Other Aspects of the Diego Garcia story

By Paramanund Soobarah

Four of the US’s most important tracking stations are located at Cape Canaveral, Florida, at Ascension in the Atlantic, at Kwajalein in the Marshal Islands in the Pacific, and — you guessed it – at Diego Garcia, our own beloved atoll, for the Indian Ocean

Washington’s ‘unsinkable aircraft carrier’: Diego Garcia Military Base


The sixties were a decade of great tension in the world – and in Mauritius. The Cold War was on. The French were losing the fight against the Communists in Indo-China, and the US stepped in to bolster them. President Kennedy sent some help and, sadly, in 1962, also authorized the US Air Force to spray Agent Orange and other herbicides over rural areas of South Vietnam to kill off vegetation to deprive communist guerrillas of sustenance and cover. In August 1964 President Johnson formally took America into the war in Vietnam, under the pretext of an alleged attack by Communists on a US battleship, and the search for a base in the neighbourhood began. Somebody in the US military spotted the conveniently situated, minuscule island of Diego Garcia still under British administration. An approach was made to the British government, then in the process of withdrawing from their Empire under an East of Aden policy (which became an East of Suez policy, and later again an East of Gibraltar policy; sixty years later, they are still grappling with an East of Dover policy).

In addition to these global tensions, there was another bitter rivalry going on in the tiny corner of the world named Mauritius, a British colony. The autonomy and independence seekers led by Sir Seewoosagur Ramgoolam were engaged in a bitter struggle with the opponents of Independence. The British had made up their mind to withdraw from the Island under their general decolonization policy. When approached by the Americans in 1964 about Diego Garcia, the civil servants in the British administration dealing with the matter, thoroughly familiar with the struggle in Mauritius for and against Independence, saw an opportunity to wade into the situation to secure some advantage. A promise of Independence against hiving off Chagos, the archipelago around Diego Garcia would suit their purpose; thus was Prime Minister Harold Wilson advised.

UK-US Deal

Faced with the opposition to Independence in his own country, there are no prizes for guessing the reaction of Sir Seewoosagur. The archipelago was hived off and, in 1966, the British and American governments signed an agreement “without Parliamentary or Congressional oversight” giving the US the right to build and maintain a base on Diego Garcia “until its need for military facilities had disappeared”, in other words, forever. The British made a handsome profit on the deal: they gave Mauritius £3 million, and obtained that the Americans waive off a debt of $14 million concerning an order for Polaris submarine missiles.

The archipelago was depopulated, the base built, and has been used in anger during the two Iraq wars as also for the Afghan war, and it has also reportedly been used in rendition operations under President George W. Bush. It is also a vital link for US military aircraft carrying out operations in Asia and the South China Sea. Its location enables US forces to extend their capabilities from Central and Eastern Africa and the Middle East to Central, South and South East Asia and the South China Sea. And, it is equally important to mention, Mauritius did get its Independence in 1968 despite the local opposition to it. But that is not the end of the sixties story.

In parallel with the surface rivalry going on between the US and the Soviet Union at that time, an intense competition was also going on between them in space. The Soviets had already, in 1957, taken the lead by sending the first man-made satellite, named Sputnik, into orbit around the globe; this device went on beeping radio signals as it circled the Earth, alerting the knowledgeable about the possibilities of using satellites for long distance point-to-point communications and broadcasts and for navigation.

President Kennedy, in his inaugural address in 1960, undertook that America would land a man on the moon and return him safely to Earth by 1970, and all concerned agencies were working furiously day and night to achieve that dream. Still, on 12 April 1961, the USSR stole a march by sending a man, Yuri Gagarin, into orbit around the Earth. But barely a month later, on 5 May 1961, American Alan Shephard repeated the feat, thus closing the gap between the rivals.

