NTSB Identification: DCA08FA062
Nonscheduled 14 CFR Part 121: Air Carrier operation of Omni Air International
Accident occurred Monday, May 19, 2008 in
Probable Cause Approval Date: 06/24/2009
Aircraft: MCDONNELL DOUGLAS DC10, registration: N720AX
Injuries: 1 Serious,4 Minor,157 Uninjured.

NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this aircraft accident report.

The captain stated that the ride had been smooth at their cruise altitude of 36,000 feet, and the seatbelt sign was off. He further stated that there was some thunderstorm activity, and some towering cumulus in the area, and that the airplane’s radar indicated the presence of a cell about 30 miles south of the airplane’s position, with tops that reached about 28,000 to 30,000 feet. He said they encountered an area of higher clouds, but the radar still did not indicate any activity, and within a few seconds they felt an initial bump, followed by "moderate" turbulence. He said he then turned the seatbelt sign on, and a short while later he was notified that there were some injured passengers and flight attendants. The NTSB’s Recorder Laboratory, Washington DC, read out the DFDR, and the data indicated that at 13:27:22 FDR Recorded GMT, at a pressure altitude of 36,000 feet, the vertical acceleration changed from 0.9 g’s to 1.8 g’s to -0.5 g’s to 1.7 g’s and then back to 0.9 g’s all within 3 seconds, consistent with clear air turbulence. See the NTSB DFDR Factual Report. In addition the NTSB conducted a meteorological study, using data to include synoptic, upper air, and satellite data. See the NTSB Meteorological Factual Report.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

An inadvertent in-flight encounter with unforecasted clear air turbulence

Full narrative available

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