Curved Lighting 1959.jpg

ENGINEERING October 2, 1959

‘Curved’ Lighting at Hong Kong Airport

Mountainous country and shortage of land made the construction of Hong Kong’s new airport difficult. A unique lighting system permits 24 hour operation, even in bad visibility.

Hong Kong’s new Kai Tak Airport has been designed to be operational 24 hours a day, even in bad visibility, which was impossible on the old site, owing to limited radio and visual aids. Since land is at a premium, the new runway, 8,340 ft long, has been built on an artificial promontory, 795 ft wide, jutting into the sea from Kowloon. This involved the moving of over 20 million tons of soil and the paving of some 60 acres of runway and taxi tracks, all to a strength sufficient for aircraft of up to 400,000 lb all-up weight. The airport is being equipped with all the latest ground-to-air aids, including long range surveillance radar, short range approach radar, and instrument landing equipment.

The approach and runway lighting, supplied by the General Electric Company Limited, London, WC2, and installed by their associate, the British General Electric Company Limited, Hong Kong, was designed by Preece, Cardew and Rider, London, in conjunction with the Hong Kong Department of Civil Aviation. Both approaches and the runway are equipped with a dual system of lighting, low intensity for normal conditions and high intensity for bad visibility. The civil consultants were Scott and Wilson, Kirkpatrick and Partners (Hong Kong).

To the north west, nearby hills prevent a normal direct approach to runway 13, and aircraft have therefore to follow a curved line of approach lights, the only one of its kind in the world. This approach passes over a densely populated part of Kowloon city, and in places the lights have had to be mounted on structures spanning buildings and streets.

Aircraft approaching from the west start their let-down procedure over the West Lamma Channel, and make a right hand turn over Kowloon to land on runway 13. To help pilots align their aircraft on the correct approach flight path, a green flashing beacon has been erected on a hill near Tai Hang Tung, about 4,000 ft from the beginning of the north west approach lighting system.

This system consists of a 3,510 ft line curving on an arc of a circle designed to conform to a ‘rate one turn’ of an aircraft flying at 140 knots (that is, a turn in which the aircraft changes course at a rate of 3° per sec.). The approach is then straight and in line with the runway centre line for the remaining 2,800 ft to the threshold bar. Lights are spaced 438 ft apart on the curved section of the approach and 200 ft apart on the remainder. Crossbars of lights at the start (No. 4) and finish (No. 3) of the curved section and at 2,000 ft (No. 2) and 1,000 ft (No. 1) from the threshold help the pilot to judge the horizontal position of his aircraft and, since the final three bars decrease in width towards the runway, also give a rough indication of height.

On the curved section of the approach the high intensity lights, which have a limited horizontal beam spread, have been duplicated and angled so that they present a complete lighting pattern to a pilot passing over the location beacon. Thus, on the initial approach, from the location beacon to crossbar 4, the pilot sees a complete pattern from one set of lights, and then along the curve he sees it from the second set. To assist in the transition from one set of lights to the other the beams have been arranged to overlap.

As the end of runway 13 is close to Kowloon city the approach clearances are necessarily high, and the lights have had to be mounted on the roofs of buildings or on special structures erected for the purpose. Each of the high and low intensity patterns is connected on individual duplicate series circuits fed from separate supply sources, and are “ interleaved,” so that each circuit feeds alternate lights. Failure of one supply source therefore leaves the pattern in operation, but with alternate lights only.

The runway has a dual system of high and low intensity lights spaced at 200 ft intervals, and circuited in the same way as the approach lights, so that failure of one circuit only cuts out alternate lights. Elevated type lights are used, except at taxi track intersections, when inset fittings are installed. The runway lighting is white, except for the last 2,000 ft facing the approach, where yellow filters have been fitted; the two colours give an indication of range. A threshold bar of green inset lights, with wing bars of high intensity white lights for bad visibility, marks each end of the runway.

Aircraft approaching from the east fly through the Lei Mun gap, which bears directly on runway 31, and the lighting consists of a 2,000 ft line of high and low intensity fittings on piles driven into the sea bed at 200 ft spacing. Both systems are “ interleaved ” from separate circuits.

In poor visibility extra assistance is given to pilots by two high intensity angle of approach indicators, giving a flashing light divided into three horizontal coloured zones—red for too low, amber for too high, and green for correct approach height.

Both approach systems have high intensity lights to form lead out patterns for take off. The low intensity approach lights are omnidirectional, and can be used as lead-out lights as well.

All the lighting is fed through two substations, taking current at 6,600 V, 3 phase 50 cycles and sending out a 346/200 V, 3 phase, 4 wire supply. Control is from a console in the control tower, which has a mimic diagram. Provision of the lighting system has required 675 lighting fittings of various types, 120 core miles of power cable, 100 core miles of control cable, and the making of more than 3,000 cable joints.

Hi Daniel,

I hadn't seen that article before, and as it will be useful I converted your image to a text version to make it easier to read. Thanks for posting it.

Regards, David