What happened
On March 20, 2018, a de Havilland DHC-6 Twin Otter, registration N716JP, struck a pedestrian following takeoff from a remote sea ice airstrip approximately 140 miles north of Deadhorse, Alaska. The flight, operated by Bald Mountain Air Service, Inc., was performing a 14 CFR Part 135 VFR on-demand commercial flight to provide logistical support for the ICEX 2018 exercise.
Prior to takeoff, the crew observed a pedestrian standing near the left side of the departure end of the airstrip. During the takeoff roll, the captain applied differential engine power to correct a slight veer to the left of the centerline. After becoming airborne, the captain maintained the aircraft within ground effect to gain airspeed before initiating a climb and a subsequent left turn. During this turn, the crew heard a loud thump and experienced an aileron control anomaly. The captain performed an emergency landing to the north.
The pedestrian, an employee of the Arctic Submarine Laboratory, had positioned himself behind a snow berm to photograph the aircraft's departure. He reported that the aircraft's left wing lowered toward the ground as it began the left turn, leading to the collision. The pedestrian sustained serious injuries to his head and neck.
The investigation
An examination of N716JP revealed substantial damage to the left wing and left aileron. A review of security video footage from a nearby camp structure confirmed the sequence of events, showing the aircraft flying at a low altitude and performing a steep left turn that placed the wing in direct contact with the pedestrian.
While the captain stated he had climbed the aircraft before turning, the video analysis indicated the flight path was at a low altitude and in dangerous proximity to the pedestrian. The cockpit voice recorder (CVR) was recovered but failed to capture the events of the accident.