Windsock Compliance Standards: CAA, FAA, ICAO and What Your Auditor Expects

Six regulatory frameworks govern windsock specification across aviation and industrial sites worldwide. CAA CAP 168 in the UK. FAA AC 150/5345-27F in the United States. ICAO Annex 14 internationally. EASA EU Regulation 139/2014 across the European Union. COMAH and HSE guidance for UK industrial sites. OSHA 29 CFR 1910.119 for US process safety facilities.

No single resource has covered all six in one place. Until now.

This guide explains what each standard requires, how they relate to each other, where they differ, and what your auditor expects to see in the documentation file. It is written for procurement managers, health and safety officers, and aviation operations teams who need to verify that a windsock meets their specific regulatory requirement before raising a purchase order.

If you are replacing an existing windsock, preparing for an inspection, or specifying a new installation, this is the reference you need.

UK Aviation: CAA CAP 168

CAA CAP 168 (Licensing of Aerodromes) is the UK Civil Aviation Authority's standard for aerodrome design and operations. Chapter 7 covers visual aids, including wind direction indicators.

CAP 168 does not define its own windsock specification from scratch. Instead, it references ICAO Annex 14 as the baseline and adds UK-specific requirements for licensed aerodromes.

Key requirements under CAP 168:

• At least one wind direction indicator shall be provided at every licensed aerodrome
• The indicator must be visible from aircraft in flight or on the movement area
• Colour shall contrast with the background against which it is viewed. Fluorescent orange to EN471 is the accepted standard
• The windsock must extend fully in a wind of 15 knots and indicate wind direction within plus or minus 5 degrees at 3 knots
• Night operations require the windsock to be illuminated, either internally or externally
• Supplementary wind indicators may be required for aerodromes with multiple runway configurations

Who is inspected against CAP 168: All UK-licensed aerodromes. CAA inspectors verify wind direction indicator compliance as part of the aerodrome licensing audit.

What the Falcon Premium meets: The Falcon Premium Windsock is compliant with CAA CAP 168. It is manufactured from 200 GSM PU coated polyester, specified to EN471:2003 fluorescent orange, and designed to extend fully at 15 knots. Certificates of Conformity referencing CAA CAP 168 are issued with every order.

US Aviation: FAA AC 150/5345-27F

FAA Advisory Circular AC 150/5345-27F (Specification for Wind Cone Assemblies, December 2021) is the current US federal standard. It replaced the earlier 27D and 27E revisions.

This is the most detailed of the aviation standards. It specifies not only the windsock itself, but the supporting structure, lighting, and qualification testing.

Key requirements under FAA AC 150/5345-27F:

• Dimensions: Size 1 windsocks must be 8 feet (2.5 m) in length with an 18-inch (0.45 m) throat diameter. Size 2 must be 12 feet (3.75 m) with a 36-inch (0.9 m) throat diameter
• Extension: The windsock must fully extend in a wind of 15 knots (28 km/h)
• Direction accuracy: Must indicate true wind direction within plus or minus 5 degrees at wind speeds of 3 knots or above
• Fabric: Must have a minimum breaking strength of 150 pounds (667 N) in both warp and filling directions. May be cotton, synthetic, or blended. Must be water repellent if not naturally immune. Colour may be white, yellow, or orange, as specified by the purchaser
• Temperature tolerance: Must operate between minus 67 degrees F (minus 55 degrees C) and 131 degrees F (plus 55 degrees C)
• Wind tolerance: Must withstand wind speeds up to 75 knots (140 km/h)
• Lighting: Externally lit wind cones (Style I-A) require a minimum of 2 foot-candles illumination across the full rotation. Internally lit (Style I-B) require average luminance of 10 to 30 foot-lamberts on top and lateral surfaces
• Supporting structures: Type L-806 (low-mass, frangible) and Type L-807 (rigid, hinged) are defined with specific moment load requirements
• Qualification: Equipment must be tested and certified under the FAA Airport Lighting Equipment Certification Program (AC 150/5345-53)

Important note on the current version: The content brief for this article references AC 150/5345-27F (December 2021) as the current revision. If you are specifying for a federally funded airport project in the United States, confirm you are referencing the latest revision, as compliance with the current AC is mandatory for grant-funded work.

