Last month, the appellate court ruled that the tax break for Elliott Aviation was unconstitutional and violated the state's special legislation clause. The company appealed that decision Wednesday.
In February 2013, legislation exempting fixed-base operators leasing land at the Quad City International Airport from taxation was approved by lawmakers and signed by then-Gov. Pat Quinn.
The decision was in response to Elliott Aviation's plans to either expand in Moline or Des Moines, Iowa.
The Moline School District filed a lawsuit questioning the constitutionality of the exemption. Elliott Aviation intervened and won in lower court, but the district appealed.