Windsock size guide
Choosing the right windsock size. Visibility, regulation, and site specifics.
Falcon Premium Windsocks are available in 4FT (1.2m), 7FT (2.1m), and 12FT (3.7m). This guide explains which size suits which application, what regulations prescribe, and how to assess your site.
Quick Reference Table
At a glance
| Size | Length | Typical visibility | Best suited to |
|---|---|---|---|
| 4FT | 1.2 metres | Short to moderate range | Helipads, small airfields, microlight fields, parachute schools, industrial sites, construction sites |
| 7FT | 2.1 metres | Moderate to long range | Commercial airfields, licensed aerodromes, larger helipads, most CAA-inspected sites |
| 12FT | 3.7 metres | Long range | Large airports, major industrial complexes, sites specified for maximum-visibility indication |
4FT Windsock Section
4FT (1.2m) — The most popular size
The 4FT windsock is the highest-volume size by a significant margin. It suits:
- Helipads (hospital, corporate, offshore)
- Grass airstrips and unlicensed airfields
- Microlight and light aircraft clubs
- Parachute and skydiving schools
- Industrial sites with moderate visibility requirements
- Construction sites and temporary installations
- Marine and watersport applications
At 1.2 metres, the 4FT is clearly visible from the immediate site area. It does not provide long-range visibility from hundreds of metres away. If your site needs wind direction indication that can be seen from the far side of a large airfield, size up.
Pricing: Snap-On from GBP 70. Lace-On from GBP 60.
7FT Windsock Section
7FT (2.1m) — The standard aviation specification
The 7FT windsock is the standard specification for most CAA-inspected aerodromes and commercial aviation sites. It suits:
- Commercial airfields and regional airports
- Licensed UK aerodromes (check your specific CAP 168 requirement)
- Larger helipads, particularly those with higher movement rates
- Industrial sites specified for greater visibility
- Larger parachute operations
At 2.1 metres, the 7FT provides good visibility across a standard airfield and is the default size specified by many aviation inspectors. If you are specifying a replacement at a commercial aviation site, 7FT is the most common size.
Pricing: Snap-On from GBP 100. Lace-On from GBP 90.
12FT Windsock Section
12FT (3.7m) — Maximum visibility
The 12FT windsock provides the maximum visibility of the Falcon Premium range. It suits:
- Large airports and international aerodromes
- Major industrial complexes
- Sites where the windsock must be visible from long range
- Specifications that mandate large-format wind direction indication
At 3.7 metres, the 12FT is a substantial installation. It requires a correspondingly sturdy swivel arm and mounting arrangement. It is less common than the 4FT and 7FT but essential where specified.
Pricing: Snap-On from GBP 130. Lace-On from GBP 120.
What regulations prescribe
Different standards prescribe different windsock sizes for different applications. Check your applicable regulation.
CAA CAP 168 (UK aerodromes): Specifies a minimum length and truncated conical shape. Most UK licensed aerodromes use 7FT; smaller sites may use 4FT. Large sites may specify 12FT. Check your aerodrome manual for the specific requirement.
ICAO Annex 14 (International aerodromes): Specifies truncated cone shape, minimum length of 3.6 metres at international aerodromes (effectively 12FT). Smaller aerodromes may operate to different specifications.
FAA AC 150/5345-27F (US airports): Specifies three sizes by airport category: - Size 1 (small airports, restricted visibility): 8FT (2.4m) fabric length - Size 2 (most US public airports): 12FT (3.7m) fabric length - Size 3 (large airports): 12FT (3.7m) fabric length The Falcon Premium 12FT serves FAA Size 2 and Size 3 specifications.
Industrial sites: Industrial regulations (COMAH, OSHA PSM, DSEAR) do not prescribe windsock size. The site safety assessment should specify the requirement based on site layout and visibility needs.
Practical considerations
Visibility: Stand at the furthest point where the windsock needs to be visible. Can someone there read the wind direction from a 4FT windsock at eye level? If not, size up.
Height of installation: A windsock mounted at height needs to be larger than one mounted at ground level to achieve the same apparent size.
Site scale: Small helipad or microlight field: 4FT. Commercial airfield: 7FT. Large airport: 12FT. When in doubt, look at what is currently installed at comparable sites.
Regulatory requirement: If your site is subject to a specific standard, follow the standard. Most sites are not tightly prescriptive on size as long as it meets the standard's minimum.
Wind conditions: Very high wind sites may benefit from a larger size for improved readability under full deflection.
Replacing an existing windsock
If you are replacing an existing windsock, the simplest approach is to order the same size. Check the installed windsock or the previous order record.
If the existing windsock is being replaced because it does not meet your requirement (not because of wear), consider upgrading. The 4FT to 7FT step improves visibility significantly for most airfield applications.
Attachment type must match your swivel arm or cage. If unsure, read our snap-on vs lace-on comparison guide or contact us with a photo of your existing mounting.
FAQ
Q: What size windsock does my airfield need? A: Most UK licensed aerodromes specify 7FT. Smaller airfields, helipads, and grass strips typically use 4FT. Large commercial airports may specify 12FT. Check your CAP 168 aerodrome manual for the exact requirement.
Q: What is the difference between 4FT and 7FT? A: The 7FT is 75% longer than the 4FT (2.1m vs 1.2m) and provides significantly greater visibility. The 4FT is more cost-effective and suits smaller sites. The 7FT is the standard for most commercial aviation applications.
Q: Is a 12FT windsock overkill for my site? A: Probably, unless your site specifies it. 12FT is for major airports, large industrial complexes, and sites where long-range visibility is essential. Most sites use 4FT or 7FT.
Q: Can I use a 4FT windsock for aviation compliance? A: Yes, provided your CAP 168 aerodrome manual or FAA standard allows it. Small airfields, helipads, and grass strips commonly use 4FT within compliance requirements. Check your specific regulation.
Q: How is the windsock length measured? A: The stated length (4FT, 7FT, 12FT) refers to the fabric length from mouth to tip, excluding the harness.