Flight Details
The Fokker F-27, registration YN-BZF, was engaged on a delivery flight from North Yemen to Nicaragua. Two 200 US gallon auxiliary ferry fuel tanks had been installed in the cabin for extended range. The aircraft departed on 11 April 1985 from North Yemen (Sanaa) and proceeded via Saudi Arabia (Jeddah), Egypt (Cairo), Greece (Athens), Italy (Genoa), and Scotland (Prestwick). On 20 April 1985, the flight left Prestwick, stopped at Stornoway, and arrived at Reykjavik, Iceland at 15:48 hours.
Fuel System Issues
During the preceding flight segments, the crew had been unable to retrieve fuel from the auxiliary ferry fuel system. While at Reykjavik, they checked the system and found it to be in working order. Icelandic F-27 engineers also inspected it; they noted that the system "was not very professionally looking" and "got the feeling that the crew was not quite certain of how to operate it". They advised the crew on operation and suggested a ground run. After receiving weather information and ATC clearance, the crew took off at 17:21 hours, heading for Kangerlussuaq-Søndre Strømfjord Airport.
At 18:32, the Pilot-in-Command transmitted a message to Iceland radio, extending thanks to the Icelandic engineers and reporting that the auxiliary fuel system was working correctly. This message was sent prior to passage of Kulusuk at 19:35 hours. During the flight from Reykjavik to Greenland, the crew informed air traffic control that problems had arisen with retrieving fuel from the auxiliary system. At 19:50, approximately 50 nautical miles west of Kulusuk, the crew radioed the radar station BIG GUN about fuel problems, stating that the auxiliary system did not function after all. The fuel reserve was reduced by approximately 400 US gallons, and with a ground speed of only 180 knots, the crew decided to return for a landing at Kulusuk Airport.
Accident Sequence
Due to deteriorating weather conditions, the crew could not locate the aerodrome. The flight then diverted westbound for an emergency landing at a radar station called "SOB STORY" on the icecap. During descent, the aircraft collided with the icecap.
Investigation Findings
The investigation reported that the crew was properly certified. Normal aircraft systems, except for the flight data recorder and the cockpit right front window electrical deicing system, were functioning normally, confirmed by on-site investigation. The auxiliary ferry fuel system was not functioning properly, though the cause was not conclusively established. The crew did not undertake a satisfactory functional airborne check of the auxiliary system prior to its essential use. The department opined that a deficiency in the procedures applied for operating the system may have been a major factor. Weather conditions were a major factor at the time of the approach and at the accident site. The AFIS operator incorrectly stated the distance from the KK NDB as 10 NM instead of 3 NM, but the lack of this information did not appear to have an important bearing on locating the aerodrome. Search and rescue was anticipated early and initiated immediately after the accident, but low visibility and approaching darkness precluded successful rescue on the first attempt.