Incident Overview
A United Airlines Boeing 727 domestic passenger flight was holding short of Runway 32L at Chicago-O'Hare International Airport, awaiting clearance for an intersection takeoff. Simultaneously, a Northwest Airlines Boeing 747 international passenger flight was holding in position at the end of the same runway, awaiting takeoff clearance.
Sequence of Events
The control tower cleared the Northwest flight for takeoff, and its crew commenced the takeoff roll. The United flight, under the mistaken belief that they had also been cleared for takeoff, taxied onto the runway and began their ground roll. The tower controller observed the incursion and instructed the Northwest flight to abort its takeoff. The United flight also aborted its takeoff. Both aircraft subsequently taxied off the runway without further incident.
Outcome
No injuries or damage were reported. The aircraft involved were a United Airlines Boeing 727 and a Northwest Airlines Boeing 747. The event occurred at Chicago-O'Hare International Airport.