Wind Direction Indicators During takeoffs and landings, pilots need to know which runway to use. At a controlled airport, there are various methods of obtaining the current airport information, including the “active runway”, or runway in use. At an uncontrolled airport, pilots may be the one to determine which runway to use, depending on the type of services available. In many cases, the decision will be based on what you see when looking at a wind direction indicator. There are two types of direction indicators usually located near the runway. The most common is the wind sock, which is used at both controlled and uncontrolled airports. Although a wind sock may not be the initial source of wind information at a controlled airport, there will still be a wind sock positioned near the runway. It will tell pilots the wind conditions near the touchdown zone of the runway. In gusty conditions, the wind sock moves back and forth. Also, the stronger the wind is, the straighter the extension of the wind sock becomes. The other type of wind direction indicator is a wind tee. The tail of the wind tee aligns itself like a weather vane into the wind. However, it does not indicate wind intensity or gusty conditions. In some cases, a wind sock and tee may be at the same location. If so, the tee may be manually aligned to show which runway is active. A tetrahedron (四面体) is a landing direction indicator, usually located near a wind direction indicator. It may swing freely, as the wind sock does, or it may be manually positioned to show the direction of landing. (267 words) 10