The orange airport wind cone is a simple yet effective tool used by pilots at nearly every airport in the world. Using only a fabric cone, or "sock," pilots can determine both wind direction and an approximate wind speed. The Federal Aviation Administration (FAA) creates strict standards for the construction and placement of airport windsocks. These standard specifications are maintained in Advisory Circular (AC) 150/5345-27D. International standards vary from U.S. FAA requirements.
There are two main types of windsocks, the L-806 and L-807. The type depends on how the sock is mounted, but their assemblies are similar. Depending on type, the windsock must be either 8 feet in length and 18 inches in diameter, or 12 feet long and 36 inches in diameter. Depending on the type, the windsock is mounted on a pole that is typically 10 to 16 feet high.
The windsock must work in ambient conditions between minus 19.4 degrees C and 55 degrees Celsius. The windsock must be able to withstand wind speeds of up to 75 knots (86mph). The windsock must move freely when subjected to winds greater than 3 knots (3.5mph) and must indicate true wind direction +/- 5 degrees. The windsock must extend fully when the wind reaches 15 knots (17mph).
There are two types of lighting systems for windsocks. Style I-A uses an external lighting system with lights mounted either on the ground or above the windsock, and must provide at least 2 foot-candles (21.5 lux) of illumination on the extended sock. Style I-B uses an internal lighting system. It must feature at least two separate lamp bulbs so the windsock is still useful at night in the event of a single burnt bulb. In certain cases, windsocks may be unlit at airports only used during daytime hours. Lighting must be aimed to reduce glare for pilots.
Colour and Markings
The fabric for the windsock must be made of cotton, a synthetic material or a blend of the two. The fabric must be waterproof or water repellent. The colour of the windsock must be white, yellow or orange, although white is uncommon. All exposed metal parts must receive a primer, a body and a finish coat of paint. The final coat of paint must be orange. Ground markings referencing the cardinal directions (North, East, South, West) and 30-degree increments must be painted on the ground for reference.
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