Accident Overview
During an instrument approach in instrument meteorological conditions (IMC), a pilot flying a single-engine airplane misinterpreted the aircraft's position, leading to a controlled flight into terrain. The accident occurred after the pilot made two attempts at a VOR approach to an airport. The second approach ended with the airplane impacting rising terrain approximately 6.5 miles beyond the airport.
Flight Sequence
The airport's published instrument approach procedures included a VOR approach and a GPS approach. The VOR approach required the pilot to fly inbound to the VOR, then after passage, descend along the same course to a missed approach point defined by distance (6 nautical miles beyond the VOR) and timing. The pilot first flew the approach to the missed approach point, initiated a missed approach, and requested another VOR approach from air traffic control. After receiving vectors, the pilot re-intercepted the approach course inbound to the VOR. The airplane passed over the VOR on course at about 100 feet above the minimum altitude. However, instead of descending as per the procedure, the airplane maintained that altitude until reaching the airport, then began a descent. It continued outbound along the approach course until it struck rising terrain about 6.5 miles beyond the airport.
Navigation Considerations
The aircraft did not have dedicated Distance Measuring Equipment (DME). Distance was determined using an IFR-approved GPS unit. This unit did not store historical waypoint selections, so investigators could not determine the exact waypoints the pilot had entered. It was noted that the pilot could have selected the airport as a "direct to" waypoint or entered flight plan waypoints. In the latter case, the unit would have sequenced from the VOR to the airport during the first approach. Unless the pilot reprogrammed the unit, the last waypoint entered would have remained at the airport, not the VOR. Investigators concluded that the pilot most likely mistook the airport position for the VOR position, displacing the start of the descent by 6 nautical miles. Additionally, after passing the VOR en route to the airport, the Horizontal Situation Indicator (HSI) would have indicated a change from "TO" to "FROM."
Investigation Findings
No medical anomalies were found with the pilot, and no mechanical anomalies were noted with the airplane. The probable cause of the accident was the pilot's misinterpretation of the airplane's position relative to the final approach fix, which resulted in the displacement of the descent profile by 6 nautical miles and the subsequent controlled flight into rising terrain. Contributing to the accident were the low clouds.