Runway

A runway is a strip of land on an airport, on which aircraft can take off and land. Runways may be a prepared surface, (often asphalt or concrete) or an unprepared surface (grass, dirt, gravel).

Runway lighting

The runway threshold is marked by a line of green lights. The sides of the runway are marked by lines of bright white lights. Larger runways may have another line of dimmer white lights running down the centerline. According to Transport Canada's regulations, the runway-edge lights must be visible for at least 2 miles.

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The lights must be arranged such that:

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• the minimum distance between lines is 75 feet, and maximum is 200 feet;
• the maximum distance between lights within each line is 200 feet;
• the minimum length of parallel lines is 1400 feet;
• the minimum number of lights in the line is 8.

Some airports/airfields (particularly uncontrolled ones) are equipped with Pilot Controlled Lighting, so that pilots can temporarily turn on the lights when they need them. This avoids the need for automatic systems or staff to turn the lights on at night or in other low visibility situations. This also avoids the costs of having hundreds of lights on for extended periods.

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