Accident Overview
The airplane collided with high-tension power lines in a mountainous area following a deviation from the GPS approach procedure during instrument conditions. The aircraft was equipped with a GPS navigation system featuring a moving map display.
Flight and Communication Errors
After departure, the TRACON sector controller initially believed the airplane was destined for another airport and issued a clearance accordingly. The pilot questioned the clearance, leading to a correction. Shortly thereafter, the pilot deviated from the cleared course for unknown reasons in the direction of the mistaken airport. The controller noticed and corrected the course. A second controller, who would later handle the flight, overheard the correction and inferred the pilot was confused.
Upon handoff, the second controller attempted to provide a helpful method for transitioning to the GPS approach, but these methods did not strictly follow FAA Order 7110.65. The clearance included an intercept angle with the final approach course greater than allowed. The airplane was on a modified downwind proceeding to the initial approach fix (IAF) when the controller cleared the pilot to turn toward an intermediate fix between the IAF and the final approach fix (FAF), intending it as a radar vector. The pilot questioned the clearance but then acknowledged, turning left toward the FAF, which was behind the airplane. The controller noticed the left turn directed the airplane toward high terrain and advised a right turn to the intermediate fix. After some confusion, the airplane stabilized on the approach course after passing the intermediate fix.
Approach and Terrain Collision
As the airplane passed the FAF, the controller instructed the pilot to contact the tower but provided the frequency for the wrong airport. The pilot questioned this, but the controller insisted the frequency was correct. The pilot then contacted the second airport's tower and was told he was on the wrong frequency. Nearly one minute elapsed between the pilot's acknowledgment of the erroneous frequency and his initial contact with the correct tower. During this time, the airplane's heading diverged approximately 90 degrees from the published final approach course toward rising terrain and the accident site.
The Minimum Safe Altitude Warning (MSAW) alarms activated in both the TRACON and the tower. The tower controller issued a low altitude safety alert by stating "check your altitude immediately." At that moment, the airplane was about 500 feet above the Minimum Descent Altitude (the accident site elevation was about 200 feet above the MDA). The alert was triggered not because the airplane's altitude was below segment minimums, but because its course and altitude projected impending terrain contact. This may have confused the pilot and reduced perceived urgency. The radar display limitations masked the initial course deviation; the controller did not see it for about 30 seconds but advised the pilot upon awareness. The pilot's unintelligible response occurred around the time the radar target entered coast mode.