The D/F Emergency organisation exists to help pilots who experience problems when aloft be they minor or major. The D/F Emergency organisation co-operates with both the military (RAF) and civil aviation authorities, and indeed any organisation that is concerned with search and rescue. Two major incidents are portrayed in the film, illustrating the work of the D/F Emergency organisation.
Film with views of several D/F antenna sites around Britain. Cut to a Hunter aircraft, out of control and tumbling in the cloudy sky. Camera follows the Hunter down, as the pilot transmits a mayday signal 'Hunter mission 14; out of control, I have to bail out, over'. Cut to several D/F stations who have received his signal; by means of triangulation the location of the transmitting aircraft is determined. The nearest D/F station, Preston, replies to mission 14, advising he is 8 miles due west of Anglesey. Preston contacts RAF Anglesey who dispatch a rescue helicopter (XJ430) and a RAF rescue launch (2743). Film of both services setting out to sea. As a precaution, the civil police and mountain rescue are alerted. The helicopter is first to reach the pilot in his dinghy, the winch-man descends on a cable, secures a harness to the pilot, and they are both lifted safely to the helicopter. The commentary explains how the D/F service can help to save lives; the service was established to help pilots who may be in difficulties, however slight.
A detailed description of the services' structure is given; The five air traffic control centres in the United kingdom and their associated master airfields are available to accept aircraft in trouble via a permanent emergency frequency of 121.5 megacycles (mHZ). If more than one D/F station receives an emergency signal, the location of the transmitter is displayed on a large map of the UK as the intersection of two or more lines of light from the five cathode ray projectors, associated with the control centres. At the control centre, the regional controller can speak directly to the pilot to provide all the information he requires, and is able to mobilise the appropriate emergency service.
Three grades of emergency calls are available; Securite, Pan Pan and Mayday; each is explained in detail, and illustrated with re-enactments of past accidents. A Jet Provost pilot disorientated requests a course for an RAF station in Gloucestershire.
A Hunter aircraft in thick cloud has nearly been hit by lightning; the gyro-compass has tumbled and the pilot is uncertain of his position; pilot calls 'pan, pan, mission 76, requests landing at the nearest airfield'. Pilot is told to reset gyro and set course for Church Fenton, where the control tower, fire and ambulance services wait by the runway. The Hunter clears the runway and lands.
Mayday is transmitted when an aircraft is about to crash. Communications pilot/control centre may be limited or non existent, resulting in delay before the rescue services arrive at the crash site. In one year, over 2,000 actual emergencies used the 121.5 mHZ service. It exists to help both civil and military pilots. The narrator urges pilots to acquaint themselves with the service, and discover how it works. Film closes with the Jet Provost en route to Gloucestershire.