NTSB Factual Report

HISTORY OF FLIGHT

On October 10, 1997, about 1700 hours Pacific daylight time, a Schweizer 2-32, N242DB, operated by Sky Sailing Airport, was substantially damaged during a passenger flight near Warner Springs, California. The pilot sustained fatal injuries, one passenger received serious injuries, and the second passenger received minor injuries. The sailplane departed Warner Springs about 1625 by an airplane tow to a point near Ranchita, California, where it was released at 8,000 feet msl. The sailplane was to remain aloft for a 40-minute scenic flight. Visual meteorological conditions were reported at the time of departure.

The sailplane failed to return to Warner Springs during the allotted time and a search was initiated. It was located the next day on Hot Springs Mountain in the Los Coyotes Indian Reservation.

According to the passenger statement, they reached an altitude of 14,000 feel msl. They stated at the end of the flight the pilot descended through the clouds. They collided with mountainous terrain about 6,000 feel msl.

PILOT INFORMATION

The certificated commercial glider pilot had accumulated about 6,636 total glider flight hours. The pilot had flown three previous flights on the day of the accident for a total flight time of 1:20 minutes.

AIRPLANE INFORMATION

Examination of the aircraft logbook revealed that the last annual inspection occurred on November 28, 1996. Excerpts from the log are included in this report.

METEOROLOGICAL INFORMATION

The closest official weather reporting facility was located at NAS Miramar. At 1655, it was reporting: winds 250 degrees at 17 knots with gusts to 25 knots; 7 miles visibility; few clouds at 6,000 feet agl; few clouds at 20,000 feet agl; temperature 80 degrees Fahrenheit; dew point 52 degrees Fahrenheit; altimeter 29.70 inHg.

An ocean/atmosphere scientist glider pilot, who was flying the same area near the accident time, stated that the day was dominated by powerful yet rapidly changing lee wave systems producing 10/20 knot updrafts and downdrafts in the coastal mountain ranges of the lower Southern California Bight. Based on 1,800 hours of flying the wave, this unusual day was a 1 in 1,000 occurrence, changing minute by minute. He also stated that the lee wave structure is normally very steady and reliable.

The glider pilot's day of soaring started at 1140 and ended back at Warner Springs at 1713. He reported that a complex arrangement of stable and weakly stable layers existed below 16,000 feet, with a deep unstable surface layer which produced upslope convection late in the day with cloud bases at 5,000 feet msl and cloud tops at 9,500 feet. The associated upslope convection obscured all local mountain slopes above 5,000 feet after 1530. The Warner Springs and San Felipe valleys were open with 3/10's scattered cloud coverage.

The first encounter that day occurred about 1255 with disintegration of a non-hydrostatic wave and reformation as a hydrostatic wave with plunging flow. This encounter resulted in a loss of 10,000 feet (from 18,000 to 8,000 feet). On three separate occasions he encountered abrupt disintegration of a well ordered non-hydrostatic wave which resulted in the immediate loss of as much as 7,000 to 10,000 feet of altitude.

WRECKAGE AND IMPACT INFORMATION

On-scene examination of the aircraft revealed that it had collided with natural growth pine trees about 6,000 feet msl on Hot Springs Mountain. The aircraft was commingled with tree structures and was substantially damaged but intact. According to the aircraft compass, the direction at rest was 190 degrees magnetic.

MEDICAL AND PATHOLOGICAL INFORMATION

On October 12, 1997, the San Diego County Medical Examiner performed an autopsy on the pilot. The cause of death was attributed to multiple blunt force trauma. During the examination samples were obtained for toxicological examination by the Federal Aviation Administration Civil Aeromedical Institute in Oklahoma City, Oklahoma. The results of the analysis were negative for all screened drugs and ethanol.

ADDITIONAL INFORMATION

The on-board camera was recovered closed with minor damage at the bottom mounting point. The camera was taken to a photo processor who reported that the camera had been opened and half of the film was ripped out of the camera. There were 10 pictures recovered, of which 4 were light damaged.

The Safety Board did not take possession of the wreckage.

NTSB Probable Cause

the pilot's inadvertent flight into instrument meteorological conditions after inadvertently encountering mountain wave and associated downdraft conditions. The obscuration and high/mountainous terrain were related factors.