The crew observes the stabilizer trim moving even when the autopilot is disengaged.

• A. Elevator System Jammed
• B. Rudder System Jammed
• C. Stabilizer Trim Runaway
• D. Unreliable Airspeed

Answer: (C)

When the stabilizer trim keeps moving even after the autopilot is disengaged, you’re looking at a trim runaway. The trim motor is still driving the stabilizer without a commanded input, which points to a fault in the trim control circuit or the trim motor itself. That continuous, uncommanded motion is the hallmark of a runaway condition.

This isn’t consistent with an elevator or rudder jam. If those surfaces were jammed, you’d expect them to be stuck or resisting movement rather than the trim continuing to move on its own. And unreliable airspeed doesn’t directly cause ongoing trim motion once the autopilot is off.

In this situation the appropriate response is to isolate or cut power to the stabilizer trim system (for example, by switching off the trim or pulling the trim circuit breaker if equipped) and follow appropriate SOPs to control the aircraft manually and notify maintenance.