Incident Overview
Description
A de Havilland DHC-6-100 Twin Otter turboprop plane was destroyed when it crashed on takeoff from the gravel airstrip at Muncho Lake, BC, Canada. A post-impact fire erupted and the airplane was destroyed. One passenger was killed. Two pilots and two passengers survived the accident. The airplane was operating on a VFR flight to Prince George Airport, BC (YXS). After becoming airborne, the aircraft entered a right turn and the right outboard flap hanger contacted the Alaska Highway. The aircraft subsequently struck a telephone pole and a telephone cable, impacted the edge of the highway a second time, and crashed onto a rocky embankment adjacent to a dry creek channel. The aircraft came to rest upright approximately 600 feet from the departure end of the airstrip. The airstrip was located at a lodge next to Muncho Lake. It was maintained by the operator, Liard Air. It was 950 feet long and sloping upward about 2ø in the northwest direction. Post-accident calculations showed that the aircraft probably weighed 10100 pounds at takeoff, which was below the 11 579 pounds maximum takeoff weight. However, centre of gravity (c of g) calculations revealed that the aircraft c of g was near the forward limit, at 23 per cent mean aerodynamic chord (MAC). The approved c of g range is between 20 per cent and 36 per cent MAC. FINDINGS AS TO CAUSES AND CONTRIBUTING FACTORS: 1. The take-off was attempted at an aircraft weight that did not meet the performance capabilities of the aircraft to clear an obstacle and, as a result, the aircraft struck a telephone pole and a telephone cable during the initial climb. 2. A take-off and climb to 50 feet performance calculation was not completed prior to take off; therefore, the flight crew was unaware of the distance required to clear the telephone cable. 3. The southeast end of the airstrip was not clearly marked; as a result, the take-off was initiated with approximately 86 feet of usable airstrip behind the aircraft. 4. The take-off was attempted in an upslope direction and in light tailwind, both of which increased the distance necessary to clear the existing obstacles.
Primary Cause
Initial takeoff performance did not meet the aircraft’s capabilities to clear an obstacle, leading to a collision with a telephone pole and cable.Initial takeoff performance did not meet the aircraft’s capabilities to clear an obstacle, leading to a collision with a telephone pole and cable.Share on:
