Cessna 172N N6238D accident near Charleston, West Virginia

Probable cause

The flight instructor's failure to ensure that her seat was properly secured before initiating the takeoff, which resulted in a subsequent loss of control. Contributing was the lack of an installed secondary seat stop.

NTSB analysis

The flight instructor, who was controlling the airplane, and the student pilot were conducting an instructional flight. During the takeoff the airplane lifted off about 1,000 ft down the runway, pitched nose up, and rolled left to an inverted attitude before it impacted terrain next to the runway in a nose-down attitude. The student pilot recalled that as the airplane rotated during the takeoff, he heard the flight instructor exclaim, but could not recall any subsequent events. Postaccident examination of the flight controls revealed no evidence of any preimpact mechanical malfunctions or failures that would have precluded normal operation.

Examination of the wreckage revealed witness marks along the flight instructor's seat tracks that corresponded with the seat in the nearly full-aft position. Given the flight instructor's stature, it is unlikely that this position would allow her to fully actuate the flight controls, and it is therefore unlikely she purposefully initiated the takeoff with her seat in this position. While one of the two locking pins that would have secured the seat from sliding fore and aft was found fractured, it is likely that the jockeying of the seat during the victim extraction process resulted in the fracture of the locking pin, and left the witness marks observed on the seat track. Examination of the wreckage and maintenance documents also revealed that the airplane was not equipped with a manufacturer-recommended secondary seat stop mechanisms for either of the pilot seats.

Review of operational and maintenance documents published by the airframe manufacturer showed the critical importance of ensuring that the pilot seats were secured prior to initiating a flight, and that accelerations such as those encountered during a takeoff could dislodge an unsecured seat. Had the flight instructor, who was performing the takeoff, not properly secured her seat prior to initiating the takeoff, it may have resulted in her seat sliding aft, and her inadvertent application of control inputs to the control yoke during the rotation and initial climb, consistent with steep climb, descent, and impact. The aft seat position could have also likely resulted in her inability to apply complete or sufficient control inputs to the rudder pedals, consistent with the left yaw/roll observed during the takeoff.

Text from the NTSB. Open the NTSB docket for ERA16FA141 for the full record.