(a) This subpart sets forth the special rules applicable to proceedings for the establishment of mail rates by the Department for foreign air transportation and air transportation between points in Alaska, and certain contractual arrangements between the U.S. Postal Service and certificated air carriers for the carriage of mail in foreign air transportation entered into pursuant to 39 U.S.C. 5402(a), 84 Stat. 772.

(b) Such contracts must be for the transportation of at least 750 pounds of mail per flight, and no more than five (5) percent, based on weight, of the international mail transported under any such contract may consist of letter mail.