The Commission for Aviation Regulation has decided to change the system which governs the allocation of landing and take-off slots at Dublin Airport.
But Ryanair, which has consistently opposed any change, has said it will challenge the decision in the courts.
The regulator said that for the Summer 2007 season, the airport would be a 'co-ordinated' rather than a 'scheduled facilitated' airport. The former system involves the appointment of an independent co-ordinator to allocate slots, while the latter allows airlines to agree slots on a voluntary basis.
Ryanair overturned the previous introduction of a co-ordinated system after a court challenge last year. Aer Lingus and the Dublin Airport Authority have welcomed the decision.
The regulator then commissioned a capacity assessment of Dublin Airport, which found that peak demand this summer would exceed capacity. The Jacobs Report also warned of 'significant delays'.
* Ryanair is to be included on the Nasdaq 100 index on Wall Street from the opening of trading on Wednesday. 38% of Ryanair's shares are traded on the Nasdaq, according to the airline.
