How does the FARs define a complex airplane?

A complex airplane is defined by the Federal Aviation Regulations (FARs) as one that is equipped with retractable landing gear, flaps, and a controllable-pitch propeller. This definition is important for pilots as operating a complex airplane requires additional training and endorsements due to the increased complexity and operational demands associated with these features.

Retractable landing gear enhances aerodynamic efficiency and can improve performance but requires the pilot to have knowledge and skills to operate the gear system properly. Flaps are critical for controlling lift during takeoff and landing and also require understanding how to deploy them effectively for various phases of flight. A controllable-pitch propeller allows for greater efficiency and performance by enabling the pilot to adjust the pitch of the propeller blades in flight, enhancing climb rates and fuel efficiency.

In contrast, airplanes with fixed-pitch propellers and fixed landing gear do not meet this definition, as they lack the complexity that necessitates additional training. Similarly, the criteria concerning passenger capacity or aerobatics do not pertain to the specific definition of a complex airplane within the regulations. Understanding these definitions is critical for safe and efficient flight operations.