No fatalities

Runway Incursion at Chicago Midway: Southwest Airlines 737 and Learjet 45 in Close Proximity

Chicago, IL, United States

On December 1, 2011, a LEARJET INC 45 operated by AIR CLAYCO INC was involved in an aviation accident near Chicago, IL. No fatalities were reported. Investigators recorded the probable cause as: The tower local controller did not ensure that the runway was clear of conflict before directing the B737 to cross the runway, and other air traffic control personnel did not effectively intervene when the separation between the two airplanes became… This summary draws on records from NTSB; 12 related events involving the same aircraft type or operator are linked below.

SourcesNTSBPrimary reportUpdated 2026-08-03Data APIEditorial standards

On December 1, 2011, a runway incursion occurred at Chicago Midway when a Southwest Airlines 737 crossed runway 31R as a Learjet 45 was taking off. The closest lateral distance was 287 feet, vertical 62 feet. The ASDE-X system did not alert.

Incident Overview

At 0907 on December 1, 2011, a runway incursion and operational error took place at Chicago Midway International Airport (MDW). The incident involved Southwest Airlines flight 844 (SWA844), a Boeing 737-700, and Gama Charters flight 17 (GAJ17), a Learjet 45.

Sequence of Events

After landing on runway 31C, the crew of SWA844 was instructed to cross runway 31R and contact ground control. At the same time, GAJ17 was cleared for takeoff on runway 31R. As the B737 crossed the hold-short line for runway 31R at taxiway N, the two aircraft conflicted. The first officer of SWA844 observed the Learjet departing and warned the captain, who was at the controls, to stop. The captain halted the B737 short of the runway edge. Air traffic control did not take any actions to resolve the conflict. After the incident, the captain of SWA844 stated that the departing Learjet had overflown his aircraft.

Recorded FAA data showed that the closest proximity between the Learjet and the B737 was 287 feet laterally and 62 feet vertically. Although MDW is equipped with an Airport Surface Detection Equipment – X (ASDE-X) ground movement safety system that includes conflict detection and warning capability, the system did not sound an alarm during the incident.

Weather Conditions

The 0851 weather observation for MDW reported wind from 180 degrees at 4 knots, visibility 10 statute miles, few clouds at 15,000 feet AGL, broken clouds at 20,000 feet AGL and 25,000 feet AGL, temperature 1°C, dew point -4°C, and altimeter 30.26 inches of mercury.

Additional Information

For further information, see the Air Traffic Control Group Chairman's Factual Report included in the docket for this incident.

Contributing factors

ATC personnel