The National Transportation Safety Board (NTSB) has posted its Preliminary Report on the runway incursion and near-collision involving a Flexjet Challenger 350 and a Southwest Airlines Boeing 737-800 at Chicago Midway Airport (KMDW). The Feb. 25 incident saw Southwest Flight 2504 (SWA2504) on final approach execute a last-minute go-around from just above the surface as the Challenger taxied across Runway 31C directly in its path. On climb-out from the maneuver, the Boeing passed approximately 200 feet behind the tail of the Challenger after it had crossed the runway and was directed to hold its position by ground control.
In its report, the NTSB cited crew interviews, in which the Flexjet pilots described confusion as to their taxi clearance, which included clearance to turn left and taxi on Runway 04L, cross Runway 31L and hold short of Runway 31C. The pilots testified that, as they turned to taxi on Runway 04L, they were onto Runway 31L before they could “center the nosewheel” from the turn. They also noted that Runway 31L is comparatively very narrow (60 feet wide), matching the width of most taxiways on the airport, which led them to believe that it was a taxiway and that Runway 31C (150 feet wide) in front of them was actually Runway 31L, which they had been cleared to cross. Further confusing the issue, what used to be Runway 31R is now Taxiway H, so there is no longer a Runway 31R.
The crew further testified that their vision was impaired by the low sun, which at 8:48 CST was just 22.4 degrees above the horizon and on an azimuth of 126 degrees from the runway intersection—closely aligned with Runway 13/31C, which was the Southwest flight’s landing direction.
In the seconds the Challenger approached the edge of Runway 13/31C, controllers tried to issue a call to hold short, but the transmission was blocked by another aircraft.
The Flexjet pilots said they did not see a hold short line indicating they were approaching Runway 13/31C, but the NTSB report includes airport-supplied images showing the yellow and black lined markings on the surface of Runway 04L and marker signs on the edge of Runway 04L clearly indicating “Runway 13C Runway 31C.” SWA2504 circled back to land safely, and after a telephone conversation with the tower, the Flexjet flight was cleared for takeoff and continued its flight schedule for the day.
Download the NTSB report here.
