What happened
On July 19, 2013, an Air Tractor AT-802A operated by Milhon Air, Inc. was conducting an aerial application flight near the Huntingburg Airport (KHNB) in Indiana. The flight, which began at 0930, was flying on an easterly heading through a small valley.
While performing spraying maneuvers, the aircraft, registration N86BM, struck suspended power lines located at the eastern edge of the field being treated. Following the collision, the airplane impacted the terrain approximately 1.5 miles east of the airport. The aircraft continued toward a group of trees near a lake, where it eventually came to rest. The pilot sustained one serious injury and was not killed in the accident. The aircraft was destroyed.
The investigation
Federal Aviation Administration (FAA) inspectors examined the wreckage and the accident scene. They found that the power line poles were oriented north-south and that the impact had severed the line, leaving it on the ground in the direction of the accident.
Mechanical examination of the Air Tractor AT-802A showed no evidence of engine or flight control malfunctions that would have prevented normal operation. The engine had separated from the fuselage upon impact, and three of the four propeller blades were lost. The wings sustained damage, and the empennage separated from the fuselage.
Data recovered from the SatLoc M3 CPU, an on-board control system, provided a record of the flight path. The data showed that while the pilot performed scouting circles to look for obstructions over the first field, no such scouting passes were performed over the second or third fields. The final recorded data points indicated the pilot was flying at approximately 162 miles per certain altitude of 240 feet above the ground, appearing to set up for a spray run.
Findings
Investigators determined that the pilot was flying toward the sun during the final maneuver. Because the pilot did not perform scouting passes over the final field to identify potential hazards, the power lines were not identified before the collision.