No fatalities

Agricultural Airplane Strikes Tree After Airspeed Decay While Avoiding Power Lines

Bronson, IA, United States

On August 10, 2011, a WEATHERLY 201C operated by Sioux Air Inc was involved in an aviation accident near Bronson, IA. No fatalities were reported. Investigators recorded the probable cause as: The pilot's failure to maintain clearance from terrain while maneuvering during an aerial application flight. This summary draws on records from NTSB; 4 related events involving the same aircraft type or operator are linked below.

SourcesNTSBPrimary reportUpdated 2026-08-03Data APIEditorial standards

A pilot reported that while maneuvering to avoid high tension power lines during an agricultural application pass, airspeed decayed. After leveling wings and applying full power, the airplane entered a valley, sank, and struck a tree, resulting in substantial damage.

Accident Sequence

According to the pilot's report, the accident occurred during an agricultural application flight. While maneuvering to avoid high tension power lines, the airplane's airspeed decayed. The pilot leveled the wings and applied full engine power. In an effort to avoid a populated area, the pilot turned toward a low point in the rising terrain.

After exiting the agricultural field, the airplane entered a valley located between rolling hills. At that point, the airplane started to sink. The pilot observed a tree that was going to be a conflict and attempted to dump the chemical load. The airplane's right wing struck the tree, and the airplane subsequently impacted the ground.

Damage

The airplane sustained substantial damage to the right wing and fuselage.

Pilot's Report

The pilot reported that there were no failures or malfunctions associated with the airplane prior to the accident.

Contributing factors

Altitude — Not attained/maintainedClimb rate — Not attained/maintainedPilot

Frequently asked questions

What happened in the 10 Aug 2011 WEATHERLY 201C accident near Bronson, IA?

A pilot reported that while maneuvering to avoid high tension power lines during an agricultural application pass, airspeed decayed. After leveling wings and applying full power, the airplane entered a valley, sank, and struck a tree, resulting in substantial damage.

Were there any fatalities in the 10 Aug 2011 WEATHERLY 201C accident?

No fatalities were recorded in this accident.

What aircraft was involved and where did it happen?

The accident on 10 Aug 2011 involved a WEATHERLY 201C, operated by Sioux Air Inc, at Bronson, IA.

What was the probable cause of the accident?

The pilot's failure to maintain clearance from terrain while maneuvering during an aerial application flight.