Incident Overview
An agricultural pilot was conducting aerial application operations over a rectangular field. According to the pilot, he had successfully completed six passes below transmission lines that ran diagonally above the field. The pilot had previous experience with the same field, having completed 11 or 12 similar application flights over previous years, including one earlier that month.
Events Leading to the Strike
As the pilot turned the airplane toward its seventh pass, the position of the sun and windshield spray residue caused him to briefly lose sight of the transmission lines. He subsequently regained sight of the lines and continued the pass; however, the airplane struck the lines during the pass. The impact damaged the wing spar.
Post-Incident Actions
After striking the transmission lines, the pilot returned to the originating airport. The pilot did not report any preexisting mechanical anomalies with the airplane.
Analysis
The incident involved a loss of visual contact with obstacles due to environmental factors. The pilot had successfully navigated the same area on multiple previous occasions, indicating that the specific conditions during the seventh pass were key to the event. No other contributing factors were identified by the pilot.