Accident Sequence
The pilot was performing a night, VFR traffic pattern to a full stop at a non-towered airport in a turboprop aircraft. He entered the traffic pattern (runway elevation 6,800 feet; pattern altitude 1,000 feet AGL) on an extended downwind leg. Radar data indicated that his groundspeed was 205 knots. Over the next 3 nautical miles on downwind, radar data showed he slowed to a groundspeed of 171 knots, lost approximately 500 feet of altitude, and reduced his parallel distance from the runway from 4,775 feet to 2,775 feet.
Witnesses observed a bright blue flash, followed by a loss of contact with the airplane. Two witnesses reported that his radio transmissions on CTAF appeared normal. Rescue personnel found a broken and downed static wire from a system of three sets of power transmission wires. The dark night precluded ground rescue personnel from locating the downed aircraft; a police helicopter found the airplane approximately 2 hours after the accident.
Pilot Background
The pilot had recently completed his factory-approved annual flight training. His flight instructor stated that the pilot was taught to fly a VFR traffic pattern at 1,500 feet AGL (or 500 feet above piston-powered aircraft), enter the downwind leg from a 45-degree leg, and fly parallel to the downwind approximately 1 to 1.5 nautical miles separation from it. His speed on downwind should have been 145 to 150 knots indicated, with 90 to 95 knots on final for a stabilized approach. The flight instructor noted that the base turn should be at a maximum bank angle of 30 degrees.
Radar Data
Radar data indicated that the pilot was in a maximum descent while turning base to final of 1,800 to 1,900 feet per minute with an airspeed on final of 145 to 150 knots. His maximum bank angle during this turn was calculated to have been more than 70 degrees.
Wreckage and Examination
The separated static wire was located 8,266.5 feet from the runway threshold, and was approximately 30 feet higher than the threshold. Post-accident examinations of the airplane and its engine revealed no anomalies which would have precluded normal operations prior to impact.