Which component provides flight control for the AIM-9X?

• A. Fin actuator unit (FAU)
• B. Fin stabilizing fin
• C. Guidance control module
• D. Reaction control thruster

Answer: (A)

Flight control is achieved by actively moving the fins to steer the missile. The Fin Actuator Unit houses the servo actuators that physically deflect the control fins in response to guidance commands, producing the necessary moments about the missile’s axes to steer toward the target. The fin stabilizing fin is a fixed surface that helps stabilize flight rather than actively steer. The guidance control module computes what deflections are needed but does not move the fins itself. The reaction control thruster would provide attitude control with propulsion, which isn’t used on this missile. So the Fin Actuator Unit is the component that provides the actual flight-control authority by moving the fins.