Splitting airport traffic between two airports would diminish Dublin's attractiveness as a traffic hub, according to Dr Aisling Reynolds-Feighan of University College Dublin.

Examining the impact and implications of the deregulation of the European air transport sector in the latest issue of the Irish Banking Review, Ms Reynolds-Feighan argues that concentrating air traffic at a single airport in Dublin is the best way for Ireland to continue to benefit from deregulation.

Air transport liberalisation has resulted in an average annual increase of 13.9 per cent in passenger numbers through Dublin, Cork and Shannon airports through 1993 to 1998.

It has made Dublin a large traffic hub with enhanced accessibility for people and goods to and from regional airports, all British regions, European centres and the long-haul routes, she says.

Arguing that this accessibility is important for the economy's continued growth, Ms Reynolds-Feighan maintains that it would be diminished by splitting the traffic between two airports in Dublin.

But she warns that if Ireland is to continue to benefit from the deregulation of European air transport, the issues of airport capacity management and pricing and of direct access to the main global air transport networks must be carefully evaluated.

On the Dublin-London route, Ms Reynolds-Feighan said Ryanair's arrival contributed "in no small way" to making it the busiest air route in Europe.

But referring to low-cost carriers, she said they had had limited regional impact and tended to focus on under-utilised secondary airports close to major hubs.

While the range of fares available has increased since 1992, she found that, unlike the US experience, widespread across-the-board fare reductions had not materialised.

In addition, she found an increase since 1994 in departure delays at European airports.

On Aer Rianta, Ms Reynolds-Feighan listed several options for the Government: sell the Dublin, Cork and Limerick airports either as a single entity or separately, or "unbundle" (split up) the infrastructure and passenger/freight services roles and permit competition from other providers of passenger/freight services.

The last of these options would allow the infrastructure to remain in public ownership while introducing competition into the service roles.

Whichever option is chosen, Ms Reynolds-Feighan says the management and provision of the infrastructure must be prioritised if Ireland is to continue to benefit from a single air transport market.