The Instrument Landing System (ILS) on two runways at the Chennai airport is not functioning since Monday night, and it may take three months to rectify the problem, airport sources said.

The Airports Authority of India (AAI) has issued a ‘Notice To Airmen’ in this regard. This would mean that pilots would have to follow a “non-precision” approach while landing.

A senior pilot said if visibility levels were normal, landing would not be a problem. However, if conditions are poor, arrival of aircraft would be delayed. Flights could also be diverted to nearby airports in some cases. As far as Chennai was concerned, the only problem would be delay in the arrival of aircraft, as landings would have to be sequenced, he said.

Available records showed that the ILS is a ground-based instrument approach system, which provides precision guidance to an aircraft approaching and landing on a runway. It consists of two independent sub-systems – providing lateral guidance to an aircraft approaching a runway and the aircraft guidance is provided by the ILS receivers in the aircraft.

Airport sources said the AAI had issued NOTAM for a period of three months as there seems to be a major fault in both the ILS systems on the runways. When contacted, D. Devaraj, Regional Executive Director, AAI, Southern Region, said there was some problem in the system when whitewashing work was taken up at the Air Traffic Control tower building. “The ILS facility is available, only some small fine-tuning is required,” he said.

Another senior AAI officer said there was some technical problem. Following this, the AAI informed the pilots that the height from which they have to sight the runway before landing had been increased from the existing level. Because of the change in the height restriction, the movement of flights will not be delayed, he said.

  • AAI has issued a ‘Notice To Airmen’

  • Pilots will have to follow a “non-precision” approach while landing