Aerodrome Lighting — Page 426, Lesson 572

I want to walk you through the aerodrome lighting chapter now, starting with the beacons and then moving into approach lighting systems. First, let's talk about aeronautical beacons. Where it's operationally necessary, an aerodrome beacon or an identification beacon must be provided if the aerodrome is intended for use at night. Now, the need for a beacon isn't automatic — it's determined by looking at three things: the requirements of the air traffic using the aerodrome, how conspicuous the aerodrome features are against their surroundings, and whether other visual and non-visual aids are already installed that help in locating the aerodrome. Let me be precise about the two types. The aerodrome beacon shows flashes of light. For land aerodromes, the colours are white, or white and green. For water aerodromes, the colours are white, or white and yellow. A beacon must be provided at an aerodrome intended for night use if one or more of these conditions exist: aircraft navigate predominantly by visual means; reduced visibilities are frequent; or it's difficult to locate the aerodrome from the air because of surrounding lights or terrain. Now the identification beacon. This one is provided at an aerodrome intended for night use that cannot be easily identified from the air by any other means. The identification beacon shows the Morse code identification of the aerodrome — and here's the colour coding: flashing green at a land aerodrome, flashing red at a UK military aerodrome, and flashing yellow at a water aerodrome. Now let's move to approach lighting systems. These are patterns of fixed lights of variable intensity, showing white, designed to give the pilot guidance to the threshold — or aiming point — of a runway, in poor visibility or at night. The light patterns may include distance coding, and they give an indication of aircraft attitude. The arrangement may also give an indication of aircraft height above the approach — that sentence cuts off in the source, but the key idea is that these lights are your visual reference for aligning with the runway and judging your descent path when you can't see the runway clearly. Let me show you what a simple approach lighting system looks like. And here's the more complex CAT I Calvert system with its five bars and centre line. So to tie it together: the beacons help you find the aerodrome from a distance at night, and the approach lighting takes over to guide you visually right down to the runway threshold. The beacon tells you where the aerodrome is; the approach lights tell you where the runway is and how you're positioned relative to it.