Tempers flared in the cockpit of a Southwest Airlines Boeing 737 after landing at Chicago's Midway airport on 1 December and being given clearance by the tower to cross a parallel runway en route to the terminal as a Learjet was preparing to take off.
"We just had a plane take off on [runway] 31R - you cleared us to cross!", one of the Southwest pilots exclaimed to the tower controller, according to an audio recording of the incident available on LiveATC.net
According to the US National Transportation Safety Board (NTSB) preliminary report, the controller had cleared a Learjet 45 business jet to take off on Runway 31R as Southwest flight 844 was rolling out on the parallel Runway 31C. The controller then cleared the Southwest plane to cross Runway 31R.
"The first officer of the [Boeing] 737 saw the [Learjet 45] departing runway 31R and yelled for the captain, who was at the controls, to stop," the NTSB said. "The captain stopped the  short of the runway edge."
Investigators said the Learjet passed within 87m (287ft) laterally and 18.9m vertically of the 737 at the closest point.
"I want you to acknowledge you cleared us to cross 31R," demanded one of the Southwest pilots to the tower controller after the incident. The controller responded back for the pilots to contact ground control.
"We had to hit the brakes and this thing went right over our heads," the pilot then said to the ground controller as the aircraft taxied to its gate. "We're going to put in a report."