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Fog at Auckland Airport and Category IIIB

In a typical year Auckland Airport could expect fog at the airport for some part of the day for 12 to 16 days. While fog in the area would probably result in delays to aircraft either arriving or departing, typically diversions would only be expected on three to 11 of those days.

Auckland Airport works with Airways New Zealand (air traffic control) and the airlines to continually monitor where the fog is located and the visibility on the airfield – known as the runway visual range, or RVR. Airways will inform the pilot of the current RVR on the ground and the pilots will make the decision whether to begin an approach to the airfield or not.

Often, the fog will move in and out of the airfield and flights can take advantage of these breaks to land or take off.

In conjunction with Airways New Zealand and airlines, Auckland Airport is jointly working to install additional equipment that will permit aircraft to land during fog. This involves implementing the Instrument Landing System (ILS) to a ‘Category III B’ level. The work also includes installation of new lighting, written procedures and certification. The system will be introduced in stages and it is anticipated that it will be fully operational in May 2008.

The first stage is reached when the system is installed to a Category II level that allows for landing when there is horizontal visibility not less than 350 metres and the pilot can see the ground from a height not lower than 100 feet.

The second and final stage of system installation allows for Category III B operation. This means that if the horizontal visibility on the runway is greater than 50 metres, and the aircraft and pilot have the appropriate ratings, the aircraft can land. Without Category III, 800 metres horizontal visibility is required, and more than 200 feet of visible height.

When implemented, Auckland will be one of the first airports in Australasia to have such a system.

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