THE HONG KONG GOVERNMENT GAZETTE, DECEMBER 17, 1937.
20. To require an aircraft to land, the following signals shall be [Schedule used: -
IV,---contd.]
(a) By day, a series of projectiles discharged at intervals of 10 seconds, each showing on bursting black smoke;
(b) By night, a series of projectiles discharged at intervals of 10 seconds, each showing on bursting white lights or stars.
In addition, when necessary to prevent the landing of aircraft other than the aircraft required to land, an intermittent white luminous beam shall be directed at the aircraft whose landing is required.
21. 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, a series of projectiles discharged at intervals of 10 seconds, each showing on bursting orange smoke;
(b) By night, a series of projectiles discharged at intervals of 10 seconds, each showing on bursting orange lights or stars.
Provided that, when the authority requiring the change of course referred to in this paragraph is able to establish radioelectric communication with the aircraft, such requirement may be indicated by that method of communication.
SECTION III.
General Rules for Air Traffic.
22. Subject to the provisions of paragraphs 29 and 35 (a) and (c) of this Schedule, flying machines shall always give way to gliders and to balloons, fixed or free, and to airships, and airships shall always give way to gliders and to balloons, whether fixed or free.
23. An airship which is under way and which is not under control or which has voluntarily stopped its engines shall, for the purposes of the provisions of this Section of this Schedule, be classed as a free balloon.
24. (1) When circumstances permit, an aircraft can ascertain risk of collision with another aircraft by carefully watching the successive compass bearings and angles of elevation of the other aircraft and it shall consider that risk of collision with the other aircraft exists if neither the bearing nor the angle of elevation changes appreciably and if the distance between the two aircraft diminishes.
(2) The term "risk of collision" includes all risk of accident due to undue proximity of other aircraft.
25. Every aircraft which is required by the rules contained in paragraphs 22, 23 and 24 of this Schedule to give way to another aircraft to avoid collision, shall keep at a safe distance, having regard to the circumstances of the case.
26. While observing the provisions relative to risk of collision contained in paragraphs 24 and 25 of this Schedule, a mechanically- driven aircraft must always manoeuvre according to the rules contained in paragraphs 27, 28, 29, 30 and 31 of this Schedule as soon as it is apparent that, if it pursued its course, it would not pass clear of another aircraft.
27. When two mechanically-driven aircraft are meeting end on or nearly end on, each shall, without prejudice to the application of the provisions of paragraph 22 of this Schedule, alter its course to the right.
28. Subject to the application of the provisions of paragraphs 22 and 35 (c) of this Schedule, when two mechanically-driven aircraft are on courses which cross, the aircraft which has the other on its own right side shall keep out of the way of the other.
29. An aircraft overtaking another aircraft shall keep out of the way of the overtaken aircraft by altering its own course to the right, and must not pass by diving.
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