What happened
During the takeoff phase at the airport, a Mitsubishi MU-2 was cleared by the ground controller to taxi from its parking position on the northeast side of the field to runway 35. The flight path involved taxiway A, taxiway D, crossing runway 26, and proceeding to taxiway K.
Approximately one minute after the MU-2 received its taxi clearance, the same ground controller authorized a maintenance tug, which was towing an MD-80, to taxi from the northeast ramp to a ramp on the west side of runway 35. This clearance specifically included permission for the tug to cross runway 35.
Upon reaching the runway, the pilot of the MU-2 contacted the tower controller and received takeoff clearance. As the aircraft reached an airspeed of 80 knots, the pilot observed the maintenance tug crossing the runway centerline. The pilot attempted to abort the takeoff and maneuvered the aircraft to the left side of the runway; however, the MU-2 collided with the tug at the intersection of runway 35 and taxiways Golf and Echo.
The investigation
At the time of the accident, three air traffic controllers were operating in the tower cab: a local controller, a ground controller, and a clearance delivery controller. FAA regulations require that a ground controller must receive approval from the local controller before authorizing any aircraft or vehicle to cross or use any part of an active runway. Furthermore, airport standard operating procedures dictate that all runway crossing authorizations and coordination must be completed via a recorded landline.
Findings
An investigation of controller interviews and recorded voice communications revealed that the ground controller failed to coordinate the maintenance tug's runway crossing with the local controller.