large ships, an emergency stop button pulls the countershaft for the fuel pumps to the stop position, cutting off the fuel supply and stopping the engines. With a controllable-pitch propeller, the stop button may declutch the engine from the propeller. NASCAR requires all their stock cars to be equipped with a steering wheel-mounted kill switch, in case the accelerator pedal sticks and the driver needs to shut down the engine. A related concept is the dead man's switch, where the operator must be holding a button or lever any time the vehicle is operating. A common example of this is the kill switches used by boaters and jetskiers wherein a cord connects the kill switch to the operator (usually by the operator's life jacket or clothing), and if the operator is thrown overboard in an accident, the cord will pull the switch and immediately shut down the vessel's engine. This prevents it from becoming a runaway vessel that could impose a danger to other vessels or swimmers at sea, and allows the operator to swim back to the vessel and re-board it without the risk of being injured by the boat's propeller. A similar device is featured on most lawnmowers: a lever on the handle either disables the ignition system and applies a brake to the flywheel (on a gasoline lawnmower), or cuts the power to the motor (on an electric lawnmower), as long as it is not held down. Monster Truck Racing Association requires all of their monster trucks to be equipped with kill switches (either remote or in cab), in case the monster truck loses control and the driver needs to shut off the engine. Monster trucks' kill switches are tested before races. Pioneer-era planes and World War I aircraft Early aviators using rotary engine-powered aircraft from the beginnings of their use in 1908, up through the end of World War I in 1918 had what could be called a reversed functionality version of the "dead man's switch" for cutting the ignition voltage to the spark plugs on such a power-plant, to give a degree of in-flight speed control for a rotary engine. This was often called a "blip switch" or "coupe switch" (from the French term coupez, or "cut") and when not being pressed, allowed the high voltage from the engine's magnetos to operate the ignition with normal engine operation in flight — pressing the "blip switch"