Activity levels at airports are measured by aircraft operations. An operation is defined by the FAA as a takeoff or a landing. So, a “touch and go” conducted by a training aircraft counts as two operations. In 2005, Centennial Airport accommodated 344,619 aircraft operations. That’s a takeoff or landing every 80 seconds. However, most of the traffic is concentrated in the daytime hours. The record year at Centennial occurred in 1998, with over 466,000 aircraft operations.