19980829022389A

Acft was involved in an air show and declared and emerg during fly by, acft became caught in a strong downdraft and struck the ground. (.4) the aircraft was part of a flight of two aircraft conducting for-hire sightseeing flights from the airport. After the aircraft turned on to the crosswind leg, downdrafts were encountered by both aircraft. The accident aircraft made a turn to the left and the trailing aircraft turned to the right. The accident aircraft recovered close to the ground, collided with a telephone pole, and came to rest inverted. The aircraft was destroyed by a postimpact fire. The pilot of the aircraft stated that there were no mechanical anomalies experienced with the aircraft. The aircraft was at full power, but not gaining altitude. A witness to the accident reported that approximately 5 miles southeast of the airport were rain showers. The aircraft was examined and control continuity was established. No mechanical anomalies were noted. This was the sixth flight of the day, with no discrepancies noted with the previous flights. At the time of the accident the weather was deteriorating. Meteorological data showed the presence of instability and convectiv e activity conducive to up and downdrafts near the accident site. (-23) on August 29, 1998, at 1315 PDT, a Boeing A75N1, N56856, departed bigbear city airport (L35), on a commercial flight, carrying one passenger. The intent of the flight was an air tour of the Big Bear lake vicinity. The aircraft had flown 5 previous flights utilizing both runways 08/26. Winds throughout the day were light and variable although some convective activity was noticed approximately 10 miles south-east of the airport. N56856 took off on runway 08 following a sister ship. Both aircraft turned a right crosswind, and at approximately 700 feet AGL, they both encountered a severe downdraft. The lead aircraft turned onto a right downwind and recovered from the downdraft at approximately 100 feet AGL. N56856 turned left and remained in the downdraft which subsequently resulted in the aircraft contacting power lines, rolling over on its back and contacting the ground. The engine was producing full power throughout the incident.