Circumstances:
The aircraft, with two pilots and seven passengers on board was being flown from Stuttgart to Toronto via Shannon, Keflavik and Frobisher. The flight was routine as far as Keflavik. After startup at Keflavik the aircraft remained 18 minutes on the ground before takeoff. Departure was at 2131Z (27 February), and the flight was undertaken at FL390 against a 30 knot wind component, using a GNS-200 on-board navigation system. The aircraft navigation was satisfactory until 2352Z, 285 NM east of Frobisher (approximately 65° N 58° W). At this point the GNS-200 navigation system became unusable for 10 minutes due to a dropout of signals from the very low frequency ground stations on which it depended for operation. The aircraft has been tracked by a military radar network until it neared the Canadian coast. Near the coast the aircraft made a turn to the left of about 20°, but did not subsequently turn back to the right toward Frobisher, as might have been expected. Radar surveillance was not continued beyond that point. The Frobisher main, high power non-direction beacon (FY-206 Khz), went off the air at 0010Z and was restored to service at 0059Z. The standby transmitter failed to operate. At 0013Z, and ATC descent clearance was passed to the aircraft through Frobisher Aeradio; no information was included regarding the status of the radio navigation aids at Frobisher. At 0014Z, the clearance was acknowledged by the flight crew and a descent was commenced. At 0025Z, the flight radioed Frobisher that the radio beacons were not being received; then, that the DME (Distance Measuring Equipment) signals were not being received. The aircraft was at relatively low altitude by this time and lost radio contact with Frobisher. At approximately 0040Z, a small jet aircraft, believed to be CF-BRL, was observed to circle once at low altitude over the radio beacon at Brevoort Island, 120 NM east of Frobisher, and depart in the direction of Frobisher. At 0050Z, at the request of Frobisher Aeradio, an overflying airline jet contacted CF-BRL and learned it was at 4,500 feet (1,372 metres) asl. The pilots were 'lost' and asked whether Frobisher radio beacons were being received. Shortly thereafter, they reported receiving a Frobisher beacon (radio range station, FB 263 KHz, 400 watts) and altering course toward it. They sais they were low on fuel. At 0056Z, the pilot of CF-BRL announced 'both fuel lights are on and we are starting down from 4,500 feet'. The aircraft struck the side of a hill at 0058Z. The wreckage was found 120 km southeast of the destination airport. All nine occupants were killed.
Probable cause:
The following findings were identified:
- During an attempt to locate Frobisher Airport, the aircraft fuel was exhausted by 30 minutes of low altitude maneuvering.
- The descent from cruising altitude was made using navigation information from the on-board GNS system; the crew were unaware that this information was erroneous.
- The main non-directional radio beacon at Frobisher was off the air during a critical phase of the flight; the crew were not informed of this outage prior to commencement of descent.
- The radio beacon transmitter that failed had been fitted with a 40 ampere circuit breaker rather than a 45 ampere circuit breaker specified.
- The standby radio beacon transmitter failed to operate because of a faulty interlock switch system.
- The Frobisher radio range station was operating and suitable for use as a homing beacon; it was not approved for use as a radio range and was not listed on the appropriate Canadian flight navigation charts.
- A Notam issued in August 1973 stated that the Frobisher radio range would be decommissioned 'in approximately two months'; this Notam was still valid at the time of the accident.
- The flight as planned did not comply with the requirements for fuel reserves as expressed in Air Regulation 549.
