# The Air Navigation Order 2016, Paragraph 1


A non-Part-21 aircraft may fly for a purpose set out in paragraph 2 subject to the conditions set out in paragraphs 3 to 6 whether or not it is registered in accordance with article 24(1) when there is not in force—
(a) in the case of an aircraft which is so registered, a certificate of airworthiness duly issued or rendered valid under the law of the country in which the aircraft is registered; or
(b) in the case of an aircraft which is not so registered, either a certificate of airworthiness duly issued or rendered valid under the law of the United Kingdom or a permit to fly issued by the CAA for that aircraft.

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Source: https://www.legislation.gov.uk/uksi/2016/765/schedule/3/part/1/chapter/2/paragraph/1 (the official version)
Page: https://openlegislation.uk/air-navigation-order-2016/schedule-3/part-1/chapter-2/paragraph-1
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.