Low visibility: Main runway shut for only 6 hours, flights late by 20 mins

MUMBAI: On Friday, the main runway at the city airport was shut for about six hours as work on constructing two rapid exit taxiways commenced in full swing.
The closure, which will occur every day from 9am to 5pm till June 2014, was delayed by an hour as visibility levels in the morning dropped again, making it impossible to operate flights on the secondary runway.
Officials said that flights were delayed by 15-20 minutes in the morning, but those operating in the afternoon were on time due to less traffic. They added that the visibility level fell below the required minimum for the instrument landing system (ILS) of 1,200m on the secondary runway. "This is why the closure was delayed by an hour," said an official.
The main runway was again opened for an hour when a delegation of Vietnamese VIPs was to land at the airport, said an official.
Airport officials said that flight delays might increase after winter sets in as visibility levels are likely to drop further in December and the air traffic control (ATC) would not be able to use the secondary runway if the drop is drastic. "Unlike the main runway, which requires a minimum visibility of 800m, the secondary runway needs at least 1,200m even when the ILS is in use. Hence, in case of a major drop in visibility levels, the runways will have to be changed. This would result in at least 30 minutes holding time for flights while the change takes place, and then some more time before they can land to take-off in a queue," said an official.
In addition, the secondary runway, unlike the main runway that handles about 45 flights/hour, can accommodate only 38 flights/hour. "There is bound to be a delay of 20-30 minutes daily even on a good day as departures are scheduled back-to-back between 9am and 12pm," an airport official said.
But these seven months of delays are expect to result in smoother flight operations after June. The two rapid exit taxiways will reduce the runway occupancy time of aircraft enabling the ATC to handle more flights. "This would also decongest the airport and reduce delays. We would be able to handle 48-50 flights/hour," said an ATC official.