the ship fired three on 9 May destroying two A-4 Skyhawks of FAA Grupo 4, with one aircraft found on South Jason Island. Lt Casco and Lt Farias were both killed. The third was fired at a Hercules on a supply run but it escaped unharmed as the Sea Dart was fired at maximum range.
Some reports suggest that these two Skyhawks were lost in bad weather, however Coventry did fire at distant contacts at the same time Lt Casco and Lt Farias were lost and the targets disappeared from radar, but hits could not be confirmed. HMS Broadsword reported that their radar had tracked the missile merging with the pair of Skyhawks. They may well have both been downed by Coventry’s missiles, or collided while attempting to evade it.
The first Authenticated claim was the Puma, on May 9 1982 near Stanley by HMS Coventry and shot down by a single missile, with the loss of 3 men aboard. Three days later, HMS Glasgow was patrolling near Port Stanley with the frigate HMS Brilliant when four A-4s attacked at low level. All but one were shot down by Brilliant's short range Sea Wolf missiles. This was followed by a second wave of four machines and neither Sea Dart nor Sea Wolf functioned to contest these incoming aircraft. Glasgow had a lucky escape when a bomb passed through her flank into the sea without exploding.
The next action saw the sinking of Coventry, on 25 May 1982, and again no Sea Dart was able to engage the A-4s, although one was launched "blind" (without radar control) in an effort to disrupt the enemy attack. HMS Broadsword was unable to engage the aircraft as Coventry had cut across her while making evasive manoeuvres and broken her lock on the target. This time the destroyer was struck by three bombs and sunk. That same day a Super Etendard strike fighter sought to attack the British carrier group with Exocet missiles, but instead struck the cargo ship MV Atlantic Conveyor. Invincible fired six missiles in less than two minutes, but all missed.
On May 30, during the last of the air attacks against the British fleet, the most successful engagements with Sea Dart occurred and Exeter was credited with two A-4s (out of four attackers) downed, despite them flying only 10-15 meters above the sea (theoretically below Sea Dart's minimum engagement altitude of 30 m). One of the two was engaged by a Type 21 frigate with her 4.5 inch gun On June 6 Exeter downed a Learjet 35A that was being used as reconnaissance aircraft, at 12,000 m (12 km) altitude, but missed a second one. Finally, a Canberra was hit on 13 June, again flying at 12,000 m.
In total at least eighteen missiles were launched by Type 42 destroyers, and six by Invincible. Out of five missiles fired against helicopters or high flying aircraft, four were successful, but only two of nineteen fired at low level aircraft hit: just eleven percent; however a number of missiles were fired without guidance to deter low level attacks. Exeter's success can be partially attributed to being equipped with the Type 1022 radar, which was designed for the system and provided greater capability than the old Type 965 fitted to the earlier Type 42s . The Type 965 was unable to cope with low level targets as it suffered multiple path crossings and targets became lost in radar clutter from the surface of the South Atlantic, this resulted in Sea Dart being unable to lock onto targets at distance obscured by land, or fast-moving low-level targets obscured in ground clutter or sea-returns. The Argentinian Navy was well aware of the Sea Dart's capabilities and limitations, having two Type 42s of its own. Consequently, Argentinian planes, opting to fly below the Type 965 radar ("sea skimming"), frequently dropped bombs which failed to explode: The arming vane on the bomb had insufficient time to complete the number of revolutions required to arm the fuze, in which case, the fuze remained in safe mode and would not function on impact.
The Sea Dart Mark 2, GWS 31, (a.k.a. Sea Dart II - not to be confused with Mod 2, above) development was cancelled in 1981. This was intended to allow 'off the rail' manoeuvres with additional controls added to the booster. The Mark 2 was reduced to Advanced Sea Dart, then Enhanced Sea Dart and finally Improved Sea Dart.
Guardian was a proposed land-based system of radars, control stations and a box-launched version of Sea Dart proposed in the 1980s for use as a land-based air defence system for the Falkland Islands. A similar lightweight box-launched version was also proposed for small naval craft.