1982 British Army Gazelle friendly fire incident

On 6 June 1982, during the Falklands War, the British Royal Navy Type 42 destroyer HMS Cardiff engaged and destroyed a British Army Westland Gazelle helicopter, serial number XX377, in a friendly fire incident, killing all four occupants. Cardiff, on the lookout for aircraft flying supplies to the Argentine forces occupying the Falkland Islands, misidentified the helicopter as an enemy Lockheed C-130 Hercules.

Source: Wikipedia — 1982 British Army Gazelle friendly fire incident (CC BY-SA 4.0)