Stall/spin airplane accidents result in a significant number of fatalities each year within the general-aviation community. The most effective method of reducing this type of accident is to prevent airplane stalls. The device described in this report has been shown to be effective in preventing stall of a Piper PA-18, 150 airplane, and it should also be effective on other airplanes. The system incorporates a small spoiler mounted on the under surface of the stabilizer near the elevator hinge line. The spoiler is deployed automatically by means of a servo system that receives its commands from an angle of attack sensor mounting in the wing leading edge. Thus, the operation of the system is independent of pilot reactions. The spoiler deploys to limit tail power near the wing stall angle of attack, thereby preventing the wing from reaching the angle of attack required for stalling.Flight tests have shown the device to be effective in all normal flight conditions by preventing the airplane from stalling. In addition, the stall prevention system increases stick force after deployment at high wing angle of attack.