Article 18 Power to prevent aircraft flying

If it appears to the CAA or an authorised person that any aircraft is intended or likely to be flown in such circumstances that articles 4(2), 8(2), 9(2) or 10(2) would be contravened, the CAA or that authorised person may direct the operator or the commander of the aircraft that he is not to permit the aircraft to make the flight or any other flight of such description as may be specified in the direction, until the direction has been revoked by the CAA or by an authorised person, and, if the aircraft is in the United Kingdom, the CAA or that authorised person may take such steps as are necessary to detain the aircraft.

The operator or, as the case may be, the commander of an aircraft shall comply with any direction given to him pursuant to paragraph (1), unless he has reasonable excuse.

For the purposes of paragraph (1), the CAA or any authorised person may enter upon and inspect any aircraft.