The Rules of the Air Regulations 1996

Signals visible from the ground

45.—(1) A black ball 60 centimetres in diameter suspended from a mast signifies that the directions of take off and landing are not necessarily the same.

(2) A checkered flag or board, 1.2 metres by 90 centimetres containing twelve equal squares, 4 horizontally and 3 vertically, coloured red and yellow alternately, signifies that aircraft may move on the manoeuvring area and apron only in accordance with the permission of the air traffic control unit at the aerodrome.

(3) Two red balls 60 centimetres in diameter, disposed vertically one above the other, 60 centimetres apart and suspended from a mast, signify that glider flying is in progress at the aerodrome.

(4) Black arabic numerals in two-figure groups and, where parallel runways are provided the letter or letters L (left), LC (left centre), C (centre), RC (right centre) and R (right), placed against a yellow background, indicate the direction for take off or the runway in use.

(5) A black letter C against a yellow background, as illustrated in this paragraph,

Fig. 19

indicates the position at which a pilot can report to the air traffic control unit or to the person in charge of the aerodrome.

(6) A rectangular green flag of not less than 60 centimetres square and not more than 66 centimetres square flown from a mast indicates that a right-hand circuit is in force.