The assessment of the EU–US open skies agreement: the counterfactual and other difficulties

The advent of the EU–US Open Skies Agreement has been widely anticipated. A number of consequences have been predicted, for example, impacts on fares, on passenger volumes, choice and on consumer welfare. Airline costs are also predicted to fall as a result of increased competitiveness and increased cooperation among airlines. In the short period since the implementation of the Agreement, it is relatively easy to assess the supply-side changes that have been made, but more difficult to make wider judgements. For example, can traffic growth be attributed to Open Skies and does airline and alliance market power result in less fare flexibility with consequently less influence on changes in passenger volumes? Have airline costs changed and what has been the source of the savings? This paper offers some insight into the data that will be required to make these and other wider judgements and discusses some methodological difficulties