(1)A person in air-force service who enlisted otherwise than on a long-term enlistment may, on written application in that behalf made by him to his commanding officer and with the consent of the competent air-force authority, be treated for the purposes of this Act, but subject to the provisions of this section, as if, on the date of his attestation, he had enlisted on a long-term enlistment.
(2)A person shall not give a notice under the foregoing subsection before attaining the age of seventeen years and six months.
(3)Subsection (1) of the last foregoing section shall not apply to a person who by virtue of this section is treated as if he had enlisted on a long-term enlistment unless his application under subsection (1) of this section is made before he has completed four years' service, and, in relation to a person who is so treated, the last foregoing section shall have effect as if, at the end of subsection (1) thereof, there were added the words " or the term for which he originally enlisted, whichever last expires ".
(4)In reckoning for the purposes of the last foregoing subsection the period of service completed by any person, there shall be included, in addition to any period served by him in air-force service since the relevant date, any period served by him since that date in the reserve and, if before his attestation he has at any time served as an officer or airman of the regular air force in air-force service or in the reserve, or the Royal Auxiliary Air Force, any period so served by him before his attestation other than—
(a)any period served while undergoing training as an officer or airman of the reserve or the Royal Auxiliary Air Force, or
(b)any period served before attaining the age of eighteen years in service in the regular air force as an apprentice or a boy entrant.