Gardermoen has had considerable problems with fog and freezing rain, and has several times had a complete close-down. This was also a problem at Fornebu, and reported to be at Hurum as well. On average, there is super cooled rain three times per month during the winter. The use of deicing fluids is restricted since the area underneath the airport contains the Tandrum Delta, one of the country's largest uncontained quaternary aquifers (underground water systems). On 14 December 1998, a combination of freezing fog and supercooled rain caused glaze at Gardermoen. At least twenty aircraft engines were damaged by ice during take-off, and five aircraft needed to make precautionary landings with only one working engine. On 18 January 2006, an Infratek deicing system was set up, that uses infrared heat in large hangar tents. It was hoped that it could reduce chemical deicers by 90%, but the technique has proved unsuccessful.
