CAP 437: Standards for offshore helicopter landing areas

Overview

CAP 437, published by the UK Civil Aviation Authority (CAA), defines the standards for the design, operation and safety of offshore helicopter landing areas.

It covers helideck layout, lighting, obstacle clearance, meteorological instrumentation and, where applicable, Helideck Monitoring Systems (HMS). These standards apply to all UK-registered helicopters and offshore installations, including oil and gas platforms, floating production units and offshore wind substations.

On the UK Continental Shelf (UKCS), compliance with CAP 437 is recognised by the Health & Safety Executive (HSE) as evidence of conformity with offshore safety legislation.

Scope and application

CAP 437 applies to both fixed and mobile offshore installations. Fixed helidecks, such as those on production platforms or substations, are evaluated primarily against design, lighting and meteorological requirements.

For moving helidecks, such as those on semi-submersible rigs, FPSOs and support vessels, CAP 437 also addresses motion and environmental monitoring. In these cases, the Helideck Certification Agency (HCA) provides detailed implementation guidance in its document Standard Measuring Equipment for Helideck Monitoring Systems and Weather Data, currently Revision 9c.

Fixed vs moving helidecks

Both categories fall under CAP 437. The difference lies in their operational environment.

Relationship with ICAO standards

CAP 437 builds on ICAO Annex 14, Volume II (Heliports), expanding its principles for offshore conditions. It adds guidance on helideck geometry, lighting, obstacle protection and environmental monitoring.

International recognition

Although developed in the UK, CAP 437 has become the international benchmark for offshore helicopter landing areas. Classification societies, including ABS, DNV, Lloyd’s Register and Bureau Veritas, typically specify CAP 437 as the minimum standard for helidecks on vessels and floating units when no local aviation regulation applies.

Some countries have their own frameworks derived from CAP 437 principles, aligned with its intent and structure:

This broad adoption has established CAP 437 as the de facto global best practice for helideck safety, meteorological accuracy and monitoring performance.

Meteorological and monitoring requirements

A key element of CAP 437 is reliable meteorological data to support flight operations. Each helideck should supply accurate, locally measured information on:

For moving helidecks, this data is integrated within the HMS, which combines the meteorological readings with deck-motion parameters:

This gives pilots and offshore crews a consistent, real-time picture of landing conditions.

Current edition and HCA implementation

The latest issue, CAP 437 Edition 9 Amendment 1 (January 2026), introduces a range of minor updates and a major operational enhancement through a new appendix: the Master Minimum Helideck Equipment List (MMHEL).

“Rev 9b” and “Rev 9c” refer to the HCA’s implementation standards, not revisions of CAP 437 itself. They explain how CAP 437 Edition 9 is applied to moving helidecks in practice. See HCA Rev 9c (current) and Rev 9b.