Mammoth Yosemite Airport
Aircraft Accident/Incident Report

Mammoth Lakes, California 93546
Saturday, July 21, 2001 12:30 PDT

The pilot stated that while en route from Van Nuys to Mammoth Yosemite (MMH) via the Friant VOR radial 023, he entered a canyon and later realized that he had entered the wrong one. He said that the canyon was closed and above his altitude. He also stated that he was experiencing moderate turbulence from the time he entered the canyon up to the accident. The pilot began a "full power climb" at 75 knots in an attempt to clear the ridgeline at the end of the canyon. When he realized that he would not clear the terrain, he began a steep left turn. During the turn, the stall warning was activated and the pilot lowered the nose and shallowed the bank angle. He stated that the airplane struck trees on the top of the canyon edge, tearing off the left wing with the airplane striking the ground in a level attitude. He stated that, "The engine was working properly and all the gauges were in the green." According to the San Francisco sectional chart, the Mammoth Pool Reservoir, which is 55 nautical miles southwest of the MMH airport on a magnetic bearing of 213 degrees, is directly under the 023-degree radial of the Friant VOR. The pilot stated that when he saw the reservoir, he turned east toward the MMH airport. The magnetic course from the reservoir to the MMH airport was 033 degrees, or a northeasterly direction. There was a canyon leading northeast from the Mammoth Pool Reservoir along the Friant 023-degree radial, which is also Victor 230. The canyon terminated at Mammoth Lakes, which is 11 miles due west of the MMH airport. Had the pilot followed Victor 230 until reaching the Mammoth Pools, then turned to an easterly heading, he would have been proceeding directly to the airport.

The pilot's inadequate in-flight planning and his failure to maintain sufficient altitude above the terrain. Factors were the high terrain and the blind canyon.