What feature is NOT typically found in a complex airplane?

In a complex airplane, the defining characteristics are features that enhance performance and require a higher level of pilot training and skill. Retractable landing gear, wing flaps, and controllable pitch propellers are all features commonly found in complex airplanes, contributing to improved aerodynamics, performance during takeoff and landing, and overall engine efficiency.

Single engine operation, however, is not specific to complex airplanes. Many types of airplanes, including those that are not considered complex, can operate with a single engine. Therefore, this aspect does not define complexity. The concept of a complex airplane generally focuses on the inclusion of more advanced systems that necessitate specialized training to operate effectively and safely. Thus, the absence of a defining feature, like the complexity that comes with multi-engine configurations or specific advanced flight systems, clarifies why single engine operation is not a typical characteristic associated with complex airplanes.