Meteorological Services

The objective of an aviation meteorological service is to contribute towards the safety, regularity and efficiency of international air navigation by the provision of timely and accurate weather information.  It will be apparent that aircrew must be able to access accurate weather information when planning their flight and given the changing nature of the earth’s weather patterns this information will need to be updated as necessary to ensure that a planned flight can be completed safely.  This is achieved by providing necessary meteorological information to aircraft operators, flight crew, air traffic services units and airport management through network of international communication systems which ensures close liaison between those supplying meteorological information and those using it.

ICAO Responsibilities

As a signatory to the Convention on International Civil Aviation, the UK and its Overseas Territories are obligated to provide meteorological information to international air transport with the nature and extent of the service required being identified in ICAO Annex 3. In the Cayman Islands, an ICAO compliant service is provided by the Cayman Islands National Weather Service (CINWS).

The National Weather Service provides this service by collecting, analyzing and disseminating meteorological information received from its own sensors to both local and international users of the service. This information includes local actual weather conditions, forecast conditions, weather warnings and upper-air actual information derived from the radio.

Regulatory Requirements

Article 7(1) of The Air Navigation (Overseas Territories) Order 2013, (AN(OT)O) or (the Order) as amended, gives effect to the Convention on International Civil Aviation requiring the Governor to ensure that the Annexes to the Convention are complied with. Thereafter, Article 7(2)(a) requires the Governor to provide or secure a meteorological service to meet the needs of international air navigation.

Consequently, Article 7 of the Order identifies the requirement for the provision of a meteorological service for aviation and for its regulation under Annex 3 of the Convention. In addition, ASSI have published OTAR 174 which provides additional regulation particularly in respect of oversight relationships. Further guidance is provided by OTAC 174-1 and OTAC 174-2 in relation to Definition of Service and Qualification of Personnel respectively.

In addition, OTAR 139.33 (b)(6)(iii) specifies that for an aerodrome to be certified, appropriate arrangements must be in place for the provisions of the meteorological services.

OTAR Part Certification of Aerodromes, Subpart 139.B.31 (e) (6) (i) specifies that for an aerodrome to be certified, appropriate arrangements must be in place for the provisions of the Meteorological Service.

There are no OTARs for Annex 3 (Met) so regulatory audits of the service provider will ascertain conformance with the provisions of Annex 3 itself in relation to the services set out by the Governor.

Meteorological Service Products

The Meteorological Service generates a variety of products to assist aeronautical users to carry out their functions.

The CINWS produces a number of meteorological information products and the key ones are identified below:

  1. Aerodrome Weather Observations known as METARS are produced every hour, on the hour and include surface wind, visibility, present weather, cloud, air and dew-point temperature and atmospheric pressure. These reports are complemented by special reports whenever any parameter changes beyond pre-fixed limits of operational significance.
  2. Aerodrome Forecasts known as TAFS are issued every six hours and are valid for between 12-30 hours. TAFs include surface wind, visibility, weather, cloud and temperature, Aerodrome forecasts are kept under continuous review and are amended by the meteorological office as necessary. Where TAF cannot be kept under continuous review it will be cancelled.
  3. Pilot Briefings. To assist pilots with their flight planning, meteorological briefings can be provided on request. Such briefings comprise details of en-route weather, upper winds and upper-air temperatures (usually provided in the form of meteorological charts) reports and forecasts for the destination aerodrome and its alternates. Where necessary, warnings related to hazardous phenomena en-route are provided as follows:
    • Aerodrome Warning: Issued when a weather phenomenon that may adversely affect aircraft on the ground, including parked aircraft, aerodrome facilities and services is observed or predicted.
    • Wind shear Warning: Issued when the observed or expected existence of wind shear could adversely affect aircraft on the approach path or take-off path or during circling approach between runway level and 500 m (1600 ft) above that level and aircraft on the runway during the landing roll or take-off run.
    • SIGMET info: Issued when specified en-route weather phenomena that may affect the safety of aircraft operation in the flight information region (FIR) is observed or predicted.
    • AIRMET info: Issued when specified en-route weather phenomena that may affect the safety of low-level flights below 10,000ft is observed or predicted

Aerodrome forecasts include surface wind, visibility, weather, cloud and temperature, and are issued every three or six hours for a validity period of 9 to 24 hours. Aerodrome forecasts are kept under continuous review and are amended by the meteorological office, as necessary.

To assist pilots with their flight planning, meteorological briefings are carried out. Briefings comprise details of en-route weather, upper winds and upper-air temperatures, often given in the form of meteorological charts, warnings related to hazardous phenomena en-route, and reports and forecasts for the destination aerodrome and its alternates.

Civil Aviation Authority

The Civil Aviation Authority of the Cayman Islands provides the Meteorological Service with safety oversight to ensure regulatory compliance with current legislation and regulation including Annex 3 and the associated OTARs.

Compliance is assessed during routine inspections and a formal in-depth audit which is carried out every two years against a regulatory checklist. The audit samples various aspects of the Meteorological Service including but not limited to, meteorological equipment, calibration records, manning levels, personnel qualifications, processes & procedures, meteorological observations, forecasts and warnings issued.