Flying an airplane without control surfaces

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There have been aviation incidents in which the control surfaces became unavailable, typically due to loss of hydraulics. Aircraft are not designed to be flown in such circumstances (which is why they have redundant hydraulics), but a few pilots have had some success in controlling such aircraft. The biggest challenge is to avoid the phugoid instability mode, which requires careful use of the throttle.

The basic means of controlling the airplane is by making use of the position of the engine(s). If the engines are mounted under the centre of gravity, as is the case in most passenger jets, then increasing the thrust will raise the nose, while decreasing the thrust will lower it. This control method may call for control inputs that go against the pilot's instinct: when the plane is in a dive, adding thrust will raise the nose and vice versa.

Additionally, asymmetrical thrust may be used for directional control: if the left engine is idled and power is increased on the right side this will result in a yaw to the left, and vice versa. If throttle settings allow the throttles to be shifted without affecting the total amount of power, then yaw control can be combined with pitch control. If the plane is yawing, then the wing on the outside of this yaw movement will go faster than the inner wing. This creates higher lift on the faster wing, resulting in a rolling movement, which helps to make a turn.

Controlling speed is very difficult with engine control only, and this will most likely result in a fast landing, which is required anyway if the flaps can not be extended due to loss of hydraulics, which probably caused the loss of control surfaces in the first place. Only passenger jets with an engine mounted on the tail, such as a DC-10, MD-11 or Lockheed Tristar, will be able to control the speed to a higher degree, as this engine is on the fuselage centreline and above the centre of gravity. On the other hand, planes that have two or four engines mounted on the tail (as is the case with most business jets), will only have limited benefit from asymmetrical thrust.

American Airlines Flight 96, a McDonnell Douglas DC-10, on June 12, 1972. The failure of the rear cargo door caused an explosive decompression, which in turn caused the rear main cabin floor to collapse and severed flight controls. The pilots had only limited ailerons and elevators; the rudder was jammed. The No. 2 engine also shifted to idle at the time of decompression. The aircraft landed safely at Detroit Metro.
Turkish Airlines Flight 981, a McDonnell Douglas DC-10, on March 3, 1974. The failure of the rear cargo door caused an explosive decompression, which in turn caused the rear main cabin floor to collapse and severed flight controls. The No. 2 engine also flamed out at the time of decompression. Unlike American Airlines Flight 96, however, the pilots were left with no functioning controls whatsoever, and all aboard perished.
Japan Airlines Flight 123 on August 12, 1985. A maintenance error years earlier had weakened the aircraft's rear pressure bulkhead, which failed in flight. The vertical stabilizer and much of the aircraft's tail was blown off during the decompression. The pilots were unable to regain full control of the aircraft; all but four aboard perished.
United Airlines Flight 232 on July 19, 1989. A fan disk in the No. 2 engine fractured, severing most of the flight controls. Dennis Fitch, a deadheading DC-10 instructor who had studied the case of JAL Flight 123, was able to help the pilots fly the aircraft in a limited fashion. 185 of those aboard survived.
Philippine Airlines Flight 434 on December 11, 1994. The hydraulics were damaged by a bomb in the passenger cabin.
DHL Flight on 22 November, 2003. This was the first jet airliner to land safely without any hydraulics.