The invention relates to an automatic takeoff method for an aircraft with a flexible airfoil, comprising a carriage suspended by rigging lines from an airfoil. According to said method: —said carriage is provided with an autopilot controlling actuators that control said rigging lines; —said airfoil is provided with an airfoil attitude sensor, comprising a biaxial accelerometer and a biaxial rate gyro, capable of defining the position of an airfoil reference frame in relation to the ground, and means for communicating with said autopilot; —during takeoff, information is received from said airfoil attitude sensor and transmitted to said autopilot for the purpose of controlling said actuators. The invention also relates to an airfoil for the implementation of said method, comprising an airfoil attitude sensor with an inertial unit with a biaxial accelerometer and a biaxial rate gyro, and means for communicating with an autopilot. The invention further relates to an aircraft comprising such an airfoil.