Bombardier Inc CL600 2D24 N316PQ incident near Detroit, Michigan

Probable cause

The local controller's failure to visually scan and ensure that the runway surface was not occupied by a vehicle or other aircraft before issuing a takeoff clearance to the pilot. Contributing to this incident was the relieved controller's failure to monitor and review the position, after completing the relief briefing, to ensure that nothing had been overlooked.

NTSB analysis

The Local Northwest (LNW) controller cleared Ops 373 (O373), an airport ops vehicle, to drive on runway 22L to conduct a routine inspection. About 90 seconds prior to the incident, and while O373 was operating on the runway, the LNW and Local Northeast (LNE) positions were combined and the LNE controller assumed all LNE and LNW duties. The LNW and LNE controllers conducted a required position relief briefing but did not conduct the briefing at the relieved position in accordance with standard operating procedures.

During the position relief briefing, the LNW controller informed the LNE controller that O373 was driving on runway 22L and at about the same time, Endeavor Air (FLG3860), a CRJ 900, transmitted on the frequency they were ready for departure on runway 22L.

About four seconds after completion of the position relief briefing, at 0802:44, the LNE controller instructed FLG3860 to line up and wait on runway 22L and at 0803:46 cleared FLG3860 for takeoff. About 20 seconds later the Airport Surface Detection System – Model X (ASDE-X) alerted indicating the runway was occupied by both FLG3860 and O373. The LNE controller instructed FLG3860 to "…abort takeoff" and instructed O373 to exit the runway. Both complied with the instruction. ASDE-X data indicated the closest proximity between FLG3860 and O373 was about 211 feet.

The relieved LNW controller did not conduct a required two-minute overlap upon completion of the position relief briefing in order to monitor and review the position to ensure that nothing had been overlooked or incorrectly displayed.

At the time of the incident, the tower was staffed with four personnel; one combined LNE/LNW controller, one combined ground northeast/ground northwest controller, one flight data/clearance delivery controller, and one controller in charge.

Text from the NTSB. Open the NTSB docket for OPS16IA002 for the full record.