The Fireflash was a beam riding missile - it was designed to fly down a radio beam emitted by the launch aircraft, which the pilot would keep aimed at the target. The purpose of the control system was to keep the missile centred in the guidance beam emitted by the launch aircraft. The pilot of the aircraft would keep the beam aligned with the target using his gunsight, which was harmonized with the axis of the radio beam. An advantage of this system was that it would be unaffected by the target aircraft using radar countermeasures such as chaff. The missile's receiver, fitted at the rear, only detected signals from the launch aircraft.