49 U.S.C. § 48104 - U.S. Code - Unannotated Title 49. Transportation § 48104. Operations and maintenance

(1) direct costs the Secretary incurs to flight check, operate, and maintain air navigation facilities referred to in section 44502(a)(1)(A) of this title safely and efficiently; and

(2) the costs of services provided under international agreements related to the joint financing of air navigation services assessed against the United States Government.