September 26, 2015 (AirportChandigarh.com): Chandigarh airport is one of the major airports of North India with total annual passengers of more than 12 lacs (one hundred and twenty thousand). The international terminal was inaugurated on 11th September 2015. However, the airport still has CAT-I Instrument Landing System (ILS).
An ILS provides precision guidance to an aircraft approaching and landing on a runway, to enable a safe landing. CAT- I is the basic ILS. Cat II/III ILS's are more highly calibrated.
During foggy weather when the visibility is low, flights usually get cancelled because CAT-I lacks the necessary technology which CAT-II/III provides. CAT-I requires a minimum decision height (i.e., the height at which a decision must be made by the pilot to either continue the approach and land or to abort the landing) of 200 feet and minimum visibility of 1.2 km. These requirements may not always be fulfilled, especially during foggy weather.
CAT-II works at a minimum decision height of 100 feet and a minimum visibility of 200 meters. CAT-III has no minimum decision height, although, depending on the country of operation, there is a visibility restriction. CAT II/III systems need to be provided with greater protection. That is why the holding points (i.e., a traffic pattern, usually circular, flown by aircraft awaiting clearance to land at an airport) are set further back from the runway than those associated with CAT-I operations. ILS affects the landing of the flight during low visibility which has nothing to do with the landing of fights at night time.
As the airport is going international the traffic airflow would be high than the current levels. This calls for the need of more informed landing systems. CAT-II/III clearly wins in every round than the CAT-I due to its enhanced decision height support and improved visibility. Thus, even if CAT-II is implemented, it is pragmatic to believe that this upgrade would drastically reduce the number of flights being cancelled due to weather disturbances.