NTSB Identification: DCA05MA083
Scheduled 14 CFR Part 121: Air Carrier
Accident occurred Monday, July 11, 2005 in Raleigh-Durham, NC
Probable Cause Approval Date: 04/30/2008
Aircraft: Boeing 767-232, registration: N113DA
Injuries: 1 Serious,186 Uninjured.
NTSB investigators traveled in support of this investigation and used data obtained from various sources to prepare this aircraft accident report.
The captain stated that after takeoff he waited until FL370, and well past the line of weather, to turn off the seat belt light. The flight was smooth for about 10 to 15 minutes, and they transited in and out of cirrus clouds, with the weather radar being used to scan from the 160 to 40 mile range, and with no weather being noted. As the flight progressed he said they encountered moderate turbulence for about 10 to 15 seconds, and he immediately made an announcement for the flight attendants and passengers to sit. Shortly thereafter the captain said he was informed that a flight attendant had been injured. The first officer stated that as the flight climbed they easily transited between two cells, entered clear skies, and was in smooth air. The seat belt sign had been turned off, and the captain continued searching the area with the weather radar. The first officer said that although there were some intermittent high cirrus clouds, there was no weather that would pose problems along the route of flight. About 10 to15 minutes after level-off, the first officer said the airplane hit what he would call severe turbulence, and both he and the captain were tossed about in their seats. They were initially unable to either grab the flight controls, or turn on the seat belt sign, and after the initial big bump, the first officer said "he grabbed the controls (it was my leg), and followed through with the thrust levers and yoke." According to the first officer, as soon as able the captain turned on the seat belt sign, made the announcement for everyone to sit down, and they soon heard a flight attendant make an announcement asking for a doctor. All flight attendants provided statements that were consistent, affirming that there had been turbulence, and that the seat belt sign was not lit during the turbulence prior to the accident. The NTSB conducted studies of airplane's DFDR, as well a study of the weather around the time of the accident. Examination of the DFDR revealed information affirming that the autopilot had been engaged, and consistent with there having been an encounter with turbulence. The weather study examined many weather products and provided data consistent with there being convectively induced turbulence in the vicinity of strong to severe thunderstorms.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: An inadvertent in-flight encounter with clear air turbulence. Full narrative available
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