NTSB Identification: SEA04GA192.
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Accident occurred Monday, September 20, 2004 in Essex, MT
Probable Cause Approval Date: 09/13/2005
Aircraft: Cessna U206G, registration: N206SM
Injuries: 3 Fatal,2 Serious.

: NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this public aircraft accident report.

The purpose of the public use flight was to transport four United States Forest Service (USFS) employees to a remote back-country airstrip. The flight's departure was delayed 2 hours due to heavy rain showers and a thunderstorm. The planned flight route was to follow a highway through a river valley with high terrain (peaks above 8,000 feet) on both sides until reaching a point where the highway diverged from the river. At that point, the flight was to leave the highway and follow the river. Analysis of available weather data indicated that as the airplane proceeded along the river valley, ridge tops on both sides of the valley became obscured. Bases of the overcast were probably about 7,000 feet msl. Ragged clouds and mist were probably present beneath the overcast due to recent rain showers in the area. Slant visibility was likely diminished. Local pilots reported that in these type weather conditions the numerous drainages that feed into the river valley can be similar in appearance. The pilot made a position call about 15 minutes after takeoff stating that he was over a small town located close to the point where the flight was to leave the highway. This was the last radio communication received from the airplane. Analysis of radar data available for the first 8 minutes of the flight indicated the airplane was not at the position reported by the pilot, but was actually well short of this position. About 15 minutes later, witnesses heard and saw the airplane flying up a drainage located short of the reported position. This drainage ended in a box canyon. Inspection of the accident site indicated that the airplane was in a left climbing turn when it impacted steep terrain near the head of the drainage at an elevation of about 6,600 feet. The airplane nosed over, came to rest inverted, and a fire erupted. Three of the occupants exited the burning wreckage. All communications equipment, survival equipment and foul-weather gear aboard the airplane were destroyed in the fire. One of the three initial survivors died from his injuries the following morning. At that time, the remaining two survivors decided to depart the site for lower elevation due to extreme cold and precipitation. Searchers found the wreckage later that afternoon. The two survivors walked out to the highway 2 days after the accident. No abnormalities were noted during examination of the airplane that would have prevented normal operation. When the pilot took a check ride that allowed him to act as pilot in command of public use flights carrying passengers into the back-country, he reported to the check pilot that he had 100 hours flight time in "typical terrain (over mountains)." USFS standards required 200 hours flight time in typical terrain. However, the standards did not define typical terrain. Examination of the pilot's logbook revealed that it did not include a specific record of back country or mountain flying experience. Review of the past 2 years of logbook entries revealed a total of only 15 entries (14 hours flight time) that included a takeoff or landing at a back-country airport.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

The pilot's misidentification of the airplane's location, which resulted in his improper decision to fly into the wrong drainage, and his failure to maintain terrain clearance while executing a turn to reverse course after he realized his navigational error. Contributing factors were the low visibility due to mist, obscuration of the mountainous terrain, and the pilot's lack of experience in back country flying.

Full narrative available

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