Cessna 172 N284SP accident near Indiantown, Florida

Probable cause

The pilot's failure to maintain an adequate airspeed while maneuvering at low altitude. Contributing to the accident was the overweight condition of the airplane and the inoperative stall warning horn.

NTSB analysis

The purpose of the flight was to conduct aerial surveys of bird activity. During a circling pass, at an altitude about 300 feet above ground level (agl), a witness observed the nose of the airplane drop. The airplane then banked to the right with an accompanying increase in engine noise, and descended into the ground. The airplane had flown approximately 1.5 hours since being serviced with fuel on the morning of the accident flight. The airplane was 5 pounds over maximum gross weight based on the measured weight of the contents. Fuel was observed in the surrounding areas of the accident site, and as such, the maximum gross weight was considered higher than the measured value. Impact damage on the nose, wings, and fuselage were consistent with a stall/spin and subsequent collision with terrain. Postaccident examination revealed that the stall warning device was inoperative at the time of the accident. Two pilots who had previously flown the bird surveying missions, reported that they were instructed by the research leader to fly the airplane at altitudes between 200 and 500 feet agl. They further reported that the type of maneuvers and low airspeeds required to perform the missions would often cause the stall warning horn to sound. Aside from the stall warning horn, no other preimpact mechanical malfunctions were identified with the accident airplane.

Text from the NTSB. Open the NTSB docket for NYC08FA133 for the full record.