SEA01IA113 · Cessna 172S

The aircraft was on an instrument training flight at the time of the occurrence. The flight was cleared to an altitude of 6,000 feet on departure. The trainee reported that as the aircraft climbed through 4,500 feet, with the instructor flying the aircraft, "the airplane pitched up, and rolled to the left followed by a pitch down, and a roll back to wings level, then a pitch back up and to the left." The instructor stated that as the aircraft climbed through that altitude, "the aircraft suddenly nosedived for about 3-4 seconds and pitched up into a climb." Both pilots reported that they susbsequently felt the pitch control stuck in a pitch-up position, and that they had to hold forward pressure to hold the nose down (the instructor stated both pilots had to apply full forward pressure to prevent a stall.) The instructor further reported that the aircraft would not roll; the trainee reported that the controls were stuck in roll to the left. The pilots reported that the instructor subsequently attempted to trim the aircraft nose-down, without success. The pilots declared an emergency with ATC and subsequently elected to land in a field directly in front of the aircraft by utilizing rudder and power for control, which they accomplished successfully. The pilots reported in their initial interview with the FAA inspector that they did not have the autopilot on at the time of the occurrence, and that they made no attempts to disengage the autopilot during the incident. Post-incident examinations of the flight controls, trim, and autopilot operation by the operator, an FAA inspector, and the autopilot manufacturer did not disclose any evidence of malfunctions or abnormal flight control or autopilot operation.

Verbatim NTSB analysis and probable cause from the NTSB dataset