In 1948, Boeing reactivated its Wichita plant, nearly idle since the war ended, to convert B-29s into KB-29M tankers. The KB-29Ms used a hose-type aerial fueling requiring a slow airspeed and which was difficult in poor weather. Boeing developed the flying boom, an aerodynamically controlled swiveling and telescoping arm that a crew member, using cockpit-like flight controls, guided into a receptacle on top of the receiving aircraft's fuselage. KB-29P tankers, B-29s equipped with the Boeing flying boom, began operation in 1950. The boom became the primary method of aerial fueling and was later used on KC-97s and K-135 jet tankers.