The Royal Navy deployed to the Falklands with four main surface-to-air weapons for defence against air attacks. The oldest was the Seaslug missile, fitted to the County Class destroyers Antrim and Glamorgan. This was a first-generation area-defence SAM, with the genesis of its development taking place in the late 1940s. By 1982, it was greatly obsolete, and it would only be fired in the anti-aircraft role once. Its replacement was the more modern Sea Dart, fitted to the Type 42 destroyers, HMS Bristol and the carrier Invincible. Sea Dart was modern and effective, but had difficulties engaging low-level targets, especially at close range. This gap was filled by point-defence missiles, of which the RN had two. The older of the two was Seacat, widely fitted to older ships. Seacat was fairly effective, but was slow and each mounting could only guide a single missile at a time, reducing its effectiveness against multiple targets. Its replacement, fitted to the Type 22 frigates Broadsword and Brilliant (and the older Andromeda), was Sea Wolf. Sea Wolf was a fast, effective missile, but it had primarily been designed as an anti-missile missile. This induced several issues with the guidance computer when engaging aircraft. Ships were also fitted with one or two 4.5in guns and a number of 40mm or 20mm autocannon; these were generally seen as anti-ship weapons, but could be used against aircraft targets.

These weapons had largely been designed to engage Soviet targets in the North Atlantic in the event that the Cold War turned hot. These targets would have been the large, fast, high-flying bombers and missiles that NATO expected would try to hit its convoys in the Atlantic. The radars and missiles were optimised to detect and attack these targets. The Argentinians, however, were not using supersonic, high-flying aircraft or missiles. Instead, they were using the slow-flying, sea-skimming Exocet missile and low-flying aircraft. The Argentinian Navy operated the Type 42 destroyer and Sea Dart as well, and thus were able to brief Naval and Air Force strike pilots about the weaknesses of the system. The RN understood these threats, especially the threat from Exocet, which only Sea Wolf was expected to be able to shoot down. However, experience with Exocet in exercises indicated that chaff was an effective defence against it. Assessments of the Argentinean threat made as the British Task Force set off for the Falklands were cautiously optimistic, suggesting that the air threat was 'only moderate. The Argentines will need luck on their side if they are to inflict substantial damage on the Task Force.' Exercises within the Task Force as it headed south moderated this outlook, revealing the difficulties the RN had in tracking and engaging low-flying or sea-skimming targets.

The Royal Navy's first loss in the Falklands was the Type 42 destroyer Sheffield, struck by an Exocet on the 4th May 1982. This was generally not seen as being the result of failings in her anti-aircraft systems. but instead as being the result of complacency aboard. The main method of detecting Exocet attacks was by detecting emissions from the Agave targeting radar aboard the Etendard aircraft that carried it, using the UAA-1 Abbey Hill radar detector. However, on the Type 42s, the satellite communication system (SCOT) caused interference with Abbey Hill when in use. Sheffield's captain allowed the SCOT system to be used in daytime, when Exocet attacks were most likely; the captains on other Type 42s limited use of SCOT to nighttime only. Glasgow did detect emissions from the Agave radars on the attacking aircraft, but the response to this was slow, as there had been a number of false alarms in the preceeding days. The air defence officer was in the wardroom getting coffee and his assistant was in the heads, instead of in the operations room, further delaying the response. When the air defence officer returned, he dismissed the threat, believing that the ship was outside Etendard range, due to a misreading of intelligence reports. The only definitive warning the ship had was when a visual sighting of the missiles was made, a few seconds before impact. No attempt was made to launch chaff, or engage the missile. The main conclusions drawn from her loss were the need to keep on high alert in danger areas, and to reduce reaction times. However, her loss also indicated the need for a close-in weapons system (CIWS) to be fitted to ships to provide a last line of defence.

