The Comprehensive Annual Financial Report (CAFR) for FY2014 is out. So far the document is only accessible as part of the December 8 council meeting agenda, but at some point will probably appear on the city’s downloads page under the Finance title.
Let’s stick a toe in by first visiting the DeKalb Taylor Municipal Airport (DTMA) annual operating deficits:
The city has to make up for the deficits using tax money that would otherwise go to general operations.
DTMA took on fuel sales a couple years ago, and all of its hangar space is rented out (PDF p. 143). I do not know whether the city has recently compared rental rates with other airports, but if not that might be a good next step to ensure that taxpayers aren’t subsidizing operations any more than they have to.