Incident Overview
A public use flight carrying four United States Forest Service (USFS) employees to a remote back-country airstrip experienced a delay of 2 hours due to heavy rain showers and a thunderstorm before departure. The planned route followed a highway through a river valley with high terrain—peaks exceeding 8,000 feet on both sides—until the highway diverged from the river, at which point the flight would continue along the river.
Weather Conditions
Available weather data indicated that as the airplane proceeded along the river valley, ridge tops on both sides became obscured. The overcast base was probably about 7,000 feet mean sea level, with ragged clouds and mist beneath due to recent rain showers. Slant visibility was likely diminished. Local pilots reported that under such conditions, the numerous drainages feeding into the river valley can appear similar.
Flight Progress and Radio Calls
Approximately 15 minutes after takeoff, the pilot made a position call stating he was over a small town near the point where the flight was to leave the highway. This was the last radio communication received from the airplane. However, analysis of radar data from the first 8 minutes of flight revealed the airplane was not at the reported position but well short of it.
Accident Sequence
About 15 minutes after the position call, witnesses heard and observed the airplane flying up a drainage short of the reported position. That drainage ended in a box canyon. Inspection of the accident site indicated the airplane was in a left climbing turn when it impacted steep terrain near the head of the drainage at an elevation of approximately 6,600 feet. The airplane nosed over, came to rest inverted, and a fire erupted.
Survivors and Aftermath
Three of the four occupants exited the burning wreckage. All communications equipment, survival equipment, and foul-weather gear aboard were destroyed in the fire. One of the three initial survivors succumbed to his injuries the following morning. The remaining two survivors then decided to depart the site for lower elevation due to extreme cold and precipitation. Searchers found the wreckage later that afternoon, and the two survivors walked out to the highway 2 days after the accident.
Aircraft and Pilot Examination
No abnormalities were noted during examination of the airplane that would have prevented normal operation. When the pilot took a check ride to qualify as pilot in command for public use flights carrying passengers into back-country, he reported to the check pilot that he had 100 hours of flight time in "typical terrain (over mountains)." USFS standards required 200 hours in typical terrain, but the standards did not define "typical terrain." Examination of the pilot's logbook revealed no specific record of back country or mountain flying experience. Review of entries over the past 2 years showed only 15 entries (14 hours of flight time) that included a takeoff or landing at a back-country airport.