It is important for a pilot to know the direction of the wind. At facilities with an operating control tower, this information is provided by ATC. Wind information may also be provided by FSS personnel located at a particular airport or remotely through a Remote Communications Outlet (RCO). At airports equipped to receive and broadcast on a Common Traffic Advisory Frequency (CTAF), pilots may also request wind information on that frequency.
When none of these services is available, it is possible to determine the wind direction and the runway in use by observing visual wind indicators. A pilot should still check these wind indicators, even when wind information is provided on the CTAF, because there is no assurance that the reported information is accurate.
The wind direction indicator can be a wind cone, wind sock, tetrahedron, or wind tee. These are usually located in a central location near the runway and may be placed in the center of a segmented circle, which identifies the traffic pattern direction if it is other than the standard left-hand pattern. [Figures 1 and 2]
 |
| Figure 1. Wind direction indicators |
 |
| Figure 2. Segmented circle |
The wind sock is a good source of information since it not only indicates wind direction but allows the pilot to estimate the wind velocity and/or gust factor. The wind sock extends farther in stronger winds and tends to move back and forth when the wind is gusting. Wind tees and tetrahedrons can swing freely and align themselves with the wind direction. 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.