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 aircraft accident report.
While on a company visual flight rules flight plan, the instrument-rated commercial pilot and observer were returning from a three day pipeline patrol trip. On the morning of the accident they had "picked up" the pipeline and were following it on a 693-nautical mile cross-country flight to their home base. Standard procedure was to fly above the pipeline at an altitude of approximately 500-feet while the observer examined the pipeline. As they approached an airport for a planned fuel stop, the single-engine airplane impacted trees near the top of a hill that was located approximately 1.45 miles northeast from the approach end, and near the extended center line of the runway. The airplane came to rest in an inverted position about 275-feet beyond the initial tree impact. At the time of their arrival, the automated weather observation facility at the airport was reporting a visibility of 5 statute miles with 300-foot overcast. The wreckage was not located until about 1230 the following day. The airplane was equipped with an emergency locating transmitter; however, the transmitter was found in the "OFF" position. All major components of the airplane were accounted for at the site and there was no evidence of fire. An examination of the airframe and engine did not reveal any pre impact anomalies that would have prevented normal operation.