How to Determine Speed of Wind Sock

HOW DOES A WINDSOCK WORK?

If an aircraft is about to take off and the pilot wants to get a rough idea about the wind speed and its direction then it could be done through a conical shaped textile tube, which is known as a windsock. Windsock is normally placed next to the runway which could be easily accessed by the pilot during take-off. Windsocks also find a place in most airport ground charts, where it is represented by a little conical symbol.

Operation of Windsock:

There are lamps which are installed into the windsock to make it visible for operating efficiently during the night. There are some rudder inputs which are required for overcoming the effect of wind during take-off. The rudder is a movable part of the vertical stabilizer, which could be deflected for left-right movement of the aircraft.

So the windsock could be used to get a rough estimate about the amount of rudder deflection required so that aircraft always remain in-line with the runway during take-off.

Finding out the wind direction:

To find out the wind direction, the pilot firstly takes a look at the compass to check his heading direction and then windsock is used to estimate the pointing angle of wind direction. Windsock would get deflected in the direction opposite to where the wind is coming from. If the windsock is pointing towards the east, then it means that the wind is blowing from west to east direction.

Wind blowing from the west is given a heading notation of 270 ⁰. So the pilot could refer to the windsock to calculate the relative wind direction by taking a note of the values of the compass and estimated direction given by Windsock.

Finding out the wind speed:

There are different rings present on the windsock. These are mainly colored alternately with red and white. Each ring indicates the wind velocity of 5 knots (9.26 km/hr). A wind speed of 15 knots would be indicated by three fully blown rings. If all the rings are fully blown up, then one could even expect some gusts. In this way, the pilot could multiply the number of fully blown rings with 5 to get an estimated wind speed in Knots.

Windsock is just used for getting a rough idea. Windsocks provide quick information about wind speed and its direction. Windsocks are easy to maintain and install. Flight regulations ensure that even the smallest airport should have at least one windsock.

To get the exact information about wind and weather ATIS (Automatic Terminal Information Service) is used. ATIS is a recorded broadcast of aeronautical information which includes weather conditions and several other things. ATIS is very useful to reduce the workload of ATC (Air Traffic Controller). ATIS works at a particular frequency which would be mentioned by the airport. The pilot would have to tune in the radio at that particular frequency to hear the recorded voice.

Therefore it could be concluded that the pilot must refer to the ATIS to get the exact information about the weather. Windsocks could only be used to provide a rough estimate of the wind information.

How to Determine Speed of Wind Sock

Source: https://www.aircraftnerds.com/2018/08/how-does-windsock-work.html