The purpose of forecasting• Short-term forecast◦ Total passenger enplanements between a particular pair of cities.◦ A basis for determining station personnel and ground equipment needed, gate availability, and expenses.◦ One-month to one year, summer and winter schedule• Medium-term forecast ◦ Route planning decision ◦ One to five years• Long-term forecast◦ Fleet planning decision and long-term financial commitments. ◦ Five to ten years