10 U.S.C. § 8413

(a) An aviation cadet who fulfills the requirements of section 2003 of this title may be appointed an ensign in the Navy Reserve or a second lieutenant in the Marine Corps Reserve and designated a naval aviator. (b) Aviation cadets who complete their training at approximately the same time are considered for all purposes to have begun their commissioned service on the same date, and the decision of the Secretary of the Navy in this regard is conclusive.