Southwest Airlines Flight 1248


Southwest Airlines Flight 1248 was a scheduled passenger flight from Baltimore, Maryland, to Chicago, Illinois, to Salt Lake City, Utah, and then to Las Vegas, Nevada. On December 8, 2005, the airplane slid off a runway at Chicago-Midway while landing in a snowstorm and crashed into automobile traffic, killing a six-year-old boy.

Aircraft and crew

The aircraft, a one-year-old Boeing 737-700 with tail number was delivered to Southwest in July 2004. It was powered by two CFM International CFM56-7B24 turbofan engines.
The captain was 59-year-old Bruce Sutherland, who had been a former U.S. Air Force pilot. He joined Southwest Airlines in August 1995 and had 15,000 flight hours, including 4,500 hours on the Boeing 737. The first officer was 34-year-old Steven Oliver, who had been working for the Airline since February 2003, having previously served as a captain for Mesaba Airlines. The first officer had 8,500 flight hours, with 2,000 of them on the Boeing 737. Neither pilot had been involved in any accident or incident before Flight 1248.
Captain Sutherland was the pilot flying and first officer Oliver was the pilot monitoring.

Accident

On Thursday, December 8, 2005, Southwest Airlines Flight 1248 was scheduled to arrive at Chicago Midway International Airport from Baltimore-Washington International Thurgood Marshall Airport, and then continue on to Salt Lake City International Airport, then to Las Vegas McCarran International Airport. The flight circled over a small area in northwest Indiana several times before attempting to land in a snowstorm. The snowstorm had reduced visibility to less than one mile.
At around 7:15 PM CST, the pilot attempted a landing with nearly eight inches of snow on the ground in the area. Airport officials stated that the runway was cleared of snow prior to the time of landing. The latest reported weather had the wind from between east and east-southeast at.
A south easterly wind would normally favor landing into the wind on runway 13 Center. The runway visual range was reported at, below the landing minimums for the Instrument Landing System approach to runway 13C. The only available runway with lower minimums was the opposite direction on 31C, which the crew selected, with the aircraft's groundspeed consequentially boosted by the tailwind.
The 737 skidded during landing; subsequently, witnesses said the nosegear collapsed and the aircraft crashed into a barrier wall surrounding the airport, coming to rest on Central Avenue just south of the 55th Street intersection at the northwestern corner of the airport. The intersection was full of traffic, and the airplane hit at least three cars, killing a six-year-old boy, critically injuring five occupants of one car, and seriously injuring four occupants of a second car. All were quickly taken to area hospitals. Three passengers from the aircraft were taken to hospitals with minor injuries. All told, twelve people were taken to hospitals after the incident. One other car hit was parked and unoccupied.

Investigation

The National Transportation Safety Board investigated the accident. Chicago Fire Department Commissioner Cortez Trotter said the aircraft would not be removed from the intersection until the NTSB gave clearance to do so following its on-site investigation. The nose of the aircraft was hoisted onto a flatbed tractor-trailer on Saturday, December 10, and the 737 was towed to a hangar for continued inspection.
As the Boeing 737-700 is a "Next Generation" model, the aircraft was equipped with the latest anti-skid and braking technology. The report noted that Southwest had only very recently begun actually using the autobrake systems, and that pilot training on proper use of auto brakes had been inadequate.
The NTSB preliminary report determined that the aircraft touched down in the touchdown zone of the runway with of its length remaining; under the prevailing conditions of weather, wind, speed, and weight, the aircraft needed of runway to stop safely. It was found that the tailwind was 8 knots and exceeded the required limit of 5 knots.
A preliminary NTSB advisory says:

"The flying pilot stated that he could not get the reverse thrust levers out of the stowed position. The first officer, after several seconds, noticed that the thrust reversers were not deployed, and activated the reversers without a problem. Flight data recorder information reveals that the thrust reversers were not deployed until 18 seconds after touchdown, at which point there was only about of usable runway remaining."

