D.C. Code § 9-917
The Authority may fix, revise, charge, and collect fees or other charges for the use of the airports, contract with any person, partnership, association, or corporation desiring the use of any part of the airports, including the right-of-way adjoining the airports for placing on the airports telephone, telegraph, electric light or power lines, and fix the terms, conditions, rents and fees or other charges for use. Fees or other charges shall be so fixed and adjusted in respect of the aggregate of fees or other charges form the airports as to provide a fund sufficient with other revenues, if any, (1) to pay the cost of maintaining, repairing and operating the airports, (2) to pay the principal of and interest on bonds as they become due and payable, and (3) to create reserves for these purposes. The fees and other charges and all other revenues derived from the airports, except the part as may be necessary to pay the cost of maintenance, repair, and operation and provide reserves as may be provided for in the resolution authorizing the issuance of the bonds or in the trust agreement securing the bonds, shall be set aside at regular intervals as may be provided in the resolution or the trust agreement in a sinking fund, which is pledged to, and charged with, the payment of the principal of the interest on the bonds as they become due, and the redemption price or the purchase price of bonds retired by call or purchase as provided in the bonds. The pledge shall be valid and binding from the time when the pledge is made. The fees, other charges, and other revenues or other monies so pledged and subsequently received by the Authority shall immediately be subject to the lien of the pledge without any physical delivery of the lien or further act, and the lien of the pledge shall be valid and binding as against all parties having claims of any kind of tort, contract or otherwise against the Authority, irrespective of whether the parties have notice of the lien. Neither the resolution nor any trust agreement by which a pledge is created need be filed or recorded except in the records of the Authority. The use and disposition of monies to the credit of the sinking fund shall be subject to the provisions of resolution authorizing the issuance of the bonds or of the trust agreement. Except as may otherwise be provided in the resolution or the trust agreement, the sinking fund shall be a fund for all these bonds without distinction or priority of 1 over another.
D.C. Code § 9-917