(1) The signals of distress which shall be used by vessels to which regulation 3(1)(a) apply are those set out in Annex IV to the International Regulations.
(2) Signals of distress shall not be used by any vessel unless the master of the vessel so orders.
(3) The master shall not order any signal of distress to be used by his or her vessel unless he or she is satisfied that—
(a) his or her vessel is in serious and imminent danger, or that another ship or an aircraft or person is in serious and imminent danger and cannot send that signal; and
(b) the vessel in danger, whether that vessel is his or her own vessel or another vessel or the aircraft or person in danger, as the case may be, requires immediate assistance in addition to any assistance then available.
(4) The master of a vessel which has sent any signal of distress by means of radio or other means shall cause that signal to be revoked by all appropriate means as soon as he or she is satisfied that the vessel or aircraft to which, or the person to whom, the signal relates is no longer in need of assistance.