ICAO requires States to conduct inspections of its aeronautical meteorological stations at sufficiently frequent intervals to ensure that a high standard of observation is maintained, that instruments and all their indicators are functioning correctly, and that the exposure of the instruments has not changed significantly.

There is also a need to ensure that the aeronautical met observations provided for civil aviation are accurate, timely and coded correctly, in line with international standards.

Met observing covers the following aspects:

• Observing, reporting and encoding the weather elements required for METAR reports and local reports to ATS;
• Sensors and equipment used to observe and report weather conditions, as well as systems to encode, disseminate and display the information.
• The provision of accurate reports within agreed timescales;
• Understanding the process and criteria for issuing 'special' weather;
• Demonstrating the ability to make observations at night;
• Demonstrating a basic understanding of the meteorological hazards for aviation.

ICAO Annex 3 provides standards and recommended practices relating to met observing and these are included within the requirements laid down in CAP 746, Meteorological Observations at Aerodromes, which is edited by the Met Authority. CAP 746 further requires ongoing competence of the Met observer, to ensure that the most up to date observing techniques and latest coding are used.