General CAP 437 overview

CAP 437 presents the criteria required by the CAA in assessing the standards of offshore helicopter landing areas for worldwide use by helicopters registered in the UK.

These landing areas may be located on:

  • fixed offshore installations;
  • mobile offshore installations;
  • vessels supporting offshore mineral exploitation;
  • offshore wind farms; or
  • other vessels, e.g. tankers, cargo vessels, passenger vessels.

The criteria in this publication relating to fixed and mobile installations in the area of the UK Continental Shelf (UKCS), whether they are operating for oil and gas or renewable energy sectors, provide standards which are accepted by the HSE and referred to in HSE offshore legislation.

The criteria address minimum standards required in order to achieve a clearance which will attract no helicopter performance (payload) limitations. CAP 437 is an amplification of internationally agreed standards contained in ICAO Annex 14 to the Convention on International Civil Aviation, Volume II, ‘Heliports’.

Additionally, it provides advice on ‘best practice’ obtained from many aviation sources. ‘Best practices’, naturally, should be moving forward continuously, and it should be borne in mind that CAP 437 reflects ‘current’ best practice at the time of publication.

There may be alternative equivalent means of meeting the criteria presented in CAP 437, which will be considered on their merits.

Additional criteria are given relating to vessels used in support of offshore mineral exploitation or renewable energy, which are not necessarily subject to HSE offshore regulation and also for other vessels such as tanker, cargo and passenger vessels.

In this publication, the term ‘helideck’ refers to all helicopter landing areas on fixed or floating offshore facilities used for the exploration or exploitation of oil and gas or exploitation of renewable energies. For helicopter landing areas on vessels, the ICAO term ‘shipboard heliport’ may be used in preference to ‘helideck’.

As standards for best practice, this document applies the term “should” when referring to either an ICAO Standard or a Recommended Practice. The term “may” is used when a variation or alternative approach could be acceptable to the CAA.

The UK HSE accepts that conformance with CAP 437 will demonstrate compliance with applicable offshore regulations. CAP 437 is under continuous review resulting from technological developments and experience; comments are always welcome on its application in practice. The CAA should be contacted on matters relating to interpretation and applicability of these standards and Aviation Law.

Meteorological observations

In addition to the data covered by paragraph 6.3, it is strongly recommended that installations are provided with an automated means of ascertaining the following meteorological information at all times:

  • wind speed and direction (including variations in direction);
  • air temperature and dew point temperature;
  • QNH and, where applicable, QFE;
  • cloud amount and height of base (Above Mean Sea Level (AMSL));
  • visibility; and
  • present weather.

Reporting of meteorological information

Up-to-date, accurate meteorological information is used by helicopter operators for flight planning purposes and by crews to facilitate the safe operation of helicopters in the take-off and landing phases of flight.

Reports should be provided by the Met Observer at the installation concerned and not by Met Observers located on neighbouring installations or from standby boats in the vicinity.

Collection and retention of meteorological information

Records of all meteorological reports that are issued are required to be retained for a period of at least 30 days.

Pre-flight weather reports

The latest weather report from each installation should be made available to the helicopter operator one hour before take-off. These reports should contain:

  • the name and location of the installation (latitude and longitude in degrees and decimal minutes);
  • the date and time the observation was made;
  • wind speed and direction;
  • visibility;
  • present weather (including presence of lightning);
  • cloud amount and height of base;
  • temperature and dew point;
  • QNH and QFE; and
  • details of unserviceable Met sensors (including the original date that the sensor became unserviceable).
    Additional information should be provided from mobile installations and vessels as follows:
  • Significant Heave Rate;
  • Max. Heave and Max. Average Heave Rate
  • Max. pitch and Max. roll; and
  • Max. helideck inclination.

Real-time web-based systems

North Sea offshore installations should supply meteorological information to the UK oil and gas industry’s web-based system (Helimet).

Helimet provides an efficient and consistent method of submitting weather reports and information from automated sensors to the helicopter operators.

This enables a greater sharing of weather information so that helicopter operators, installation duty holders and others can access the latest information in one place and in real time, thereby enhancing users’ situational awareness of weather conditions across the North Sea.

Helimet also performs some verification of information submitted via the system which reduces the risk of data entry errors.

Where appropriate, AUTO METARS may be generated from these reports which, provided all the required parameters are being generated, may be made available on the Aeronautical Fixed Service (AFS) channels, including the Aeronautical Fixed Telecommunications Network (AFTN).

Meteorological observer training

Personnel who carry out meteorological observations on offshore installations should undergo formal meteorological observer training and be certificated by a CAA approved training organisation for this role.

Observers should complete refresher training provided by a CAA approved training organisation every two years to ensure they remain familiar with any changes to meteorological observing practices and procedures.

Training on the use of contingency meteorological equipment and procedures should be provided to enable a suitable level of accuracy and regularity of observations to be maintained in case of the failure or unavailability of automated sensors.

Calibration of meteorological equipment sensors

Calibration of primary and back-up meteorological equipment sensors used to provide the data listed in paragraph 6.12 should be periodically carried out in accordance with the manufacturers’ recommendations in order to demonstrate continuing adequacy for purpose.

The latest version of this document is available in electronic format at

More Information about CAP 437

Then check out these information pages:

Standard Measuring Equipment for Helideck Monitoring System and Weather Data Rev 8c

Standard Measuring Equipment for Helideck Monitoring System and Weather Data Rev 9b

Or feel free to contact us to discuss your new Helideck Monitoring System, needs or if you are looking at upgrades or recommended service routine for your existing systems.

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