- Date
- December 1, 2011, 09:07 local (14:07 UTC)
- Place
- Chicago, IL
- Injuries
- 85 uninjured
- Phase of flight
- Takeoff
- Defining event
- Takeoff: Runway incursion veh/AC/person
- Weather
- Visual (VMC) · Day
- Status
- Completed · report November 7, 2012
- Report
- Approved by Office Director
- NTSB office
- Operational Factors Division
- Parties
- Federal Avaition Administration, Federal Avaiton Administration, Federal Avation Administration
- Case key
- 82486
From the NTSB’s public API. By law, NTSB reports can’t be used as evidence in lawsuits over the incident.
On this page
Probable cause
The NTSB’s determination of the probable cause, and any contributing factors.
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 questionable.
Findings · 6
NTSB’s coded findings. Those marked are part of the probable cause; the rest are factors or other findings.
Analysis
A runway incursion occurred when a Boeing 737-700 (B737) was cleared by a tower local controller to cross a runway immediately after a Learjet 45 was cleared for takeoff on the same runway. The first officer of the B737 saw the departing Learjet and warned the captain, who stopped the B737 short of the runway edge. Air traffic control personnel did not take any actions to resolve the conflict between the two airplanes. Recorded data indicated that the Learjet passed within 287 feet laterally and 62 feet vertically of the B737.
Factual narrative
At 0907 on December 1, 2011, a runway incursion and operational error occurred at MDW when Southwest Airlines flight 844 (SWA844), a Boeing 737-700, was cleared to cross runway 31R immediately after Gama Charters flight 17 (GAJ17), a Learjet 45, was cleared for takeoff on the same runway. After landing on runway 31C, the crew of SWA844 was instructed to cross runway 31R and contact ground control. GAJ17 was departing from runway 31R at the time, and conflicted with SWA844 as the B737 crossed the hold-short line for runway 31R at taxiway N. The first officer of SWA844 saw the Learjet departing runway 31R and warned the captain, who was at the controls, to stop. The captain stopped the B737 short of the runway edge. Air traffic control did not take any actions to resolve the conflict between the two aircraft. After the incident, the captain of SWA844 said that the departing Learjet had overflown his aircraft. Recorded FAA data indicated that the closest proximity as the Learjet passed 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 included conflict detection and warning capability, the system did not sound an alarm during the incident. The 0851 weather observation for MDW was wind 180 degrees at 4 knots, visibility 10 statute miles, few clouds at 15,000 feet above ground level (AGL), broken clouds at 20,000 feet AGL, broken clouds at 25,000 feet AGL, temperature 1 degree Celsius, dew point minus 4 degrees Celsius, altimeter 30.26 inches of mercury. For further information, see the Air Traffic Control Group Chairman's Factual Report included in the docket for this incident.
Sequence of events
The events NTSB coded, in order, by phase of flight. The defining event is the one that best describes the accident.
N570AM · Learjet 45
Runway incursion veh/AC/personDefining eventN432WN · Boeing 737-7H4
Runway incursion veh/AC/personAircraft · 2
- Registration
- N570AM
- Reported as
- Learjet 45
- Category
- Airplane
- Serial number
- 238
- Engines
- Honeywell TFE-731-SER, 4,000 lbs thrust, turbo fanHoneywell TFE-731-SER, 4,000 lbs thrust, turbo fan
- Damage
- No damage
- Flight
- Part 91
- Operator
- Air Clayco Inc
- Registered owner
- Air Clayco Inc
- Departed
- Chicago, IL
- Destination
- SAV · Savannah, GA
- Flight plan
- IFR
- Airport
- MDW · Chicago Midway, runway 31R, 5,141 × 150 ft
Matched to the registry by N-number and the event date; the registry’s history has gaps, so older matches can be wrong. Compare the reported make and model.
- Registration
- N432WN
- Reported as
- Boeing 737-7H4
- Category
- Airplane
- Serial number
- 33715
- Engines
- CFM Intl. CFM56 SERIES, 2,200 horsepower, turbo fanCFM Intl. CFM56 SERIES, 2,200 horsepower, turbo fan
- Damage
- No damage
- Flight
- Part 121
- Operator
- Southwest Airlines Co
- Registered owner
- Southwest Airlines Co
- Departed
- MSP · Minneapolis-St, MN
- Destination
- Chicago, IL
- Flight plan
- IFR
- Airport
- MDW · Chicago Midway, runway 31C, 6,522 × 150 ft
Matched to the registry by N-number and the event date; the registry’s history has gaps, so older matches can be wrong. Compare the reported make and model.
Weather
- Conditions
- Visual (VMC) · Day
- Wind
- 180° at 4 knots
- Visibility
- 10 statute miles
- Lowest ceiling
- 20,000 ft broken
- Temperature
- 34 °F, dew point 25 °F
- Altimeter
- 30.26 inHg
- Observed at
- MDW
Docket · 9
The files NTSB released with the investigation on March 14, 2012, on NTSB’s docket system: statements, records, photos and specialists’ reports. 1.6 MB in all.