CHICAGO — Pilots on a Southwest Airlines flight attempting to land at Chicago’s Midway Airport were forced to climb back into the sky to avoid another aircraft crossing the runway on Tuesday morning.

Airport webcam video posted to X shows the Southwest plane approaching a runway just before 9 a.m. Tuesday before its nose abruptly pulls up. A smaller jet is visible crossing the runway that the passenger plane was set to use.

Southwest Flight 2504 safely landed “after the crew performed a precautionary go-around to avoid a possible conflict with another aircraft that entered the runway,” an airline spokesperson said in an email. “The crew followed safety procedures and the flight landed without incident.”

Audio recording of communication between the smaller jet and the control tower recorded its pilot misstating instructions from a ground tower employee, who repeated that the pilot should “hold short” of a runway. About 30 seconds later, the ground tower ordered the pilot “hold your position there.”

The tower employee is then heard saying: “Flexjet560, your instructions were to hold short of runway 31 center.”

Separately, a recording of communication between the Southwest crew and another ground tower employee captured its pilot reporting “Southwest 2504 going around” and following directions to climb back to 3,000 feet.

Seconds later, the audio captures the pilot asking the tower: “Southwest 2504, how’d that happen?”

The second plane, described as a business jet, entered the runway without authorization, said the Federal Aviation Administration.

Flexjet, the plane’s owner, said in a statement: “Flexjet adheres to the highest safety standards and we are conducting a thorough investigation. Any action to rectify and ensure the highest safety standards will be taken.”

Both the FAA and the National Transportation Safety Board say they are investigating.

The Southwest Flight was en route to Midway Airport from Omaha, Nebraska.

Air traffic control audio makes clear that the business jet failed to heed instruction not to cross the runway, said Jeff Guzzetti, a former NTSB member and former FAA investigator.

Guzzetti called it a “very serious runway incursion,” but added: “However, the sky is not falling because last year was the lowest recorded number of serious runway incursions in a decade.”

There were 22 of the serious events in 2023, but just seven in 2024, he said, citing FAA data.

There can be several factors that contribute to these incidents, Guzzetti said: “Was the crew distracted? Was the controller overworked?”

U.S. Secretary of Transportation Sean Duffy said Tuesday afternoon on X that while the NTSB and the FAA are investigating, one thing is clear: “However, it is imperative that pilots follow the instructions of air traffic controllers. If they do not, their licenses will be pulled.”