1492
THE NEW ZEALAND GAZETTE.
[No. 41

or with any sound apparatus. In addition it shall make by international Morse code by means of sound or luminous signals the two-letter group composed of the first letter and the last letter of the five-letter group constituting its nationality and registration marks.
(b) Permission to land will be given by the same two-letter sign from the ground, made with a green light and followed by intermittent signals of the same colour.
15. The firing of a red pyrotechnical light or the display of a red flare from the ground shall be taken as an instruction that aircraft are not to land.

Aircraft compelled to land at Night.

16. An aircraft compelled to land at night shall, before landing, make a series of short and intermittent flashes with its navigation lights.

Aircraft in Distress.—Signals.

17. When an aircraft is threatened by grave and imminent danger and requires immediate assistance, the following shall be the signals of distress to be used, or displayed either together or separately :—
    (a) The international signals, S O S, by means of visual or radio-telegraphic signals ;
    (b) The international distress call “ MAYDAY ” (corresponding to the French pronunciation of the expression “ m’aider ”) by means of radio-telephony.
    (c) The international code flag signal of distress indicated by N.—C.
    (d) The distant signal, consisting of a square flag having either above or below it a ball, or anything resembling a ball.
    (e) A continuous sounding with any sound apparatus.
    (f) A signal consisting of a succession of white pyrotechnical lights fired at short intervals.
18. (a) Where an aircraft has a message to send stating that it is in difficulties and about to land compulsorily, but does not require immediate assistance, it shall preface its call sign with several repetitions of the urgency signal PAN.
    (b) Where the signal PAN is received from an aircraft without any message following, it shall signify that the aircraft has been compelled to land, and is unable to transmit its intended message owing to the rapidity of the landing, but does not require immediate assistance.
    (c) Where the signal PAN is sent by radio-telegraphy, the three letters shall be well separated so that the signals AN are not transformed into one signal P.
19. Where an aircraft has a very urgent message to send concerning the safety of the aircraft, or of any person on board, or of any ship, aircraft, vehicle, or person within sight, it shall, for the purpose of indicating the urgency of the message, preface its call sign with several repetitions of the group XXX, the letters of each group being clearly separated from the letters of the successive group.
20. Neither the signal PAN nor the signal XXX may be transmitted except with the authority of the commander or person responsible for the aircraft.

Navigational Messages.

21. Where an aircraft has a message to send concerning the safety of navigation or containing important information relative to meteorological warning messages, it shall preface its call sign by the safety signal, consisting of the group TTT (transmitted with the letters well separated) followed by the word DE.

Warnings in Vicinity Prohibited Areas.

22. To warn an aircraft that it is in the vicinity of a prohibited area, and should change its course, the following signals shall be used :—
    (a) By day—Three projectiles discharged at intervals of 10 seconds, each showing on bursting white smoke, the location of the burst indicating the direction the aircraft should follow ;
    (b) By night—Three projectiles discharged at intervals of 10 seconds, each showing on bursting white lights or stars, the location of the burst indicating the direction the aircraft should follow.

Aircraft required to Land.

23. To require an aircraft to land, the following signals shall be used :—
    (a) By day—Three projectiles discharged at intervals of 10 seconds, each showing on bursting black or yellow smoke ;
    (b) By night—Three projectiles discharged at intervals of 10 seconds, each showing on bursting green lights or stars ;
    (c) In addition, where necessary to prevent the landing of aircraft other than the one ordered, a searchlight, which shall be flashed intermittently, shall be directed towards the aircraft whose landing is required.

Fog Signals.

24. (a) In the event of fog or mist rendering aerodromes invisible, their presence may be indicated by a balloon acting as an aerial buoy and/or other approved means.
    (b) In fog, mist, falling snow, or heavy rainstorms, whether by day or night, an aircraft on the water shall make the following sound signals :—
    (i) If not anchored or moored, a sound at intervals of not more than two minutes, consisting of two blasts of about five seconds duration, with an interval of about one second between them ;
    (ii) If at anchor or moored, the rapid ringing of an efficient bell or gong for about five seconds at intervals of not more than one minute.

Use of Station and Signal Lights, &c.

25. Nothing in this part shall prevent—
    (a) The use, in respect of military aircraft, or aircraft in formation, of additional station and signal lights ;