Incident Overview
On March 23, 2006, at 0907 Central Standard Time, a runway incursion took place at Chicago O'Hare International Airport (ORD) during daylight visual meteorological conditions. The incident involved United Airlines (UAL) flight 604, a Boeing 737-300, and UAL1520, an Airbus A-320.
Sequence of Events
The north local controller cleared UAL604 for takeoff from runway 4L. At the same time, UAL1520 was crossing that runway. The co-pilot of UAL604 observed the A-320 moving rapidly toward the runway and aborted the takeoff. The co-pilot then informed the controller that they were aborting the takeoff because of the crossing traffic. According to the co-pilot, the aircraft did not exceed taxi speed during the aborted departure.
Separation and System Status
Separation between the two aircraft was lost, with the closest proximity being approximately 600 feet—the distance from the approach end of runway 4L to taxiway H. The Airport Movement Area Safety System (AMASS) did not activate during the incident.