Who is inspected against this standard: All Part 139 certificated airports in the United States. FAA inspectors include wind indicators in the Airport Certification Safety Inspection (ACSI) checklist.

What the Falcon Premium meets: The Falcon Premium Windsock is compliant with FAA requirements for fabric specification, extension at 15 knots, direction accuracy, and water repellence. Certificates of Conformity referencing FAA compliance are issued with every order.

International Aviation: ICAO Annex 14

ICAO Annex 14 (Aerodromes, Volume I: Aerodrome Design and Operations) is the international baseline. Published by the International Civil Aviation Organization, it sets the minimum Standards and Recommended Practices (SARPs) that all 193 ICAO member states are expected to adopt.

ICAO Annex 14 is the foundation upon which CAA CAP 168, EASA regulations, and many other national standards are built. Understanding it helps you understand why the UK, EU, and many other national standards share common requirements.

Key requirements under ICAO Annex 14:

• At least one wind direction indicator shall be provided at an aerodrome
• It shall be located so as to be visible from aircraft in flight or on the movement area, and not affected by disturbed airflow from nearby objects
• The indicator shall indicate the direction and approximate speed of the surface wind
• The windsock shall be in the form of a truncated cone made of fabric, not less than 3.6 m (12 ft) in length, with a mouth diameter of at least 0.9 m (36 in) at the larger end
• It must extend fully in a wind of 15 knots and indicate wind direction at a wind speed of 3 knots
• Colour shall be chosen to contrast with the background. A single colour (preferably white or orange) or two contrasting colours (orange and white, or red and white) in five alternating bands are recommended
• The indicator shall be illuminated if the aerodrome is intended for use at night

Relationship to national standards: ICAO Annex 14 allows member states to file "differences" where their national requirements diverge from the SARPs. Both the UK (via CAA CAP 168) and the US (via FAA AC 150/5345-27F) have adopted ICAO Annex 14 with local additions. When a national standard exists, it takes precedence over ICAO Annex 14 within that territory.

What the Falcon Premium meets: The Falcon Premium Windsock is compliant with ICAO Annex 14 requirements for wind direction indicators. This is particularly relevant for international airport projects, military installations outside the US and UK, and export orders where the buyer specifies ICAO compliance.

EU Aviation: EASA EU Regulation 139/2014

EASA (European Union Aviation Safety Agency) Commission Regulation (EU) No 139/2014 establishes the requirements for aerodromes and aerodrome oversight across EU member states. It largely aligns with ICAO Annex 14 but adds EU-specific oversight and certification structures.

Key points:

• EASA Regulation 139/2014 requires certificated aerodromes to provide wind direction indicators as defined in ICAO Annex 14 and the associated EASA Certification Specifications (CS-ADR-DSN)
• The Certification Specifications reference ICAO Annex 14 directly for wind indicator dimensions, performance, colour, and illumination requirements
• EU member states may add national requirements. For example, Germany's national aviation authority (LBA) and France's DGAC may impose additional local provisions
• Post-Brexit, the UK is no longer subject to EASA regulation. UK-based operations follow CAA CAP 168 exclusively

Practical impact: For buyers specifying windsocks for EU aerodromes, the ICAO Annex 14 specifications apply through the EASA framework. The physical requirements for the windsock (dimensions, extension, colour, illumination) are effectively the same as ICAO Annex 14. The difference is in the certification and oversight structure, not the product specification.

What the Falcon Premium meets: Compliant with the ICAO Annex 14 requirements referenced by EASA Regulation 139/2014.

UK Industrial: COMAH and HSE Guidance

COMAH (Control of Major Accident Hazards) Regulations 2015 apply to sites in the UK that store or process hazardous substances above specified thresholds. The HSE (Health and Safety Executive) and the Environment Agency jointly enforce COMAH.

Wind direction indicators are a key component of COMAH site safety reports and emergency response planning.

