Boost tabs have been employed on full-scale airplanes of much later vintage than the China Clippers. The DC-9, which later became the MD-80, uses a combination of boost tabs and servo tabs to control its ailerons and elevators. The elevators and ailerons are statically counterbalanced. The pilot has direct cable manual control solely over the servo tab, which is assisted by a separate boost tab. The result is relatively light control forces, weight reduction, and excellent feel. Should hydraulic oil be lost, the airplane remains fully controllable - a boost to safety as well.