On the 12th May, the Type 42 destroyer Glasgow and Type 22 frigate Brilliant were attacked by aircraft in between bombardments of Port Stanley. They were attacked by two waves of four A-4 Skyhawks, coming in at low altitude. The first wave was detected by Glasgow, which prepared to engage with Sea Dart. However, there was an issue with the computers, and the launcher refused to load any missiles. Next, Glasgow's 4.5in gun was tried. This jammed after eight shots. Brilliant engaged with Sea Wolf, shooting down three successfully. The second wave approached twenty minutes later, weaving to confuse British gunners. Glasgow's gun and Sea Dart were still inoperable, so Brilliant's Sea Wolf was the only weapon that could engage. However, the system, intended to target missiles that moved simply and straightforwardly, was confused by the weaving and refused to engage. Fortunately, only one bomb hit Glasgow, and that was a dud. This attack pointed to a number of programming issues with the computers on Sea Dart and Sea Wolf. These were worrying, but were much more easily fixed than hardware problems.

The next set of major attacks on British ships came on the 21st May. These concentrated on ships in the vicinity of the landings in San Carlos Water. These were mostly older ships, but also included both Type 22s. The defences of the ships were supplemented by the troops ashore, using Rapier SAMs and Blowpipe handheld missiles, as well as machine guns. These forced off several probes, but at about 9:35am Antrim took the first hit, a dud which started several minor fires. A second wave was the target of the only Seaslug launch - an unguided missile that was being jettisoned to reduce the risks from the fires. Her Seacat missile was out of action, and her guns couldn't stop the attack. Fortunately, every bomb missed, though cannon fire did some damage. At 1:30pm, the Leander-class frigate Argonaut was attacked by six Skyhawks. These had gone undetected by the British force, who had been distracted by an engagement with another force to the west, as well as the low-level approach of the Argentinean aircraft. Argonaut, taken by surprise and poorly armed against air threats, took two bomb hits. While both were duds, they did serious damage. At 1:45, the Ardent, patrolling the south-western approaches to San Carlos, was attacked by several low-flying Skyhawks. These approached from astern, where her guns and Seacat couldn't engage them. Her captain manouvred to bring the aircraft within Seacat's firing arc, but by this time, the aircraft were too close for Seacat to track them (the sight had to be depressed below safety limits). This attack scored three hits (two of which exploded), which destroyed the Seacat and caused electrical damage that knocked out the 4.5in gun. This left her practically defenceless against the next attack, at 2:06. This achieved several hits and near misses, causing major damage, fires and minor flooding. One of the bombs killed most of her after damage control party, making it much harder to fight the fires. She was soon abandoned, and left to burn. Both Argonaut and Ardent were largely alone and taken by surprise. Both ships depended mainly on Seacat for their air defence. This system was obsolete, and insufficient for attacks by multiple fast-moving aircraft, especially at low-level. The ships in the sound, protected by the more effective Rapier and Sea Wolf, came through largely unscathed.

This would not hold for long. On the 23rd, Antelope and Brilliant were attacked by four Skyhawks, attacking in two waves of two. The first wave made their approach, but were forced off by a heavy barrage of fire. This drew the attention of the British defenders, allowing the second wave, approaching from a different direction, to score a hit on Antelope. Meanwhile, one of the first wave had turned back, and in the confusion, scored another hit on Antelope. Neither bomb exploded. Other attacks that day failed to score hits, due to British fire. Bomb disposal teams boarded Antelope to defuse the bombs, but one exploded as they were working on it. This started major fires that would eventually spread to the magazine, sinking the ship. Antelope's loss was similar to that of her sister ship Ardent; neither ship had sufficient warning to engage their attackers, and Seacat was an insufficient system in either case. The next day, the Argentinians made a low-level attack on San Carlos with seventeen aircraft in loose cohesion. Flying at low level over terrain, they managed to evade radar detection. The ships in the bay had only a few seconds warning of the first attacks. This allowed the Argentinians to score hits on the landing ships Sir Lancelot and Sir Galahad, doing relatively serious damage to the former.