Bald Mountain Air Service de Havilland DHC 6 TWIN OTTER accident

The captain and first officer were conducting a flight to provide ongoing logistical support to a remote research camp located on frozen water. The captain reported that departing and arriving flights used an airstrip built on the ice that was lined with snow berms on both sides. He added that, just before the takeoff roll, he and the first officer saw a pedestrian standing near the left side of the departure end of the airstrip. As the takeoff roll continued, the airplane became airborne, so the captain lowered the nose to remain within ground effect and gain airspeed before initiating a climb. The captain added that, as the airspeed increased, he started to climb the airplane and then initiated a left turn. Both pilots reported that, during the turn, they heard a loud thump, which was immediately followed by an aileron control anomaly. The captain initiated a left turn back toward the airstrip and subsequently made an emergency landing. After landing, both pilots saw the pedestrian lying near a snow berm on the left side of the airstrip. The captain reported that he did not remember if it had been prearranged to have the pedestrian stand near the departure end of the airstrip during the departure.

The pedestrian reported that, just before the two pilots boarded the airplane, he told the captain that he would position himself alongside the airstrip so that he could photograph the airplane at departure. As the airplane back-taxied before takeoff, the pedestrian positioned himself clear of the airstrip and behind a 3- to 4-ft-tall snow berm. He said that, as the airplane's takeoff progressed, it did not climb as quickly as it had during previous departures and that the last thing he remembered before the collision was seeing the left wing getting lower to the ground as the airplane began a left turn and flew toward him while continuing to accelerate.

A security video camera recorded the accident sequence, and the recording supported the pedestrian's account of the sequence of events. Although the captain reported that he climbed the airplane before initiating a left turn, the review of the video revealed that the flight crew operated the airplane at a low altitude and along a flightpath that placed it in dangerous proximity to the pedestrian (which was inconsistent with federal regulations) and left no margin to avoid the collision with him.

Verbatim NTSB analysis and probable cause from the NTSB dataset