Shortly after arrival, she was involved in the final Exocet raid against the aircraft carrier . In the early hours of 6 June, "Cardiff" shot down a friendly Army Air Corps Gazelle helicopter (no. XX377 of 656 Squadron), in the belief it was a low flying enemy C-130 Hercules. All four on board were killed, the factors contributing to the accident were a poor level of communication between the army and navy, and the helicopter's "Identification Friend or Foe" transmitter had been turned off due to it interfering with other equipment. However a board of inquiry recommended that neither negligence nor blame should be attributed to any individual and that no action should be taken against any individual. The number "205" was later painted at the crash site () as a memorial, the significance being that two of the helicopter's passengers were from 205 Signal Squadron. Approximately an hour after the shoot down, "Cardiff" spotted four landing craft carrying troops from the 2nd Battalion, Scots Guards. Having been told there were no other British forces in the area, "Cardiff's" crew assumed they were Argentine, and fired illuminating star shells over them in preparation to attack. When the Guards saw the star shells and realised "Cardiff"s intentions, the officer in charge of the landing craft, Major Ewen Southby-Tailyour, moved them to shallow water in an attempt to outrun her. "Cardiff", still closing on the craft, signalled to them a single word "friend" via Aldis lamp, Southby-Tailyour responded with "to which side". At this point "Cardiff" "left them alone", neither attacking or assisting them, nevertheless another "blue on blue" incident was avoided.