Key requirements:

• COMAH upper-tier sites must include meteorological monitoring in their safety reports. Wind direction and wind speed data inform toxic plume dispersion modelling, emergency evacuation routing, and fire service tactical planning
• HSE guidance expects wind direction indicators to be permanently installed, continuously visible, and maintained to a standard that ensures reliability during an emergency
• For upper-tier COMAH sites handling highly toxic or flammable substances, the HSE may expect a higher specification windsock than the standard aviation grade. This typically means heavier fabric (400 GSM chlorosulfonated polyethylene or equivalent), marine-grade stainless steel hardware, and greater resistance to chemical exposure
• Wind rose data for the site must be documented in the safety report. The wind direction indicator is a visible, real-time complement to this data
• Lower-tier COMAH sites have reduced reporting obligations, but wind direction indication remains a common requirement in the emergency response plan

What "COMAH compliant" actually means for windsocks:

There is no single COMAH windsock specification in the way that CAA CAP 168 or FAA AC 150/5345-27F defines aviation windsock requirements. COMAH compliance is assessed holistically as part of the site safety report. The HSE assesses whether the wind direction indicator is appropriate for the hazards present on site.

In practice, upper-tier COMAH sites (particularly those with toxic release or flammable atmosphere risks) require a heavy-duty specification. The heavier fabric, stainless steel construction, and chemical resistance of a 400 GSM chlorosulfonated polyethylene windsock are what inspectors expect to see at these facilities.

Falcon and COMAH:

The Falcon Premium Windsock (200 GSM PU coated polyester) is compliant with aviation standards (CAA, FAA, ICAO) and is used across a range of industrial applications. For sites requiring wind direction indication as part of COMAH compliance, the published specifications on the product page allow you to verify the product meets your site safety assessment requirements.

Falcon also manufactures a Heavy Duty specification using chlorosulfonated polyethylene fabric for environments requiring additional chemical resistance. Contact us for details on the Heavy Duty range.

US Industrial: OSHA 29 CFR 1910.119

OSHA (Occupational Safety and Health Administration) Standard 29 CFR 1910.119 (Process Safety Management of Highly Hazardous Chemicals) is the US equivalent of COMAH for process safety. It applies to facilities that handle, use, or store highly hazardous chemicals above threshold quantities.

Key points:

• OSHA 29 CFR 1910.119 requires employers to develop and implement a process safety management programme. Emergency planning is a core element
• Wind direction indicators are commonly required as part of emergency response planning, particularly for facilities where toxic gas release or vapour cloud formation is a credible hazard scenario
• OSHA does not specify a windsock standard by code number. The requirement is that the wind direction indicator be appropriate for the site conditions and visible during an emergency
• State-plan OSHA states (such as California's Cal/OSHA) may impose additional requirements
• EPA's Risk Management Program (40 CFR Part 68) complements OSHA 1910.119 and may also reference wind direction monitoring as part of offsite consequence analysis

Practical impact: For US industrial buyers specifying windsocks under OSHA 1910.119, the key question is whether the windsock specification is appropriate for the hazards on site. Aviation-grade windsocks (meeting FAA AC 150/5345-27F fabric requirements) are commonly used at general industrial and process safety facilities. Higher-hazard sites may require heavier-duty specifications, similar to the COMAH distinction in the UK.

