NTSB Identification: LAX00LA035.
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Nonscheduled 14 CFR
Accident occurred Friday, November 12, 1999 in VAN NUYS, CA
Probable Cause Approval Date: 08/16/2001
Aircraft: American General Aircraft AG5B, registration: N1195L
Injuries: 3 Uninjured.
NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.
The outboard 1/3 of the aircraft's left wing was deformed upward about 5 degrees with respect to the inboard section during an encounter with wake turbulence while on downwind leg for landing. The upper wing skins of both wings exhibited compression buckling, and the mass balance weights on both ailerons were separated and fell from the aircraft. The pilot reported that the flight was unremarkable until, while downwind for landing, there was an instantaneous jolt of sudden severe turbulence that ended before he could take any action. Data obtained from the airport noise abatement office showed that 2 minutes 23 seconds prior to the encounter, a heavy transport aircraft passed over the location on an ILS approach to another airport 6 miles away; the transport airplane was about 500 feet higher than the accident airplane as it crossed the location. The air traffic control tower at the airport where the accident occurred made a wake turbulence cautionary broadcast to all aircraft 30 seconds prior to when the accident aircraft first contacted the tower for landing. The cautionary broadcast was not repeated.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: The pilot's encounter with unknown and unanticipated wake turbulence from a heavy transport aircraft, which was landing at another airport. A factor in the accident was the tower controller's failure to repeat a previously broadcast wake turbulence cautionary advisory when the aircraft later checked in on tower frequency. Full narrative available
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