820 Naval Air Squadron is a Royal Navy Fleet Air Arm carrier-based squadron flying the AgustaWestland Merlin HM2 in an Anti-Submarine role from RNAS Culdrose. The Squadron was formed at RNAS Gosport on 3 April 1933 with the transferral of the Fairey III aircraft from 450 Flight and half of 445 Flight of the Fleet Air Arm of the Royal Navy.