Windsock

Alternating stripes of high-visibility orange and white were initially used to help estimate wind speed, with each stripe extended adding 3 knots (5.6km/h; 3.5mph) to the estimated speed. Some circular frame mountings cause windsocks to be held open at one end and the first stripe extended, indicating a velocity of 3 knots even when stripes are not present. A fully extended windsock suggests a wind speed of or greater. Standards Per FAA standards, a properly functioning windsock orients itself to a breeze of at least and fully extends in a wind of . ICAO standards specify a truncated cone-shaped windsock at least long and in diameter at the large end. It should be readable from an altitude of and ideally be of a single colour. If it is necessary to use two colours, they should ideally be orange and white, arranged in five alternating bands, with the first and last darker in tone. In wind speeds of or more, they must indicate wind direction to within ±5°. == Other related wind direction indicators ==

Wind tees and wind tetrahedrons are two other commonly used wind direction indicators in airports. Wind tees are shaped like an airplane so that they match with the heading of an aircraft ready to take off and land. Wind tetrahedrons always have their pointed ends pointing to the wind. Wind tees and tetrahedrons can swing freely and align themselves with the wind direction, but neither provides an indication of wind speed, unlike a windsock. Since a wind tee or tetrahedron can also be manually set to align with the runway in use, a pilot should also look at the wind sock for wind information, if one is available. ==See also==