Gyro rotation Resultant force on gyro Yaw force Aircraft yaw rotation Gimbal rotation Figure 10-106.  The turn-and-slip indicator’s gyro reaction to the turning force in a right hand turn. The yaw force results in a force on  the gyro 90° around the rotor in the direction it is turning due to precession. This causes the top of the rotor to tilt to the left. Through  connecting linkage, the pointer tilts to the right.  Autopilot Systems Basis for Autopilot Operation 10-61 The basis for autopilot system operation is error correction.  When an aircraft fails to meet the conditions selected, an error  is said to have occurred. The autopilot system automatically  corrects that error and restores the aircraft to the flight attitude  desired by the pilot. There are two basic ways modern  autopilot systems do this. One is position based and the  other is rate based. A position based autopilot manipulates  There are many autopilot systems available. They feature  a wide range of capabilities and complexity. Light aircraft  typically have autopilots with fewer capabilities than high- Autopilot systems provide for one-, two-, or three-axis control  of an aircraft. Those that manage the aircraft around only  one axis control the ailerons. They are single-axis autopilots,  known as wing leveler systems, usually found on light aircraft.  [Figure 10-107]  Other autopilots are two-axis systems that  control the ailerons and elevators. Three-axis autopilots  control the ailerons, elevators, and the rudder. Two-and three- axis autopilot systems can be found on aircraft of all sizes. The primary purpose of an autopilot system is to reduce the  work strain and fatigue of controlling the aircraft during long  flights. Most autopilots have both manual and automatic  modes of operation. In the manual mode, the pilot selects  each maneuver and makes small inputs into an autopilot  controller. The autopilot system moves the control surfaces  of the aircraft to perform the maneuver. In automatic mode,  the pilot selects the attitude and direction desired for a flight  segment. The autopilot then moves the control surfaces to  attain and maintain these parameters.  For further automatic control, flight management systems  have been developed. Through the use of computers, an entire  flight profile can be programmed ahead of time allowing the  pilot to supervise its execution. An FMS computer coordinates  nearly every aspect of a flight, including the autopilot and auto  throttle systems, navigation route selection, fuel management  schemes, and more. Some modern small aircraft, high-performance, and transport  category aircraft have very elaborate autopilot systems known  as automatic flight control systems (AFCS). These three-axis  systems go far beyond steering the airplane. They control  the aircraft during climbs, descents, cruise, and approach  to landing. Some even integrate an auto-throttle function  that automatically controls engine thrust that makes auto- landings possible. An aircraft automatic pilot system controls the aircraft  without the pilot directly maneuvering the controls. The  autopilot maintains the aircraft’s attitude and/or direction and  returns the aircraft to that condition when it is displaced from  it. Automatic pilot systems are capable of keeping aircraft  stabilized laterally, vertically, and longitudinally.  performance and transport category aircraft. Integration  of navigation functions is common, even on light aircraft  autopilots. As autopilots increase in complexity, they not  only manipulate the flight control surfaces, but other flight  parameters as well. 