What happened
At approximately 22:11 Central Daylight Time, Delta Flight 314, operating a Boeing 727 with registration N482DA, received clearance to taxi to Runway 31 at Dallas/Fort Worth International Airport. The controller provided information indicating that Runway 31 was active for operations. Shortly after this communication, Southwest Flight 715, operating a Boeing 737 with registration N50SW, requested and received taxi clearance to Runway 13 for departure.
To accommodate incoming traffic that had requested Runway 13 for landing, Southwest Flight 715, which was positioned at the approach end of Runway 13, was cleared for immediate takeoff. The initial acknowledgment of this takeoff clearance, as received by the tower controller, was garbled and followed by an audible fragment reading "... 715." The tower controller did not realize that both flights had acknowledged the takeoff clearance because Delta Flight 314 was still taxiing toward Runway 31.
Both flights began their departure procedures from opposite ends of the runway. Initially, neither flight crew could see the other aircraft due to a crown in the middle of the runway surface. When the crews finally saw each other, Southwest Flight 715 was approaching V1 speed and elected to continue the takeoff. Delta Flight 314 had just begun its takeoff roll but aborted by turning off onto a taxiway.
An investigation revealed that before departing, when Delta Flight 314 was approaching Runway 31 for takeoff, the first officer believed he had heard clearance for takeoff. The captain of Delta Flight 314 asked the first officer if he was sure, and the first officer replied affirmatively, stating that he had acknowledged the clearance.
The investigation
The investigation focused on the communication protocols between air traffic control and the flight crews involved. It examined the sequence of clearances issued to both Delta Flight 314 and Southwest Flight 715. Key findings centered on the garbled acknowledgment received by the tower controller regarding Southwest Flight 715's takeoff clearance. The investigation also looked into the internal communication within the Delta Flight 314 cockpit, specifically the first officer's misinterpretation of the radio frequency as a direct clearance for his own aircraft.
Findings
The primary contributing factor was a failure in situational awareness and communication verification. The tower controller failed to recognize that both aircraft had acknowledged the takeoff clearance due to the garbled transmission from Southwest Flight 715 and the ongoing taxi activity of Delta Flight 314. Additionally, the first officer on Delta Flight 314 misinterpreted a radio transmission intended for another aircraft as his own clearance, leading to the unauthorized entry onto the active runway.
Safety message
This incident highlights the critical importance of clear communication and positive confirmation of air traffic control instructions. It underscores the need for flight crews to verify that received transmissions are specifically directed to their aircraft before initiating takeoff procedures on an active runway.