Cabinet has agreed to put out to tender a contract for independent consultants to review the air traffic congestion at Dublin Airport which has risen significantly.
The airport hit a record 25 million passengers last year and looks set to reach 27m this year.
The review will include the possibility of a third terminal.
Cabinet also approved a proposal by the Minister for Transport Shane Ross to appoint the Irish Aviation Authority as the competent authority to regulate noise levels at the airport.
The move relates to an EU directive on aircraft noise.
The Dublin Airport Authority has had planning permission since 2007 for a third runway, which expires in August 2017.
It has stated it wants to remove two conditions restricting the use on a third runway at night.