DEFINITION of 'Available Seat Miles - ASM'
A measure of an airplane's carrying capacity available to generate revenue. Available seat miles refers to how many seat miles are actually available for purchase on an airline. Seat miles are calculated by multiplying the available seats for a given plane by the number of miles that plane will be flying for a given flight.
BREAKING DOWN 'Available Seat Miles - ASM'
ASM is simply a measure of a flight's revenue-generating abilities based upon traffic. For investors analyzing airlines, ASM is a very important metric in deciding which airlines are best at generating revenue from the availability of seats to customers. If all of the seats on the plane are not sold, then the ASM of the airline is operating at below capacity. Long instances of unavailable seats on an airline can cost an airline millions of dollars.