Chapter 11 Transition to  Complex Airplanes  Introduction A high-performance airplane is defined as an airplane with an  engine capable of developing more than 200 horsepower. A  complex airplane is an airplane that has a retractable landing  gear, flaps, and a controllable pitch propeller. In lieu of a  controllable pitch propeller, the aircraft could also have an  engine control system consisting of a digital computer and  associated accessories for controlling the engine and the  propeller. A seaplane would still be considered complex if it  meets the description above except for having floats instead  of a retractable landing gear system.