What happened
Three Piper J3 Cubs departed from an airport located in a valley characterized by nearby higher terrain and a density altitude of approximately 3,000 feet. The flight path for each aircraft involved a turn toward rising terrain composed of canyons, lower finger ridges, and a higher main ridge.
The first aircraft, operated by a pilot alone, successfully climbed above the terrain and turned downwind. The second and third aircraft, each carrying a pilot and a passenger, attempted to follow similar flight paths.
The pilot of the third aircraft observed the second aircraft descend into trees. After flying over the position of the second aircraft, the pilot of the third aircraft encountered descending air that forced the plane into the trees. The pilot of the third aircraft reported no mechanical or engine issues during the flight.
Findings
Investigation findings revealed that although the pilots had been briefed on alternate departure routes that would have avoided an immediate climb over rising terrain, those routes were not utilized. Additionally, FAA publications recommend reducing weight when operating at higher density altitudes and approaching ridgelines at a 45-degree angle to provide an escape path in the event of turbulence or descending air. The third aircraft was operated approximately 100 pounds, or 9%, over its gross weight.