Cessna 172 N612DF accident near Danbury, Connecticut

Probable cause

The pilot's exceedance of the airplane's critical angle of attack during initial climb, which resulted in an aerodynamic stall. Contributing to the accident was the pilot's decision to operate the airplane above its maximum gross weight, which likely reduced its takeoff performance.

NTSB analysis

The private pilot and two passengers were departing in the airplane from the 4,422-ft-long asphalt runway. A witness reported that, while still over the runway, the airplane began to lose altitude, then entered a nose-high attitude. The airplane subsequently entered a left-turning descent consistent with an aerodynamic stall. Examination of the wreckage did not reveal any preimpact mechanical anomalies; although the ignition key was found in the left magneto position, the preimpact position of the key could not be determined.

Performance calculations revealed that the airplane should have used less than half the available runway distance to clear a 50-ft obstacle at maximum gross weight with flaps extended to 10°. Weight and balance calculations revealed that the airplane was operating about 59 lbs over its maximum allowable gross weight at the time of the accident, and the flaps were found in the retracted position. It is likely that the pilot noticed the airplane's degraded climb performance after takeoff and attempted to compensate by increasing the airplane's pitch attitude, which resulted in decaying airspeed, an exceedance of the critical angle of attack, and an aerodynamic stall.

Text from the NTSB. Open the NTSB docket for ERA17LA261 for the full record.