The NTSB today determined that the probable cause of a fatal Boeing 737-700 runway overrun at Chicago-Midway Airport was the pilot`s failure to use available reverse thrust in a timely manner to safely slow or stop the airplane after landing. 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` failure to provide its pilots with clear and consistent guidance and training regarding company policies and procedures related to arrival landing distance calculations; programming and design of its on board performance computer, which did not present critical assumption information despite inconsistent tailwind and reverse thrust assessment methods; plan to implement new autobrake procedures without a familiarization period; and failure to include a margin of safety in the arrival assessment to account for operational uncertainties.
Contributing to the accident was the pilot`s failure to divert to another airport given the reports that included poor braking action and a tailwind component greater than 5 knots.
Also, contributing to the severity of the accident was the absence of an engineering materials arresting system (EMAS), which was needed because of the limited runway safety area beyond the departure end of runway 31C. (NTSB)