Last week, a test flight landed at Srinagar airport after sunset, demonstrating that the airport is safe for night landing. Once all the regulatory procedures are completed, passengers will be able to take night flights to the summer capital of Jammu & Kashmir. When, and how, is an airport suitable for night landing? In Srinagar’s case, two main factors came together to make it possible – and upgrade of the runway lighting system at the airport, and an extension of watch hours by the Indian Air Force, to which the airport belongs.
India has 101 airports; until last year, about 35 did not have night landing facilities. These were primarily smaller airports that saw lower passenger traffic. According to a Civil Aviation Ministry source, it is usually the Airports Authority of India, which manages most of the airports in India, that takes up a particular one for consideration for providing night landing facilities, once airlines have shown an interest in post-sunset operations.
The main requirement for night landing is that the runway approach lighting system include a series of light bars with strobe lights installed at the end of the runway. Such a system serves a runway that is equipped with an instrument landing system, or ILS. With modernisation of aircraft and airport equipment, ILS is replacing the traditional approach, under which pilots landing aircraft depended on what was visible to them.
ILS uses a series of navigational aids to help pilots land the aircraft if they cannot establish visual contact with the runway. As per the International Telecommunication Union, ILS is a system which provides the aircraft “with horizontal and vertical guidance just before and during landing and, at certain fixed points, indicates the distance to the reference point of landing”.
It is also important for airport operators to have lighting along the runway edge, so that pilots landing at night are able to make visual contact and align the aircraft with the centre of the runway.
Instrument approach operations in India are classified on the basis of the “lowest operating minimum range”, below which approach to the runway requires a visual reference. At the low end is the CAT-I category, under which the “touchdown zone” cannot be lower than 550 metres; in other words, the landing aircraft can make contact with the tarmac only when the pilot can see at least 550 m ahead. Under CAT-II, this can go down to 300 metres. Under CAT-IIIA and CAT-IIIB, the touchdown zone can be as low as 175 metres and 75 metres, respectively. Currently at Indian airports, CAT-IIIB is the most modernised version of ILS installed. Usually, the system is installed at airports that are expected to experience low-visibility conditions during the winter, due to fog. At present, CAT-IIIB systems are installed at Delhi, Lucknow, Jaipur, Amritsar and Kolkata airports.
Simply installing the system at airports, however, is not enough. Airlines also have to use aircraft that are compliant with the latest systems and engage pilots who are trained to make instrument-based landing. Most major airlines flying frequently out of airports that experience low-visibility conditions, in fact, do have the relevant aircraft. Generally, however, they tend to train only those pilots who will be flying to these airports regularly.