How is a windsock lit from outside?
Floodlights above the cone, aimed down at it, light its outside, so the pilot can read wind direction and strength after dark.
An externally illuminated windsock is an ordinary fabric cone on a swivel that is lit by floodlights outside it. In the arrangement shown, the lights are mounted on top of the mast, above the cone, and aimed down at it (some makes and sites use floodlights on the mast or a separate pole instead, with the same rule: keep the beam on the cone), so the fabric is seen by reflected light, as it is by day. Nothing is fitted inside the turning cone, so there is no lamp and no feed to look after in the cone itself.
The cone swings round the mast with the wind, so the beams have to cover the whole arc it can move through, and several floodlights are often used for that. The aim is the critical part: the beams are pointed down at the cone and shielded, because light that spills toward the approach can dazzle pilots, and light that misses the cone is wasted. At each visit check the floodlights, the aim, the lenses and the cone. The internally illuminated windsock puts the lamp inside the cone instead.
Frequently Asked Questions
Q1What is an externally illuminated windsock?
A windsock lit by floodlights outside the cone. The lights shine on the fabric, so the cone is seen by reflected light at night, much as it is by day.
Q2How does it differ from an internally illuminated windsock?
An internally illuminated windsock has a lamp inside the cone, so the fabric glows from within. An externally illuminated one has no lamp or feed inside the turning cone, but its floodlights have to be aimed correctly.
Q3Why does the aiming matter?
The whole cone must be lit through its swing, but light that spills toward approaching pilots can dazzle them, and light that misses the cone is wasted. The floodlights sit above the cone and are aimed down at it, with shielding so the beams stay on the cone.
Q4Why are there usually several floodlights?
The cone swings round the mast with the wind, and a single light could leave one side dark. Several units spaced round the top of the mast help keep the cone lit whichever way it points. The number and position depend on the make and site.
Q5What should be checked on an externally illuminated windsock?
That every floodlight works; that the aim has not shifted; that the lenses are clean; that the cone is lit through its whole swing; that the fabric is clean and the cone turns freely; and that the cable and connections are sound. Isolate the supply before working at the mast.
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