Wind direction indicators

General (ICAO)

ICAO Annex 14 Vol I, §5.1.1 mandates: Every aerodrome shall have at least one wind direction indicator.

Requirements (§5.1.1.2):

• Visible to aircraft in flight, during taxi and on the apron.
• Located clear of obstructions causing wind disturbance.
• Illuminated if the aerodrome is used for night operations.

Construction (§5.1.1.3):

• Truncated cone of fabric (windsock, "wind cone").
• Length at least 3.6 m, mouth diameter at least 0.9 m.
• Material such that the sock clearly shows direction; fully horizontal at ≥ 15 kt (28 km/h).

Location: often on the signal square, but not mandatory there; some aerodromes have multiple windsocks at runway ends.

White-circle marking: a 15 m diameter white circle around the windsock marks its location (visible especially on grass strips).

Colour: orange/white striped or solid orange (selectable).

Other wind direction indicators:

• Landing direction indicator "T": white or orange "T" with cross bar — the longitudinal axis indicates the landing/take-off direction. On the signal area.
• Tetrahedron: three-sided pyramidal object; the apex points in landing direction.

Europe (EASA / EU)

Applied via Regulation (EU) 139/2014 (Part-ADR) and CS-ADR-DSN Subpart M. Minimum requirements identical with ICAO Annex 14.

Germany (national)

EU law. On German aerodromes the windsock is the standard device; landing-direction "T" and tetrahedron are rare. Illumination is required for aerodromes approved for night operations (AIP Germany VFR section per aerodrome).