Chicago ORD Tower Controller Prevents Midair Collision

A close call at Chicago's O'Hare International Airport around midday last Friday demonstrated again the risks of operating at airports that use parallel runways for simultaneous arrivals and departures. The aircraft involved were an American Airlines Boeing 737 that had just departed Runway 9 Right and an Envoy Embraer 145 that took off from the parallel Runway 10 Left. ORD uses two sets of parallel runways that include Runways 9 Left and Right on the north side of the airport and Runways 10 Left, Center and Right on the south side. In this incident, both aircraft were issued a 100 degree heading after takeoff.

For some as yet unknown reason, the Envoy pilot off Runway 10 Left began a left turn toward the American 737 climbing off the parallel. A sharp-eyed tower controller at ORD first attempted to prevent a collision by telling the Envoy crew to stop its climb, but the crew did not respond. The controller’s next transmission did get the pilot’s attention, “Envoy 4603 turn right immediately heading 140.” The Envoy crew acknowledged and began a turn back to the southeast.

Adding to the complexity of this situation is that traffic using Runway 10 is controlled by personnel in one control tower, while traffic off the north runways is handled by controllers in another tower on the airport's north side. The FAA is investigating the incident. Both American Airlines and Envoy have agreed to cooperate with the investigation.