Alternately, the crew could have held in the air, waiting for the weather to improve, or they could have diverted to another airport, such as Chicago O'Hare International, whose substantially longer runways were 10 minutes' flying time away. Each of these options would have entailed considerable additional expense for Southwest, as well as missed connections and significant inconvenience for the flight's passengers. The National Transportation Safety Board identified the psychological pressure to complete their assigned task as one of the factors contributing to the crew's decision to land at Midway despite unfavorable conditions. Cockpit voice-recorder transcripts indicate the pilots had been concerned about the weather and, prior to landing, jokingly alluded to the movie Airplane!, saying, "I picked a bad day to stop sniffin' glue."
The NTSB discovered that the air traffic controller told the pilots that the braking action for the first half of the runway was good and poor for the second half. However investigators found that the controller didn’t give the pilots all the required braking action reports available because he didn’t take into account the aircraft type from which the reports came from. One of these planes was a small plane that reported poor braking conditions. It was found that braking action reports varied significantly based on aircraft type, changing weather conditions, personnel experience, the type of equipment used, and the time of report, and therefore shouldn’t be used as conclusive information on runway conditions.
The pilots stated that based on the calculations they made into the Onboard Performance computer, they believed they could land and stop safely. However investigators determined that the OPC based its stopping margins on 2 assumptions: first that the tailwind is lower than that during the accident and second that the thrust reversers are deployed on time upon landing. It was found that the pilots were unaware of these assumptions and that Southwest hadn’t provided sufficient recurrent training on them. So therefore the pilots didn’t use the critical braking action term “poor” when assessing the landing performance.
Southwest Airlines had a policy that required pilots to consider more critical braking action assessments when they receive mixed braking action reports. However it was found that the accident pilots were unaware of this policy and therefore didn’t consider it while assessing landing conditions. The NTSB also found that 3 other company pilots landed before the accident with the same mixed braking action reports. When interviewed company pilots revealed that they too either didn’t adhere to the mixed braking policy or weren’t aware of it. Southwest also hadn’t routinely trained its pilots on following or understanding the mixed braking action report policy, and it wasn’t referenced in the company manuals.
The NTSB concluded that even under the poor braking conditions and the tailwind, the plane could have stopped in time had the pilots deployed the thrust reversers on time. Examination of the reverser system found no evidence of malfunction.
The National Transportation Safety Board determined that the probable cause of this accident was the pilots’ failure to use available reverse thrust in a timely manner to safely slow or stop the airplane after landing, which resulted in a runway overrun. This failure occurred because the pilots’ first experience and lack of familiarity with the airplane’s autobrake system distracted them from thrust reverser usage during the challenging landing.
Contributing to the accident were Southwest Airlines’ 1) failure to provide its pilots with clear and consistent guidance and training regarding company policies and procedures related to arrival landing distance calculations; 2) programming and design of its on board performance computer, which did not present critical assumption information despite inconsistent tailwind and reverse thrust assessment methods; 3) plan to implement new autobrake procedures without a familiarization period; and 4) failure to include a margin of safety in the arrival assessment to account for operational uncertainties. Contributing to the severity of the accident was the absence of an engineered materials arrestor system, which was needed because of the limited runway safety area beyond the departure end of runway 31C."

Aftermath

It is now recommended practice for any new runway to have a clear area at least long at each end, called a 'runway safety area', to allow additional space for an aircraft that overruns the runway to decelerate and stop in relative safety. As Midway was constructed before these rules were put in place, it does not have this safety area. The accident renewed debates on the need for, and feasibility of, an engineered materials arrestor system, or EMAS, at Chicago Midway, given the lack of adequate overrun areas, and the surrounding residential neighborhoods. Additionally, actions taken by the city to acquire land for a buffer zone around the airport came to light after the crash. In 2007, installation began on modified, short-length arrestor beds. The first one was completed at the end of Runway 31C by summer 2007. EMAS beds have also been installed at the end of 04R, 13C and 22L.
The accident occurred 33 years to the day after United Airlines Flight 553, also a Boeing 737, crashed while approaching Midway Airport, killing 45.
The accident involving Flight 1248 was the first Southwest Airlines accident in the 35-year history of the company to result in a fatality. The previous major incident was in 2000 when Southwest Airlines Flight 1455 overran a runway in Burbank, California, injuring 43 and narrowly avoiding a catastrophe; the aircraft ended up outside a Chevron gas station.
As a direct result of the accident, the U.S. Federal Aviation Administration created a Takeoff and Landing Performance Assessment Aviation Rule-making Committee.. In 2016, based on the recommendations of TALPA ARC, the FAA implemented new "Runway Condition Code" method for the communication of runway conditions from airport management to flight crew members.
Although the Midway accident killed a person on the ground rather than a passenger or crew member, Southwest followed the tradition of retiring any flight number involved in a fatal crash; current flights from Baltimore to Chicago departing at or around 3:55 PM were designated Flight 1885 until that flight number was moved to a different flight. Southwest also petitioned the FAA in July 2006 to have the tail number of the aircraft changed to N286WN. After a lengthy repair, the aircraft emerged from Southwest's Midway hangar as N286WN in September 2006.

Events at Midway