Definition
An airplane equipped with a retractable landing gear, flaps, and a controllable-pitch propeller; for seaplanes, an airplane with flaps and a controllable-pitch propeller. A single-engine airplane with a full authority digital engine control (FADEC) system meeting these performance characteristics is also considered complex for training and endorsement purposes.
Plain English
An airplane that has wheels you can pull up into the fuselage, wing flaps, and a propeller whose blade angle can be adjusted in flight. These extra systems make it more capable, but also give the pilot more to manage.
Context Anchor
You will see this term when reading about transition training, aircraft endorsements, and operating airplanes with retractable gear and adjustable propellers.
Derivation
From Latin complexus, meaning 'woven together' or 'made of connected parts.' The name fits: a complex airplane has several systems working together that the pilot must manage at the same time.
Why Pilots Care
A pilot must receive specific flight instruction and a logbook endorsement before acting as pilot in command of a complex airplane for most certificate and rating purposes.
Intuition Check
Complex does not simply mean “difficult” here. In this FAA context, it means the airplane has specific equipment: retractable landing gear, flaps, and an adjustable or electronically managed propeller.
Example Sentence 1
Before her checkout in the Piper Arrow, Sarah received a complex airplane endorsement from her instructor.
Example Sentence 2
Before the checkride the applicant had to show that he could safely manage all systems on the complex airplane during takeoff, cruise, and landing.