Thousands of Ulster Aer Lingus passengers were today facing possible travel chaos as pilots prepared to strike after being threatened with suspension for refusing to train staff at the airline's new Belfast base.
The pilots were today due to meet to plot their course of action after negotiations with management broke down without agreement.
The Irish Airline Pilots' Association has not ruled out a strike - a move which would create major chaos for the Dublin-based airline's 15,000 daily passengers, including thousands of passengers from Northern Ireland who travel to Dublin Airport each day to avail of its services.
Aer Lingus, which is planning to start services from Belfast International in December, said that all pilots face immediate suspension from the payroll if they continue to refuse to train new pilots in Belfast.
IALPA said it considers the threat a serious escalation in the dispute over pay and conditions at the new base.
It said it is meeting later today to consider its response, although it said it is committed to finding a solution to the difficulties.
However, it has also warned that its policy of non-cooperation with the establishment of the Belfast base remains in place.
The company's 500 pilots have opposed its plans to recruit pilots for its new base in Northern Ireland since those plans were announced in early August.
And IALPA previously instructed all pilots to refuse to cooperate with the training and recruitment of the new pilots.
The existing pilots are not happy at the terms and conditions being offered to newly recruited pilots who will operate out of the province.
Under the company's proposals, Republic-based pilots appointed to Belfast will be presented with two options.
Those transferring permanently must immediately move to Belfast terms and conditions, and must also leave their guaranteed pension scheme and join a new defined contributions scheme in Northern Ireland.
The other option is to move to Belfast on secondment of three to five years, during which time the pilots would be on Belfast terms and conditions, but would revert to Republic terms if they moved back, and would also retain their guaranteed pension rights and service. In either scenario, staff would maintain their original date of entry.
It also emerged that the industrial relations chaos may not be confined to Aer Lingus pilots.
Its check-in staff, baggage handlers and administrative workers could join the picket line.
Siptu, the union which represents non-cabin crew staff, said it was considering industrial action over a pay freeze for employees.
Meanwhile, Michael Landers of trade union Impact, the umbrella group for IALPA, insisted the instruction not to co-operate with recruitment still stood.
"If a pilot does work on recruitment we will treat them as having breached the rules of the union," he said.
Usually unions give one week's notice in advance of any strike, but Mr Landers said this would "not necessarily happen" in this case. " We're not putting any constraints on what we might or might not do at this stage," he said.
Sources at Aer Lingus said the company thought some form of industrial action was "likely" in the coming days.