NTSB Probes Runway Incursion at Chicago Midway

DALLAS — On February 25, 2025, at approximately 8:48 AM CST, a runway incursion at Chicago Midway International Airport (MDW) sets off an intensive investigation by the National Transportation Safety Board (NTSB). 

Two flights were involved: Southwest Airlines (WN) flight 2504—a Boeing 737-800 on an ILS approach—and Flexjet flight 560—a Bombardier Challenger 350 taxiing for departure. Neither aircraft sustained damage, and all 145 occupants emerged uninjured. ​

Incident Overview

According to the preliminary report, WN flight 2504 was cleared for an instrument landing system (ILS) approach to runway 31C in visual meteorological conditions. As the flight neared touchdown, its crew spotted what they believed was a general aviation aircraft taxiing perpendicularly to the runway. 

However, when the crew heard an audible “100 ft” call, they realized that the Flexjet flight 560 aircraft was not stopping but proceeding onto the active runway. With less than 200 feet of lateral separation between the two airplanes’ GPS antennas, the Southwest flight promptly executed a go-around, avoiding a potentially hazardous situation. ​

Flexjet’s Taxiing Dilemma

Flexjet Flight 560’s narrative of the event paints a picture of operational confusion. The crew had completed all pre-flight procedures and received taxi instructions from Midway’s ground control. Initially routed via taxiway F with a hold-short clearance, the crew later encountered revised instructions that involved turning onto runway 04L, crossing runway 31L, and holding short of runway 31C. 

The pilot noted that glare from the rising sun and the similarity in markings between taxiways and runways compounded their difficulty in identifying the correct hold short line. This misinterpretation ultimately led them to inadvertently enter the active runway area just as the Southwest flight was on final approach. ​

Investigation, Data Collection

In the wake of the incident, the NTSB—prompted by Southwest Airlines and Flexjet notifications—launched an investigation involving multiple parties. Among those assisting were the Federal Aviation Administration (FAA), representatives from the involved airlines, the WN Pilots Association (SWAPA), Boeing, and an accredited representative from the Transportation Safety Board of Canada. 

Flight data recorders and ADS-B data were collected for analysis, though both airplanes’ cockpit voice recorders had been overwritten. Additionally, photographs of the runway’s hold-short markings, provided by MDW Operations, have been used to assess the scene. ​

Environmental, Operational Conditions

Meteorological conditions at the time were favorable, with clear skies, visibility of approximately 11.5 miles, and light winds from the northwest at 8 knots. 

However, the sun’s position—approximately 22.4° above the horizon—likely contributed to the difficulty distinguishing runway markings, as reported by the Flexjet crew. ​

Ongoing Inquiry

While both flights completed their respective operations safely—WN flight 2504 eventually landed, and Flexjet flight 560 departed after a brief delay—the incident has raised important questions regarding taxi route instructions and runway marking visibility at Midway. 

The NTSB’s investigation is ongoing as the board gathers data from flight recorders, crew interviews, and ground operations to determine the root causes and any necessary safety enhancements.

Details in the report remain preliminary and subject to change as further analysis unfolds.

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