Once you understand the concepts behind soaring, there is still one question to be answered—how do sailplanes become airborne? Unlike a bird, the sailplane is at a disadvantage—it cannot flap its wings to take off from the ground. There are several methods by which sailplanes can be launched, most commonly, the aerotow method and the winch method. An aerotow involves the sailplane being attached to a towplane by a strong rope then towed into the air. The cable between glider and towplane is then released by the sailplane pilot when the desired altitude is achieved. A winch launch involves the sailplane being attached to a winch by a long wire. When the wire is pulled in, the sailplane is able to attain enough speed to fly into the air like a kite—at which point the pilot releases the cable and the sailplane is airborne. Some sailplanes are equipped with engines that allow for independent take off. These engines are then turned off once the desired altitude is reached enabling the aircraft to function, as would any other sailplane—soaring using only currents of air.