Figure 4-15 -- Runway wave-off lights.
MISCELLANEOUS AIRFIELD EQUIPMENT AND EMERGENCY
There are a number of other systems and pieces of equipment that you should be
aware of as an air traffic controller.
Wind cones (socks) are often located at a central position on the airfield and in the
vicinity of helipads. They provide pilots with visual information of surface wind direction
and general indication of wind speed. This information is most useful during takeoff, for
orientation to make an approach, and in the final phase of approach prior to touchdown.
Air passing through the wind cone aligns the wind cone with the wind to indicate the
direction the wind is blowing. The wind cone has an advantage over the wind tee
because in addition to indicating wind direction, it also gives an approximation of wind
The velocity of the surface wind can be approximated by comparing the angle of the
wind cone in its relation to the ground. The wind cone will stand out parallel with the
ground when the wind is 15 to 20 knots. Since the wind cone stands out parallel to the
ground with a steady wind greater than 20 knots, the pilot must exercise caution when
the wind cone is their only available reference. A gusty wind is indicated when the wind
cone alternately rises and falls rapidly. When the wind cone hangs limply at the mast, a
calm wind is indicated. Should the wind cone swing from side to side and rise and fall,
gusty, shifting wind is indicated.
The wind cone may be orange or white. Standard wind indicator is the 12 foot wind
cone often called the windsock. An 8 foot cone may be approved for use on small
secondary airfields, helipads or if necessary to locate the wind indicator closer than
standard to the runway. If night flight operations are conducted, the wind cone shall be