Scheduled operations exceeded FAA's capacity constraints at only five airports, and only for brief periods of time. In order to determine the capacity levels for departures as well as arrivals at each airport, the AAR was doubled. These values were then compared to the sum of departures and arrivals at each airport in half-hour increments. AAR values are those used by traffic-management computers in the absence of a manual entry being made, and thus are representative of what the rate is at the airports most of the time. Doubling this number to determine capacity is a good average for the day, but may not be exact at specific times during the day.
Controllers adjust the proportion of arrivals and departures at an airport throughout the day.
Since an airport can handle more departures than arrivals in the same period of time, capacity at an airport varies throughout the day. Impact of Weather on Capacity Hub airports, like Atlanta, are characteristically scheduled more tightly than spoke airports, like Orlando. Because passengers make connections through hub airports - more flights are needed at the hubs. There are typically more congestion and peak periods at the hub airports due to this fact. On the other hand, at spoke airports, there are no connecting flights and usually very limited congestion problems.