Which part of the aircraft does the angle of incidence relate to?

The angle of incidence is a critical aspect of an aircraft's wing design, referring specifically to the angle between the chord line of the wing and the horizontal plane of the aircraft's fuselage. This angle is fixed and is established during the design and construction of the aircraft. It plays a significant role in determining the aircraft's aerodynamic properties, affecting lift, drag, and overall flight performance. A higher angle of incidence can increase lift but also increases drag, which is vital for achieving desired flight characteristics during takeoff, cruising, and landing phases.

Considering the other options, while the tail contributes to overall stability and control, and the fuselage and landing gear have significant functions in structural integrity and ground operations, they do not directly relate to the definition or implications of the angle of incidence as that concept specifically pertains to wing design and performance.