Each month, the Department of Transportation’s Office of Aviation Enforcement and Proceedings releases its Air Travel Consumer report. The report is divided into four sections, which deal with flight delays, mishandled baggage, oversales and consumer complaints, respectively.

The consumer complaints section summarizes complaints filed with the Department in writing, by telephone, via email, or in person. DOT does not necessarily determine the validity of the complaints.

Most categories of complaint deal with timeliness, lost baggage or the like. But the very last one — “Other” — gives us a sense of who is treating their frequent flyers well, because it includes complaints specifically directed at frequent flyer programs.

To be fair, it’s important to note that the “other” category can include non-program related gripes, including smoking, airport facilities, and cargo problems.

But frequent flyers tend to be a vocal lot, so chances are someone had a falling out with his or her program.

For May of 2003 (the most recent statistics available), United had the most complaints in this category, with a total of eight. Hardly a ringing indictment, given the ridiculously large number of Mileage Plus members.

American and Northwest were runners-up with two apiece. US Airways, Continental, America West and Delta had one apiece.

All told, a total of 17 complaints in the “other” category were logged with the DOT for May — that’s down from 28 a year ago, and when compared with the total number of complaints for May of 2003 (383), it would seem that the programs are doing a solid job of keeping their frequent flyers happy.