A Fixed Based Operator is a retail firm that sells general aviation products or services at an airport. The FBO may employ one or more employees or may have a hundred workers. One or more services are offered at a FBO: fueling; aircraft, avionics and or instrument sales and service; flight training; air taxi service and charter flights; and aircraft exterior and or modification.

Depending on the size and scope of the airport's operation, the FBO employs aviation mechanics, flight instructors, and aircraft sales persons. It may employ a licensed aviation mechanic to train and supervise mechanics. FBO personnel will often arrange for ground transportation and overnight accommodations for general aviation pilots and their passengers.