NTSB Identification: LAX87DJA06.
The docket is stored on NTSB microfiche number 34819.
Accident occurred Wednesday, April 22, 1987 in MOKULEIA, HI
Probable Cause Approval Date: 10/07/1988
Aircraft: SCHWEIZER SGS2-33, registration: N11468
Injuries: 1 Serious,2 Minor.

DURING A LOCAL SIGHTSEEING FLT ALONG A RIDGE LINE, WHILE MANEUVERING AROUND A CLOUD BUILD-UP, THE ACFT ENTERED A WINDSHEAR THAT SUDDENLY NOSED THE ACFT OVER IN AN APRX 75 DEG VERTICAL DIVE. JUST PRIOR TO COLLIDING WITH TREES, THE PLT WAS ABLE TO REGAIN SOME CONTROL OF THE ACFT AND COLLIDED WITH THE TERRAIN IN AN APRX 45 DEG ATTITUDE. IN THESE MOUNTAINS A CATABATIC WIND OFTEN FLOWS DOWNSLOPE AS SOLAR HEAT IS RADIATED FROM THE TERRAIN, COOLING THE TERRAIN SURFACE. THE TRADE WINDS CROSS THE RIDGES OBLIQUELY RESULTING IN EDDIES THAT PRODUCE OFF RIDGE FLOW. WHEN THE EDDIES AND CATABATIC GUSTS COINCIDE, A WIND SHEAR CAN OCCUR.

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

WEATHER CONDITION..WINDSHEAR


Contributing Factors

OBJECT..TREE(S)


Contributing Factors

ALTITUDE..INADEQUATE

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