Accident Summary
A Civil Air Patrol (CAP) aircraft, conducting a search and rescue training exercise (SAREX), collided with mountainous terrain after encountering mountain wave conditions and downdrafts. The two-man aircrew had flown from a mountain valley airport along the accident route earlier that day. The CAP group had been informed that high winds were expected the following day and flying operations might be cancelled. The aircrew decided to return to their home base in a small mountain town (elevation 6,748 feet) instead of staying at the SAREX base for the night.
Flight Details
The aircrew departed the SAREX base at night, and there was no moon illumination as they approached an 8,000–9,000 foot mountain ridgeline. The airplane approached the mountains at 10,300 feet and shortly thereafter entered a mountain wave, experiencing turbulence and downdrafts. Radar data showed that the airplane steadily descended through 8,000 feet during the last 4 minutes of the flight. The airplane impacted the side of the mountain at 6,970 feet elevation with low energy, in a very steep left turn with the left wing down.
Weather Conditions
Analysis of the weather conditions established that mountain wave conditions existed at 9,000 feet with a wavelength of 2.79 miles, amplitude of 717 feet, and a maximum vertical velocity of 1,185 feet per minute. This wave had the potential for moderate to severe turbulence. The aircrew had commented to the CAP Incident Commander that they experienced moderate turbulence on the earlier flight out of the mountains, severe enough to have their heads hit the cockpit canopy and toss a cell phone from the passenger's shirt pocket.
Additional Information
There is no record that the pilot requested or received a weather briefing. At the cruise altitude, the aircraft's performance charts indicate a maximum climb capability of about 400 feet per minute. The encounter with downdrafts in the 500 to 1,000 foot-per-minute range exceeded the aircraft's climb capability.