Available Seat Miles (ASM): The ASM metric is used to track seat supply among airlines. ASM is equal to the number of available seats times the number of miles flown.
Revenue Seat Miles (RPM): RPM measures the number of seat miles flown for which the company earned revenues. That is, RPM equals the number of filled seats times the number of miles flown.
Load Factor: The percentage of available seats that are filled during a specific period is an airline's load factor for that period. In 2007 load factors for major airlines ranged from 72-84%.
Yield: The amount of revenue earned per RPM is known as the airline's yield. This metric is generally expressed in cents and ranged from 9.8-13.1 cents for the major airlines in the first half of 2007.