What happened
While descending from FL350 to FL140 in VMC conditions and smooth air, the crew of an MD-11 was operating with the autopilot engaged. As the aircraft approached FL250, the captain expressed concern that the airplane would fail to level off at the assigned altitude of FL240. Following instructions from the captain to reduce the rate of descent, the first officer used the pitch thumbwheel on the autopilot control panel.
The captain then took control of the aircraft and attempted to overpower the autopilot by pulling back on the control yoke. While applying back pressure, the captain disengaged the autopilot. Due to the reduced resistance in the control column following disengagement, the elevators moved further into the up position. Flight data recorder information indicated that the aircraft was subjected to a +2.28 G-load during this event.
The incident resulted in 3 minor injuries: one passenger in the aft lavatory suffered a fractured ankle, while a second passenger and two flight attendants sustained minor injuries.