Investigation Summary
The accident occurred during a period of heavy snowfall and deteriorating runway conditions. The flight crew used an On-Board Performance Computer (OPC) to calculate landing performance, but they were unaware that the software automatically included 'credit' for thrust reversers in its calculations. If this credit had been excluded, the OPC would have indicated a landing was not possible. Upon touchdown, the Captain struggled to deploy the thrust reversers. This difficulty was linked to the crew's lack of familiarity with the autobrake system, which Southwest Airlines had only recently implemented fleet-wide without a formal familiarization period. The First Officer eventually intervened, but the reversers were not deployed until 18 seconds after touchdown, leaving only 1,000 feet of runway remaining. The aircraft exited the airport perimeter at approximately 40 mph, crossing into the intersection of West 55th Street and South Central Avenue.
Final Conclusions
The NTSB determined the probable cause was the pilots' failure to use available reverse thrust in a timely manner to safely slow or stop the airplane. This was attributed to a lack of familiarity with the autobrake system which distracted the crew during a challenging landing. Contributing factors included Southwest Airlines' failure to provide clear guidance on landing distance calculations, the design of the OPC which hid critical assumptions from the pilots, and the implementation of new procedures without a proper familiarization period. The NTSB also cited the pilots' failure to divert to another airport, such as O'Hare, despite reports of poor braking action and a tailwind exceeding 5 knots. The lack of an Engineered Materials Arrestor System (EMAS) at the end of the runway contributed to the severity of the outcome.
Photographic Evidence (1)
Video Analysis
Disregarded Guidelines | Southwest Airlines Flight 1248 — A detailed look at the 2005 Midway runway overrun, exploring the pilot errors, software assumptions, and the tragic ground fatality.
If playback is blocked, the owner has disabled embedding — use the link above.
Crew Experience
Captain
Bruce Sutherland, former U.S. Air Force pilot. Pilot Flying (PF).
First Officer
Steven Oliver, former Mesaba Airlines captain (4,000 hours as captain). Pilot Monitoring (PM).
Systems & Failure Modes
On-Board Performance Computer (OPC)
A laptop-based tool used by pilots to calculate landing distances; it assumed thrust reverser deployment without explicitly informing the crew.
Autobrake System
A system that automatically applies wheel brakes upon landing; the crew's lack of experience with this system caused distraction during the rollout.
Engineered Materials Arrestor System (EMAS)
A bed of crushable concrete designed to stop overrunning aircraft; its absence at Midway was cited as a factor in the accident's severity.
Interesting Facts
- 01The aircraft was a Boeing 737-700 delivered new to Southwest in 2004.
- 02The tailwind at the time of landing was 8 knots, exceeding the 5-knot limit for the reported runway conditions.
- 03The fatality was a six year old boy who was a passenger in a car struck by the aircraft.
- 04This was the first fatal accident in Southwest Airlines' 35-year history.
- 05The aircraft was repaired and returned to service under a new registration, N286WN.
- 06Following the accident, Southwest Airlines retired flight number 1248, a standard industry practice.
Safety Actions & Advisories
EMAS Installation
Source ↗Following the accident, the City of Chicago installed Engineered Materials Arrestor Systems (EMAS) at the ends of several runways at Midway, including 31C.
TALPA ARC Formation
Source ↗The FAA created the Takeoff and Landing Performance Assessment Aviation Rulemaking Committee to improve runway condition reporting.
Runway Condition Codes
Source ↗In 2016, the FAA implemented a new numerical Runway Condition Code system to standardize communication between airport management and flight crews.