Standards Comparison Table

Aspect	CAA CAP 168 (UK)	FAA AC 150/5345-27F (US)	ICAO Annex 14 (International)	EASA EU 139/2014 (EU)	COMAH / HSE (UK Industrial)	OSHA 1910.119 (US Industrial)
Territory	United Kingdom	United States	193 ICAO member states	EU member states	United Kingdom	United States
Sector	Aviation	Aviation	Aviation	Aviation	Industrial / process safety	Industrial / process safety
Windsock length	Per ICAO (3.6 m / 12 ft minimum)	Size 1: 8 ft (2.5 m), Size 2: 12 ft (3.75 m)	Not less than 3.6 m (12 ft)	Per ICAO (3.6 m minimum)	Not specified by code (site-appropriate)	Not specified by code (site-appropriate)
Throat diameter	Per ICAO (0.9 m / 36 in minimum)	Size 1: 18 in (0.45 m), Size 2: 36 in (0.9 m)	Not less than 0.9 m (36 in)	Per ICAO (0.9 m minimum)	Not specified by code	Not specified by code
Full extension wind speed	15 knots	15 knots	15 knots	15 knots (per ICAO)	N/A	N/A
Direction accuracy	Plus or minus 5 degrees at 3 knots	Plus or minus 5 degrees at 3 knots	Indicate direction at 3 knots	Per ICAO	N/A	N/A
Colour	Contrast with background, fluorescent orange standard	White, yellow, or orange (purchaser specified)	Single colour or two-colour banding recommended	Per ICAO	High visibility (site-appropriate)	High visibility (site-appropriate)
Illumination	Required for night operations	Style I-A: 2 fc min. Style I-B: 10-30 fL avg	Required for night operations	Per ICAO	Site-dependent	Site-dependent
Fabric specification	Not prescribed in detail (defers to ICAO)	Min. breaking strength 150 lb warp and fill. Water repellent.	Truncated cone, fabric	Per ICAO	Higher-hazard sites expect 400 GSM, chemical-resistant	Site-appropriate
Falcon Premium compliant	Yes	Yes	Yes	Yes (via ICAO)	Lower-tier sites only	General industrial, yes. High-hazard, specify HD

What Your Auditor Is Looking For

Compliance is not just about the product on the pole. It is about the documentation in the safety file. Here is what auditors across aviation and industrial sectors expect.

Documentation

Your auditor wants to see a paper trail that connects the windsock on site to the standard it is required to meet.

The essentials:

• Certificate of Conformity stating which standards the product was manufactured to (CAA CAP 168, ICAO Annex 14, FAA AC 150/5345-27, or site-specific requirement). Every Falcon order ships with a Certificate of Conformity
• Product specification sheet detailing fabric weight, material type, colour standard, hardware specification, and dimensions. This must match the product actually installed
• Purchase order or invoice as evidence of procurement from a traceable supplier
• Installation date recorded in the maintenance log or safety file

Specification match

The auditor will check that the installed windsock matches the specification in the site safety documentation or aerodrome manual. This means:

• The fabric weight and material type match the specification (200 GSM PU coated polyester for aviation, 400 GSM chlorosulfonated polyethylene for upper-tier COMAH)
• The colour standard matches (EN471 fluorescent orange is the default for UK and international aviation)
• The size is appropriate for the application and location
• The attachment type is compatible with the installed mounting hardware

A common audit finding is a windsock that has been replaced with a non-specified product. If the original specification called for a 200 GSM PU coated polyester windsock to EN471, and someone replaced it with a cheaper, lighter alternative, the auditor will flag it.

Replacement evidence

Windsocks are consumable items. They degrade through UV exposure, wind stress, and weather. Most professional installations require replacement every 6 to 18 months depending on conditions.

What auditors want to see:

• A scheduled replacement programme (not just replacement when visibly degraded)
• Dated records of each replacement, including the product installed and the supplier
• Evidence that the replacement product matches the original specification
• For aviation sites: confirmation that the replacement was noted in the aerodrome maintenance log
• For COMAH sites: confirmation that the wind direction indicator was maintained as part of the emergency preparedness schedule

Common audit failures

• No Certificate of Conformity on file
• Specification on file does not match the installed product
• No replacement records or replacement dates
• Windsock visibly degraded (torn, faded, not extending correctly) at time of inspection
• Illumination not functional during night operations
• Windsock obstructed by adjacent structures or vegetation growth

How to Verify Compliance Before You Buy

The time to verify compliance is before the purchase order, not after the audit. Here is how to confirm that a windsock meets your requirement.

