To allow the Dash 7 to achieve its excellent STOL characteristics, the aircraft employs many aerodynamic devices. The wing flaps are double-slotted and span about 75% of the trailing edge of the wing. In a typical STOL landing, flaps are set to 45° before landing, which allows for a slower approach speed (typically 70–85 knots) and steeper descent. Upon touchdown, the flaps immediately return to the 25° position, which decreases the lift created by the wing and thereby increasing braking effectiveness. The aircraft also employs two ground spoilers and two roll spoilers per wing. The roll spoilers' primary job is to augment the ailerons, but upon touchdown, all four roll spoilers activate along with all four ground spoilers to spoil much of the lift generated by the wing.