We estimate a conditional logit model to measure the impact of airport and airline supply characteristics on the air travel choices of passengers departing from one of three San Francisco Bay area airports and arriving at one of four airports in greater Los Angeles in October 1995. Non-price characteristics like airport access time, airport delay, flight frequency, the availability of particular airport-airline combinations, and early arrival times are found to strongly affect choice probabilities. Marginal effects and counterfactual scenarios suggest that changes access in times affect travel choices more than changes in travel delays, and that the preferred airport differs by passenger type. In order to examine the robustness of the conditional logit model, we estimate a mixed logit model, and find that the results are similar. We attribute the similarity to our strictly defined travel market and to our distinction between leisure and business travelers, thus controlling for two important sources of consumer heterogeneity.