Which system prevents the AIM-120 rocket motor from becoming propulsive?

• A. Thermally initiated venting system
• B. Automatic ignition suppressor
• C. Mechanical brake system
• D. Venturi throttle control

Answer: (A)

Preventing unintended propulsion in a solid rocket motor relies on a safety feature that vents the motor chamber when exposed to abnormal heat. The thermally initiated venting system automatically opens to release propellant gases if temperatures rise, so the motor cannot reach ignition or produce thrust even in a fire or other heat event. This protects against accidental propulsion during handling or storage. Other options don’t provide this automatic venting response: an ignition suppressor targets the igniter, not the venting of the chamber; a mechanical brake would slow moving parts but not stop the chemical reaction; and a venturi throttle control would alter exhaust flow, not serve as a safety mechanism to prevent propulsion under abnormal conditions.