Schweizer Aircraft Corp G 164B N3627R accident near Tulelake, California

Probable cause

The pilot's failure to maintain clearance from power lines while maneuvering during low-altitude operations.

NTSB analysis

The pilot was applying the last load of insecticide to a field in the agricultural biplane when the top wing struck power lines as the biplane passed underneath it. The operator reported that the pilot had applied insecticide to the same field many times. Further, he had flown under the power lines many times without incident. There were no witnesses to the accident; a spotter who had been assigned to the pilot was transitioning to another location at the time.

Postaccident examination of the airframe and engine did not reveal any anomalies that would have precluded normal operation, and the propeller's damage signatures indicated that the engine was operating at the time of impact. At the time of the accident, the sun would have been positioned just off the airplane's right wing; therefore, it is unlikely that the sun hindered the pilot's view. The airplane struck thinner lines that were about 10 ft below 40-ft-high thicker lines; therefore, it is possible that the pilot was focused on the upper lines and did not see the lower ones.

Text from the NTSB. Open the NTSB docket for WPR14LA322 for the full record.