Cessna 172 N24442 accident near Deer Park, Washington

Probable cause

An in-flight breakup as a result of the airplane exceeding the structural strength of the airplane during a rapid descent that the flight instructor was unable to recover from following a collision with a large bird.

NTSB analysis

The purpose of the flight was for the student pilot to make his first flight in his training program, with the flight instructor and an observer also onboard the airplane. There were no aggressive maneuvers planned during the flight. Radar data indicated that, following departure, the airplane flew about 25 minutes making a series of benign turns. With the airplane maneuvering in a level attitude, configured at 77 kts (ground speed), it suddenly made a sharp 90° right turn and rapidly descended; the last speed recorded was 117 kts. The airplane was in a steep dive as it approached the accident site and just before impact, the outboard wings broke off the airplane about the same time.

Postaccident examinations revealed no anomalies with the airplane. Flight control system continuity could not be definitively confirmed due to the fragmentation of the wreckage, but the fractured control cables all showed signatures consistent with overload.

Numerous pieces of the windscreen and swabs of the airframe were sent to the Smithsonian Institution's Feather Identification Lab. Found within the samples were a partial feather and the microscopic downy feather characters, which were consistent with an American white pelican, which has an average weight of 7.7 kg. There were many observations of American white pelicans reported near the area around the date of the accident.

The airplane manufacturer’s recommended maneuvering speed was about 97 kts and abrupt control movements above that speed could impose excessive loads beyond the structural strength of the airplane. The airplane likely collided with an American white pelican resulting in a rapid descent that the flight instructor was unable to recover from before the airplane exceeded the manufacturer’s recommended maneuvering speed, which led to the exceedance of the airplane's structural strength capability and breaking up in-flight.

Text from the NTSB. Open the NTSB docket for WPR18FA195 for the full record.