1. Identify your applicable standard

Determine which regulatory framework applies to your site:

• UK aerodrome: CAA CAP 168
• US airport (Part 139): FAA AC 150/5345-27F
• International aviation: ICAO Annex 14
• EU aerodrome: EASA EU 139/2014 (referencing ICAO Annex 14)
• UK industrial / COMAH site: HSE guidance, with specification appropriate to your tier
• US process safety facility: OSHA 29 CFR 1910.119

2. Check the supplier's published specification

A credible supplier publishes the full product specification on the product page. You should be able to verify:

• Fabric type and weight (e.g. 200 GSM PU coated polyester)
• Colour standard (e.g. EN471:2003 fluorescent orange)
• Hardware specification (mouth ring material, harness type, fixing type)
• Compliance standards the product is manufactured to
• Available sizes with dimensions

If the supplier does not publish this information, ask yourself why.

3. Request the Certificate of Conformity before ordering

Any supplier who manufactures to a recognised standard should provide a Certificate of Conformity. This document states which standards the product has been manufactured to and is signed by the manufacturer.

At Falcon, we issue a Certificate of Conformity with every order. It references CAA CAP 168, ICAO Annex 14, and FAA compliance. You do not need to request it separately.

4. Confirm the specification matches your requirement

Cross-reference the supplier's published specification against your site's documented requirement. If your aerodrome manual specifies a 12-foot windsock to CAA CAP 168 in fluorescent orange, confirm that the product you are ordering meets those exact parameters.

5. Keep the documentation

File the Certificate of Conformity, the product specification sheet, and the purchase order in your safety documentation. When the auditor asks, the answer is already on file.

Know it meets the standard before you buy it, not after.

Frequently Asked Questions

What standard does an airport windsock need to meet?

It depends on the territory. In the UK, airport windsocks must meet the requirements of CAA CAP 168. In the United States, FAA AC 150/5345-27F applies. Internationally, ICAO Annex 14 provides the baseline standard that most national aviation authorities adopt. All three require the windsock to extend fully at 15 knots and indicate wind direction within plus or minus 5 degrees at 3 knots.

What is the difference between ICAO and FAA windsock requirements?

ICAO Annex 14 sets the international baseline. The FAA AC 150/5345-27F builds on ICAO with additional detail on fabric strength testing, supporting structure specifications, lighting requirements, and equipment qualification testing. The FAA standard is more prescriptive. It specifies minimum breaking strength (150 lb warp and fill), temperature tolerance (minus 67 degrees F to 131 degrees F), and detailed photometric requirements for lighted assemblies.

What colour should a windsock be?

Aviation standards require the windsock to contrast with its background. Fluorescent orange to EN471 is the most widely accepted colour for aviation and industrial applications. The FAA permits white, yellow, or orange, with the colour specified by the purchaser. ICAO recommends a single colour (white or orange) or alternating bands of two contrasting colours (typically orange and white, or red and white).

How often should a windsock be replaced?

Most professional windsocks require replacement every 6 to 18 months, depending on UV exposure, wind conditions, and local weather. Aviation and industrial auditors expect to see a scheduled replacement programme with dated records. A visibly degraded windsock (faded colour, torn fabric, failure to extend properly) is a common audit finding.

Are windsocks required at heliports?

Yes. ICAO Annex 14 Volume II (Heliports) requires at least one wind direction indicator at heliports. CAA CAP 168 and FAA regulations extend this requirement to licensed and certificated heliports respectively. Offshore helidecks (governed by HSE and CAA CAP 437 in the UK) also require wind direction indicators, typically to a heavier-duty specification suitable for the marine environment.

What is the COMAH requirement for wind direction indicators?

COMAH does not define a specific windsock standard by code number. The requirement is part of the site safety report: wind direction indicators must be appropriate for the site hazards, permanently installed, and maintained for reliability during emergencies. In practice, upper-tier COMAH sites handling toxic or flammable substances are expected to install heavy-duty windsocks (400 GSM, stainless steel hardware, chemical-resistant construction). Lower-tier sites may use aviation-grade products.

Do windsocks need to be certified?

Aviation windsocks should be supplied with a Certificate of Conformity from the manufacturer, stating which standards the product meets. For US federally funded airport projects, equipment must be qualified under the FAA Airport Lighting Equipment Certification Program. For industrial applications, the certificate provides audit evidence that the installed product meets the site safety report specification.