National Transportation Safety Board
Office of Public Affairs
Washington, DC - The National Transportation Safety Board has determined that the incident last year involving an uncommanded pitch-up aboard an aircraft occurred as a result of the inadvertent partial inflation of the evacuation slide and subsequent binding of the elevator control cables. Contributing to this incident was the evacuation slide cover failing to be secured to the floor fittings on the walkway.
At 8:45 a.m. (CDT) on July 7, 2008, a McDonnell Douglas MD- 81, carrying then Senator Barack Obama, experienced a tailcone evacuation slide inflation shortly after takeoff. The aircraft was operated by Midwest Airlines as Flight #8663 and took off from Chicago, Illinois for Charlotte, North Carolina. According to post-incident flight crew statements, during the initial climb, the airplane's pitch increased without a corresponding flight control input and exceeded normal limits before the captain was able to regain control. Once under control, the airplane was diverted to Lambert-St. Louis International Airport and made an uneventful landing at about 9:00 a.m. (CDT). None of the 2 flight crewmembers, 4 flight attendants, 2 airline representatives, or 43 passengers were injured.
Post-incident inspection of the airplane indicated that the tailcone evacuation slide had inflated inside the tail area of the airplane as it had lifted off; this resulted in the reported pitch control restriction. The airplane received minor damage to the evacuation slide, the walkway, and a set of elevator cables in the tailcone.
Shortly after the incident, the carrier released a maintenance alert bulletin describing the incident and initial investigation findings, as well as a revision to the service check agenda, which added specific instructions for maintenance personnel for verifying proper slide installation. Additionally, the aircraft manufacturer has agreed to publish a Fleet Digest article on the incident to notify other carriers of the findings.
The probable cause report is available on the NTSB's website.
NTSB Office of Public Affairs: (202) 314-6100
The National Transportation Safety Board (NTSB) is an independent federal agency charged with determining the probable cause
of transportation accidents, promoting transportation safety, and assisting victims of transportation accidents and their families.