线控 (有时被称为U-控) 是一种简单轻巧控制模型飞机的方式。操控者使用把手，经由两条线来控制模型飞机的升降舵。此一方法能够操控飞机在俯仰方向上的动作。飞机的飞行则巧妙的经由控线控制在一个半球面上飞行。控线通常是单股线，或是多股线，线的粗细介于0.008英吋(0.2公厘)至0.021英吋(0.53公厘)。有时候会使用第三条线来控制引擎的节流阀，也有使用更多的线来控制其他动作的可能。有时候会借由控线来传递电子信号以控制一些像真模型上的动作，如收放飞机起落架，或是襟翼的控制。大部分的线控飞机动力来源使用传统模型飞机上会看到的动力系统，如引擎、马达。但也有使用无动力的线控飞机，操控方式类似于风筝。

Control line (also called U-Control ) is a simple and light way of controlling a flying model aircraft. The aircraft is connected to the operator by a pair of lines, attached to a handle, that work the elevator of the model. This allows the model to be controlled in the pitch axis. It is constrained to fly on the surface of a hemisphere by the control lines. There is also a control system that uses only a single solid wire that is twisted around its own axis, that spins a spiral inside the airplane to move the elevator. While it can be used with some success on any type of model, it is best for speed models where the reduced aerodynamic drag of the single line is a significant advantage. The control provided is not as precise as the two-line control system. The control lines are usually either stranded stainless steel cable or solid metal wires of anywhere from 0.008 in (0.20 mm) to 0.021 in (0.53 mm). Sewing thread or fishing line may be used instead of wires to control very small models, but its air resistance is greater. A third line is sometimes used to control the engine throttle, and more lines may be added to control other functions. Electrical signals sent over the wires are sometimes used in scale models to control functions such as retracting undercarriage and flaps. Almost all control-line models are powered with conventional model aircraft engines of various types. But it is possible to fly control-line models that do not use on-board propulsion, in a mode called "whip-powered", where the pilot "leading" the model with his arm and wind supply the necessary energy to keep the airplane aloft, in a fashion similar to kite-flying.