10 U.S.C. § 18505: Reserves traveling for inactive-duty training: space-required travel on military aircraft

(a) A member of a reserve component traveling for inactive-duty training (including a place other than the place of the member’s unit training assembly if the member is performing inactive-duty training in another location) may travel in a space-required status on aircraft of the armed forces between the member’s home and the place of the inactive-duty training. (b) A member traveling in a space-required status on any such aircraft under subsection (a) is not authorized to receive travel, transportation, or per diem allowances in connection with that travel.