Accident Sequence
A pilot conducting aerial defoliation of a cotton field reported that he was making alternating east-west spray passes from the south side to the north. An oil pumping rig was situated approximately 8 to 10 passes into the field. On each pass leading up to the rig, the pilot observed that the rig was not pumping and remained stationary on its down stroke.
As the aircraft performed a pass along the north edge of the pumping rig in a westerly direction, the left wing obstructed the pilot's view of the obstacle. The left wing subsequently struck the horse head of the pumping rig while it was on its upstroke, severing the outboard 6 to 8 feet of the wing.
Aftermath
After the impact, the pilot reduced the throttle to idle and allowed the aircraft to descend into the cotton field, where it came to rest inverted.
On-Site Observations
Oil company personnel at the scene reported that oil pumping rigs are common in the area. They further noted that the particular pumping unit involved was equipped with a timer and would shut off periodically.