Since then, it is difficult to say who is ahead and who behind; competition finally gave way to cooperation with the International Space Station. But the Americans did land a man (Neil Armstrong) on the Moon on 21 July 1969 and did bring him back safely, a feat which the Russians have not engaged in. The American National Aeronautics and Space Administration (NASA) has turned to scientific missions, exploring Mars and other planets of the Solar System, and launching powerful telescopes into orbit expanding immensely our knowledge of the Universe. Two of those telescopes bear the names of famous astronomers: the Hubble Space Telescope, after astronomer Edwin P Hubble, and the Chandra X-ray Observatory, after astronomer Subrahmanyan Chandrasekhar. But, very sadly, after a sudden whim and no serious thought or deliberation at all, President Trump has recently ordered his military establishment to set up a Space Force for both defence and offence purposes. He first thought of it as a joke, he says, and then, later, why not? This is a most dangerous development for humankind as a whole. Are other nations going to stand idly by?

satellite-based navigation systems

Thanks to satellites, everybody can watch TV broadcasts from the remotest part of the globe. But perhaps the most significant uses of satellites today are for weather watch and for their application to navigation. The latter aspect of their use has become so important that advanced countries are now planning to do away with their most of their ground-based navigation facilities in favour of satellite-based navigation systems. The most widely known of the satellite navigation systems is the GPS. This consists of a constellation of 24 satellites (actually 31 inclusive of spares) in six orbits (four per orbit), beaming identification, ephemeris data (geometrical parameters of the orbit) and time to the ground, permitting suitably designed receivers on the ground to compute their positions.

The system is usable anywhere on the Globe, but as it is owned and operated by the US military, some governments are not inclined to rely solely on them for their air forces, airlines and other position-determination requirements. One never knows what can happen in time of war. The Soviet Union (now Russia) has developed its own global satellite navigation system named GLONASS; the European Union has practically completed developing its global satellite navigation system which bears the name Galileo; and the Chinese are building their global system which was known as Beidou, but which will in future be known by the name of Compass.

Less ambitious systems, which will only cover their countries and the immediate neighbourhood, are being built by India (under the name of Navic) and Japan (under the name of Quasi-Zenith). The navigation capabilities of all these systems is good enough for long-distance, en-route navigation, but need extra support for navigation in terminal areas for approach and landing. Each airport could provide its own support system but that would be expensive. The solution found is to offer support, or augmentation, systems that cover a wide area, even continents.

The US augmentation system is called WAAS (Wide Area Augmentation System); its area of coverage is North America and helps with GPS only. The European system is called EGNOS (European Geostationary Navigation Overlay System); its area of coverage is Europe, part of the Middle East, and most of the African continent; EGNOS will help with both GPS and GLONASS, the Russian system, besides Galileo. Mauritius is on the edge of the footprint area of the EGNOS satellite and there is little likelihood of its being available here. The Indian system is called GAGAN (GPS-Aided Geo Augmented Navigation system); it covers India and the Indian Ocean; it is certainly accessible in Mauritius.

The most widely used navigation system, freely available to everybody, is GPS. The US government incurs enormous costs in maintaining this service, first and foremost to meet its own military needs, but it cannot be denied that it is a great service to humanity. Firstly, there is the cost of making and launching the satellites themselves and replacing them when required, and very importantly, these satellites have to be serviced. They require constant monitoring, and the data they broadcast has to be constantly updated (up to three times a day).

In addition to a master-control station and a full back-up to that, they have to have a number of monitoring stations, remote tracking stations and ground antennas scattered around the globe at suitably located positions. Four of their most important stations are located at Cape Canaveral, Florida, at Ascension in the Atlantic, at Kwajalein in the Marshal Islands in the Pacific, and — you guessed it – at Diego Garcia, our own beloved atoll, for the Indian Ocean. Additionally at Diego, they have a giant telescope for detecting debris in space that could be harmful to satellites and astronauts. These, in my view, can be classified as service to science and to humanity in general.

Following the recent ruling of the International Court of Justice, efforts to recover Diego Garcia must continue apace. The stance of the present British Government that pursuing this matter further will adversely affect relations with Mauritius is unfortunate; we can hope that a different government will take a more sensible view. It is well-known that Jeremy Corbin, the Opposition Leader in Britain, does not share his Government’s views on Diego Garcia. Besides, with the present and all recent Mauritian governments pushing Creole above all languages, there is not much left for the average Mauritian in terms of relations with Britain, with the exception of football (as cricket still is with India). Even so, it is highly desirable that, in the negotiation process, an understanding is reached with the Americans to ensure that GPS operations are not affected in the least manner by whatever decision is taken.

* * *

Will an approach procedure based on the Indian GAGAN replace the present ILS procedure at SSRIA?

I seize this opportunity to raise a point that may be said to be only tenuously connected with the present subject.

