Mr Adcock is in Montreal attending the ICAO celebrations.

'I find it quite amazing that they were able to reach a consensus on a convention which is substantially unchanged until this day,' he said.

'It is fair to say that the real development of civil aviation as we know it has grown out of the meeting in Chicago in 1944 and that meeting is very much a child of World War II.

'ICAO was not the first attempt to co-ordinate air services on an international basis but it is the most important and far reaching.

'There were attempts right after World War I but they did not have a lasting effect.

'The circumstances of the day were particularly interesting as far as the attitudes of the individual participants. There were three main blocks.

'The Americans had the advantage of an air transport industry that had been stimulated greatly by the need for air transport to support the war effort, as well as the fact their domestic civil air transport system had been able to develop during the war years without external interference.

'They had a flexibility to develop their aircraft, their systems, their handling of aircraft commercially for reservation systems and ramp handling for example. They were, for air transport, some way in advance of the rest of the world.' In the circumstances, it was hardly surprising that the US supported open skies and free access to markets, Mr Adcock said.

'The second big block was based on the Europeans. For the most part, the air transport industry had been totally wiped out by the war.

'It was almost like starting from scratch, with undeveloped airports and techniques for handling air transport.

'They were also highly individualistic. The European attitude tended to be more restrictive and required prior permission for any operation,' he said.

The Russians were not prepared to agree to over-flights, he said.

The ICAO convention also made provision for the establishment for Standards and Recommended Practices, or SARPS. These were codified in the form of a series of 18 annexes.

Annex 1, for example, dealt with personnel licensing and Annex 18 referred to dangerous goods. Additional annexes would be created depending on needs.

Among the most important things for Hong Kong and air transport was technical standards.

'It only works if individual governments are prepared to work together,' Mr Adcock said.

'They do this through a series of committees, panels and planning groups, established under the aegis of ICAO, which provides for standardisation of navigation systems, operating standards, communications, air traffic control, airworthiness and the like.' Mr Adcock said that, for Hong Kong, ICAO's co-ordination was critical.

'If we did not have this arrangement, it would mean every time a new airline wanted to establish a service into Hong Kong, we would have to negotiate the standards that were applied to that aircraft. Also, we would have to make individual arrangements for communications,' he said.

On December 7, 1944, representatives from 52 countries gathered in a crowded Chicago hotel to lay the foundations for the ICAO.

The conference created a multilateral convention, three agreements and a standard form of bilateral agreements.

Agreements defined the five freedoms of the air and provided the rules that enabled international air transport to be conducted safely across languages, countries, and continents, and also allowed flexibility to accommodate rapid technological changes.

ICAO has forecast that, by 2001, passengers numbers will reach 1.8 billion. This represents about 30 per cent of the world's population.

With headquarters in Montreal, ICAO has a membership comprising 180 sovereign states which support a 1,200 air carriers.