Travellers were today warned of possible delays after talks to resolve a dispute involving Irish air traffic controllers failed.
With employees at Dublin airport refusing to work overtime, the Irish Aviation Authority (IAA) has referred the matter to the Labour Relations Commission.
Impact officials described the negotiations as "largely positive," with progress on some issues, but said "significant differences" remain.
"Air traffic control staff will continue to work their normal shift rotations, but will not volunteer for overtime until further progress is made on the issue of staff shortages," the union said.
Workers took unofficial action banning overtime and claimed that a recruitment freeze had been in place since the September 11th attacks in New York more than six years ago.
Staff insisted they will continue to work normal shifts, but their overtime ban risks disrupting flights through Dublin.
The IAA said they had asked the Labour Relations Commission to look into the dispute urgently and that normal service was being operated at Dublin airport.
"However, continuation of the unofficial action by controllers could lead to delays, because, in the interests of safety, the authority would have to restrict the number of aircraft using Dublin's airspace," the IAA said.