If the Indian satellite-based GPS augmentation navigation system GAGAN is implemented in Mauritius, it will be possible to do away with the present ILS system when it comes up for replacement. That system now permits direct approaches into SSR International Airport from the west. The procedure was designed by me way back in 1971 in my position then as Director of Civil Aviation, after making certain changes in the parameters prescribed by the International Civil Aviation Organisation (ICAO). Strict application of the ICAO parameters would not have permitted an approach system at all, a situation not acceptable to me given the hazards that prevailed with the earlier system and the rapid rise in traffic that was taking place with Independence (with larger, heavier and faster jet aircraft replacing the earlier piston-engined propeller driven ones).

The alternative parameters of my system provided an equivalent level of safety to the ICAO system; the airlines I put it to readily agreed. Descent for landing would begin at Bigara, 10 nautical miles (n.miles) from Plaisance, on a 3.5 degree descent gradient. One of the measures I prescribed for safety was that pilots should ensure they keep ABOVE a given height while passing over Curepipe Point, a hill directly on the descent path, 8 n.miles from Plaisance. There were lots of delays and the system could only be implemented in 1978. In those days the system for calculating heights of aircraft in ICAO procedures was based on a “flat Earth” principle, a system still used today in Engineering Surveying in small areas (up to 20 km sq.). Using that principle, the height of an aircraft at Bigara, where the descent begins, would be 3950 ft. I therefore prescribed a horizontal approach height of 3900 ft from Flic-en-Flac, with descent starting at Bigara to ensure that aircraft captured the ILS descent angle beam from below.

Some pilots expressed concern about passing over Montagne du Rempart near Flic-en-Flac at that height. To allay their concerns, I prescribed an alternative horizontal approach path at 5000 ft from Flic-en-Flac with descent starting at Henrietta, 13 n.miles from Plaisance. During the subsequent months all pilots using the higher system unanimously said that during their decent they observed that at Bigara they were still slightly above 4000 ft and not below it as our calculations had indicated.

A basic tenet of science is that when the facts don’t agree with your theory, abandon or amend your theory – do not fudge the facts. Consequently, we abandoned the calculated height figures, and restored the horizontal approach path from Flic-en-Flac at 4000 ft to everybody’s satisfaction, and all arriving aircraft thereafter descended happily in a single smooth straight line down the ILS beam from Bigara to Plaisance. That was the situation when I left the country in February 1982.

In 1985, the Government asked ICAO to send an expert to vet the work I had done. He came – he was very competent, complying strictly with ICAO rules and procedures. He hit the height problem at Bigara as I had done earlier, and in his endeavour to comply strictly with ICAO rules (then still based on the “flat Earth” principle), and following a piece of very contorted logic in my view, he arranged for aircraft to disregard the ILS beam between Bigara and Curepipe Point. He introduced a kink in the descent path, forcing aircraft to descend TO the flat-Earth height at Curepipe Point, instead of remaining ABOVE it. This actually brings the aircraft below the ILS beam and closer to the ground than necessary at that point by nearly 60 ft. The ground there is not too far below the aircraft at that point, or at any other point on that approach. I was informed about the proposal and disagreed with it but could not do anything about it as I was abroad, no longer in the Government Service, and extremely busy with my own work.

I subsequently came to the conclusion that the discrepancy in aircraft height noticed at Bigara was probably due to the spherical nature of the Earth’s surface, and worked out an approximate formula for the discrepancy as 0.883×d² ft , where “d” is the distance in n.miles, usable for distances of up to 20 n.miles.

These days aircraft are guided by pre-programmed computers which do not feel the pain of a kink. Even so, it is well established that a smooth, straight descent path is safer than one with a kink. To cap it all, ICAO has woken up to the fact the Earth is not flat but spherical. In the latest edition of its manual on the subject, it has prescribed new figures for heights of aircraft on descent paths at various angles, putting a question mark on the height of aircraft prescribed at Curepipe Point.

Another concern is that a procedure for satellite navigation systems published by the authorities subsequently follows the same kinky system. It is doubtful whether GAGAN will bring any improvement to what currently exists, unless the approach procedure is returned to what it was when I left it in 1982. Let us hope and pray that this matter never comes up in an air safety incident at Plaisance in future.


* Published in print edition on 24 May 2019

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