On August 31, 1992, a Grumman 164A (registration N48635) operated by AG Aviation Services, Inc. was involved in an aviation accident near Elkhorn, WI. Investigators recorded the probable cause as: The pilot's decision to initiate a swath run with a crosswind to downwind turn toward a hillside with trees, which resulted in increased ground speed and downslope airflow contributing to the collision. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
An airplane engaged in aerial application collided with trees and terrain while executing a turn toward a hillside, citing increased ground speed and downslope airflow as contributing factors.
What happened
During an aerial application maneuver, the aircraft experienced a collision with trees and the terrain. The pilot stated that due to a local dairy operation, he found it necessary to initiate the swath run with a crosswind to downwind (tailwind) turn toward a hillside with trees. The pilot said that he suspected that the increased ground speed and downslope airflow contributed to the accident.
The investigation
The pilot provided a statement regarding the circumstances leading up to the collision, noting the operational necessity of adjusting the flight path due to nearby agricultural activities.
Probable cause
The pilot's decision to initiate a swath run with a crosswind to downwind turn toward a hillside with trees, which resulted in increased ground speed and downslope airflow contributing to the collision.