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FBI completes investigation into August 2018 crash of stolen DHC-8 near Seattle
9 November 2018

The FBI has completed its investigation of the unauthorized flight of a Horizon Air DHC-8-Q400 aircraft that occurred on August 10, 2018, from Seattle-Tacoma International Airport in Washington, USA. 

Evidence collected during the course of the investigation indicates a 28-year old ground-service agent piloted the aircraft and that the final descent to the ground was intentional. Extensive investigative activity failed to reveal any additional subject(s) involved in the planning or execution of the unauthorized flight.

Flight Data Recorder (FDR) data indicated a significant sideslip on the airplane during the final minute of flight, but the airplane appeared to have remained in control, and the final descent to the ground appeared to have been intentional. If the pilot had wanted to avoid impact with the ground, the FBI stated, he had time and energy to pull the control column back, raise the nose, and initiate a climb. Instead, the controls remained in a position forward of neutral and moved further forward about six seconds prior to the end of the FDR data, which corresponded with the aircraft crash on Ketron Island, Washington, USA.

The Cockpit Voice Recorder (CVR) was recovered, but did not capture any significant sounds beyond the voice communications that the pilot conveyed over the cued microphone. He did not make any phone calls while in the cockpit of the aircraft or make any other statements that addressed his motive.

Interviews with work colleagues, friends, and family – and review of text messages exchanged with the pilot during the incident – did not identify any information that would suggest the theft of the aircraft was related to wider criminal activity or terrorist ideology, according to the FBI. Although investigators received information regarding his background, possible stressors, and personal life, no element provided a clear motivation for his actions.

The events of August 10, 2018, unfolded along this approximate timeline, all in Pacific Daylight Saving Time:

  • 2:36 p.m. – arrival at Port of Seattle-operated employee security checkpoint at Seattle-Tacoma International Airport for his work shift
  • 2:38 p.m. – cleared through employee security checkpoint screening, without any anomalies
  • 7:15 p.m. – arrived in a tow vehicle at Cargo 1, at far north end of Sea-Tac airfield
  • 7:19 p.m. – climbs inside Horizon Air Q400 aircraft #N449QX
  • 7:22 p.m. – begins sequence to start aircraft, and propellers start turning
  • 7:27 p.m. – exits the plane and uses tow vehicle to turn aircraft nose toward the airfield
  • 7:28 p.m. – re-enters the plane
  • 7:32 p.m. – aircraft pulls away from its parked location
  • 7:33 p.m. – aircraft takes off from the airport
  • 8:46 p.m. – FDR data shows end of flight