Information on air passenger flows is potentially a prime data source for assessing spatial patterns in the global city network, but previous analyses have been hampered by inadequate and/or partial data. The ensuing analytical deficiencies have reduced the overall value of these analyses, and this paper examines how some of these deficiencies may be rectified. First, we review the rationale for using airline data to analyse the global city network. Second, we assess the data problems encountered in previous research. Third, we elaborate on the construction of datasets that may circumvent some of these problems. The proposed refinements include the omission of the hub function of major airports and ways to extract relevant business flows from the data.