Any person subject to air-force law who is guilty of drunkenness, whether on duty or not, shall, on conviction by court-martial, be liable to imprisonment for a term not exceeding two years or any less punishment provided by this Act F1.

. . . F2

For the purposes of this section a person is guilty of drunkenness if owing to the influence of alcohol or any drug, whether alone or in combination with any other circumstances, he is unfit to be entrusted with his duty or with any duty which F3he might reasonably expect to be called upon to perform, or behaves in a disorderly manner or in any manner likely to bring discredit on Her Majesty’s service.