Paragraph 4 Reporting hazardous conditionsI1

If any aircraft encounters hazardous conditions in the course of a flight, the pilot-in-command of the aircraft must send to the appropriate air traffic control unit, by the quickest means available, information containing such particulars of the hazardous conditions as may be pertinent to the safety of other aircraft.

The information must be sent immediately the aircraft encounters the hazardous conditions or as soon as it is possible to do so afterwards.