Institute of Transportation Studies at UC Berkeley

At a national level it is common to express the amount of air travel in terms of the number

of revenue passenger miles flown or the number of enplaned passengers. This provides a way to

resolve the difficulty of how to aggregate measures of air travel in many different markets of

many different distances. However, information about the distribution of trip lengths is lost in the

process.

This information is of interest for a number of reasons. The type of aircraft that is most

appropriate for different markets depends on the distances involved. The length of the trip is also

likely to influence traveler behavior in terms of the importance of convenient access to airports,

frequency of service, and willingness to make intermediate stops.

A related issue is how the cost of air travel varies with the length of the trip. The cost

structure of airline service is such that the cost per mile flown reduces with increasing trip length,

and this is reflected in typical airline fares. However, other factors also influence fares, such as airline competition, and the fare structure may or may not reflect the costs involved for trips of

different lengths.

Therefore, this study examines the distribution of trip lengths and associated average fares

in the U.S. domestic air travel market. For the purpose of this study, trip length is defined as the

direct distance between the origin and destination of a trip. In practice, passengers may fly via

intermediate stops, as when they take a connecting flight through an airline hub, and this will generally increase the distance flown. However, this aspect of trip length is not considered here.