Records show Tennessee economic development officials have taken dozens of flights on state planes this year,  the purpose for some of the trips is not clear. Between January and July, state officials took about 580 flights on five state-owned planes,  which the Tennessee Department of Transportation keeps records. A few other parts of state government also have their own aircraft. The Tennessean reports that about 150 of those flights were charged to Tennessee Department of Economic and Community Development for events ranging from ribbon-cuttings to groundbreaking ceremonies. The purpose of some flights, however, is not always obvious. The agency considers documents that make virtually any reference to corporate business deals to be privileged tax information, and therefore confidential. The flights typically cost several hundred dollars an hour.