A. Ranganathan

Every year, the air traffic disruptions out of Delhi due to fog make the headlines. And every year, we hear the same statements by the civil aviation authorities. But nothing happens. Airlines are warned either by the Civil Aviation Minister or by the Director-General of Civil Aviation to get their act together or face the stick. Are airlines responsible for this mess or is it the faulty system that is in place? For every step that aviation moves forward, the outdated rules and policies takes the sector three steps back.

When Mumbai airport was shut down for three days in 2005 due to flooding, the authorities blamed unprecedented rains. All the ground equipment were damaged due to water logging and it takes time to replace them. Delhi faces the fog problem every winter and the usual noises are made about the airport being ready for CAT II and CAT III Instrument Landing Systems but not the pilots. Has anyone gone into the bureaucratic hurdles that the airlines face?

Ancient Rules

The rules and procedures are so ancient that modern solutions cannot be found unless there is a total change in mindset. The authorities must take off the blinkers and look beyond the four walls of the civil aviation system in India.

Air passengers don't travel only from and to Delhi or Mumbai. They travel to every part of India. Do we have to worry only about passengers travelling only to these two metros? The authorities may hide behind the fact that London's Heathrow airport faced similar chaos last week. But the news did not highlight the fact that the airport did not shut down. Airlines capable of CAT III could continue to operate; with this, operations are possible even in zero visibility conditions. Airline operations in India grind to a halt only because of the over-dependence on "ground based" aids and systems. All the navigation procedures are still based on the old VOR (very high frequency omni directional range finder) system which has an acceptable error of 4 degrees. This means an error of 4 miles in 60 miles. The Indian authorities continue to depend on this even as the rest of the world is changing to what is called the RNP/RNAV approaches.

GPS-fed airborne systems

RNP stands for Required Navigation Performance and these are airborne systems (which every aircraft has) and which gettheir bearings from global positioning satellite systems (GPS) and the flight management computer systems that all modern aircraft use. On modern aircraft the system has an error of just around 20 feet. Since all runways are 150-feet wide, an error of 20 feet would keep the aircraft well within the runway. The system is extremely accurate and many airlines worldwide have started adopting this procedure.

The Lhasa airport case

The best example of the RNP/RNAV system is the approach procedure for Lhasa airport in Tibet. This airport is surrounded by mountains rising to 20,000 feet-plus. Flights into Lhasa were possible only when the visibility was more than 10 km and the cloud base was more than 21,000 feet. Chinese airlines operating to Lhasa faced diversions to neighbouring airports almost 70 per cent of the time. Because of this it was difficult to design an instrument approach and the airport operation was confined to clear weather conditions, as it is in Leh.

But the forward-looking civil aviation authority in China went in for the bold initiative of RNP/RNAV approach. Today, flights operate to Lhasa with reduced visibility and ceiling requirements and the diversion rate is down to less than 10 per cent. The RNP approach system works on the principle of "threading a needle". The approach path is designed to proceed through a series of small windows whose outer limits conform to the limits of the RNP rules. These windows are placed so close to one another that the aircraft literally threads through the approach path. All modern aircraft have accurate flight management systems and autopilots. With proper training and correct use of the RNP procedures, the approach can be made even in poor visibility.

The RNP/RNAV approaches have the advantage of 24/7 non-stop availability. They are not affected by weather and the position over the ground is very accurate. Most important, they do not require any ground-based equipment. Knowing the pace at which the bureaucracy works in India, sanctions for any ground-based equipment would probably come long after technology has made the equipment obsolete.

Environment friendly

The RNP procedures are also environmentally friendly. They use less airspace and, thus, an aircraft has to travel less distance. This means fuel saving for all airlines and the resultant reduction in engine usage means less environmental pollution.

The use of RNP procedures have several benefits. To quote from document of the Federal Aviation Authority of the US: "By refining navigation system performance and airspace containment to a 99.999 per cent certainty, maximum benefit can be derived from RNP. The accurate, repeatable path, integrity and continuity ensure procedures will be flown in the same manner by all aircraft. Controllers can then expect aircraft to be at a specific position with a high degree of confidence, thus maximising safety and the efficient flow of aircraft through airspace. This improved containment will be used to refine obstacle evaluation when developing routes and procedures."

The other benefits are:

Reduced route separation resulting in increased airspace capacity and efficiency,

Improved obstacle clearance limits,

Lower landing weather minimums,

Reduced pilot and controller workload, and

More "fly direct to" capability and capacity.

There is no use threatening airlines but it is more important to upgrade to the system that is already in use worldwide. Recently, the Prime Minister made a statement that the economic progress in India is slowed by the Chalta Hai attitude. The same applies to civil aviation. Winter passes quickly and we have another nine months to procrastinate before starting the blame game.

(The author is an airline pilot with 19,000 hours experience and specialises in accident-prevention studies.)

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