Mechanical & Engine Failure · NTSB WPR18FA195
Cessna 172 — Deer Park, WA
| Date | July 13, 2018 |
| Location | Deer Park, WA |
| Aircraft | Cessna 172 |
| Purpose of flight | Instructional |
| Conditions | Day · Visual Meteorological Cond |
| Phase / occurrence | Maneuvering Part(s) separation from AC |
| Pilot age | 30 |
| Pilot total time | 1,054 hrs · Experienced |
| Time in type | 502 hrs |
| Fatalities | 3 |
Probable cause
NTSB findings
- Environmental issues-Physical environment-Object/animal/substance-Animal(s)/bird(s)-Contributed to outcome - C
- Personnel issues-Task performance-Use of equip/info-Aircraft control-Instructor/check pilot
- Aircraft-Aircraft structures-Wing structure-Flight surfaces (wing)-Capability exceeded
- Aircraft-Aircraft oper/perf/capability-Performance/control parameters-Descent rate-Capability exceeded
What happened
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.