Flight Background
Buffalo Air Flight 526 was a Douglas DC-3C freighter based in Yellowknife, Northwest Territories, tasked with hauling jet fuel to support forest fire suppression operations. The aircraft conducted shuttle flights between Fort Simpson and Trout Lake, transporting 17 drums of Turbo-B jet fuel per leg.
Sequence of Flights
Before departure from Yellowknife, the flight crew checked en route weather and filed a company flight itinerary. The aircraft had been fueled the night before with approximately 436 imperial gallons: full main tanks (336 imp. gal.) and 100 imp. gal. in auxiliary tanks. The first officer confirmed the quantity using a dip-stick. At 07:40 mountain daylight saving time, the aircraft departed Yellowknife under visual flight rules (VFR) with 17 full drums on board. It landed at Trout Lake at 09:25, offloaded the drums, and departed for Fort Simpson at 09:45. After landing at Fort Simpson at 10:20, another 17 drums were loaded, and the aircraft departed at 10:49, climbing to 3,500 feet asl with engines set to 575 bhp. It landed at Trout Lake at 11:20, offloaded, and departed again at 11:35, landing at Fort Simpson 35 minutes later.
Fuel Management Issues
While cargo was being loaded at Fort Simpson, the flight crew discussed differing fuel calculations. The first officer believed the aircraft required fuel, but the captain calculated sufficient remaining. The captain decided to refuel on the next shuttle flight. Despite considering cockpit fuel gauges unreliable, the captain requested the first officer confirm fuel quantity with a dip-stick. At 12:28, the aircraft departed Fort Simpson climbing to 5,000 feet asl. About eight minutes later, fuel pressure fluctuations indicated empty auxiliary tanks. The captain switched to main tanks and asked about dip-stick measurements; the first officer reported he had not checked because the dip-stick was missing. The captain estimated 45 minutes of fuel remaining. After landing at Trout Lake at 13:00, 31 empty drums were loaded, and the aircraft departed at 13:25. The first officer was pilot flying, with the captain as pilot not flying.
Final Approach and Crash
Twenty miles southwest of Fort Simpson, the pilot not flying reported position to Fort Simpson Flight Service Station (FSS) and requested fuel on arrival. At 10 miles, they updated position and received airport advisory. Approximately six miles from the airport at 400–500 feet agl, the pilot flying reported left engine fuel pressure loss. The left engine lost power. The pilot not flying switched the boost pump on and moved the fuel selector to left auxiliary, then right auxiliary; the engine regained power momentarily but failed again. Realizing three of four tanks were empty, the captain took control and headed for runway 31. As he called for the engine failure checklist, the first officer reported right engine power loss. With both engines inoperative and insufficient altitude to reach the airport, the first officer notified FSS of an attempted landing on the Mackenzie Highway north of the Liard River. The approach to the road was unsuccessful, and the aircraft crash-landed into a treed area. Witnesses at the Liard River ferry crossing observed the aircraft at about 40 feet agl, heading northwest with landing gear extended, and heard engines cutting in and out before it disappeared behind trees. The aircraft struck trees and crashed approximately 1/2 nautical mile short of runway 31. Total flight time since last refueling was about 4 hours 37 minutes.
Probable Cause
The official investigation determined that the flight was commenced with a fuel quantity below the minimum requirements, resulting in loss of engine power because of fuel exhaustion. Contributing to the occurrence was the lack of flight crew coordination.