(_d_) provide for the recognition of certificates of airworthiness granted under the laws of any British possession or foreign nation which appear to the Board of Trade effective for ascertaining and determining airworthiness; (_e_) prescribe the fees to be paid in respect of the grant of such certificates and in respect of applications therefor; (_f_) provide for the exemption from the provisions of this section of aircraft of any particular class or under any particular circumstances prescribed by the regulations. (3) The regulations of the Board of Trade under this section may in the prescribed manner require the owner of any aircraft in respect of which a certificate of airworthiness has been issued or is recognised under those regulations to submit his aircraft at any time for such tests and examinations as may be prescribed for determining whether the conditions of airworthiness continue to be fulfilled, and may authorise endorsement on any such certificate of the result of such tests or examinations, and the cancellation of any such certificate, or the withdrawal of the recognition thereof, on its being found that such conditions have ceased to be fulfilled, or on failure to comply with any such requirement as aforesaid. (4) If any person navigates or allows to be navigated any aircraft (other than an aircraft of an exempted class) in respect of which a certificate of airworthiness granted or recognised under this section is not for the time being in force, or navigates or allows to be navigated an aircraft in respect of which such a certificate is for the time being in force, knowing that the prescribed conditions of airworthiness have ceased to be fulfilled, he shall be guilty of a misdemeanour: Provided that this sub-section shall not, nor shall any proceedings taken thereunder, affect any liability of any such person to be proceeded against by indictment for any other indictable offence. CERTIFICATION OF OFFICERS 5—(1) Every aircraft when being navigated shall be provided with a navigator duly certificated in accordance with this section, and also, in such cases as may be prescribed by regulations made by the Board of Trade, with such other officers so certificated as may be prescribed. (2) The Board of Trade may make regulations— (_a_) as to the issue and form of certificates of competency under this section; (_b_) prescribing the cases in which officers other than the navigator are to be certificated, and the number and character of such officers; (_c_) prescribing the qualifications to be possessed for obtaining a certificate as navigator or as officer serving in any other capacity; (_d_) for holding examinations of candidates for certificates and for such examinations being conducted on behalf of the Board of Trade by other bodies; (_e_) as to the issue of new certificates in place of certificates which have been lost or destroyed;