Tens of thousands of air passengers face possible widespread disruption next week as a result of two disputes at the State's main airports.
Air traffic controllers yesterday served notice for a one-day stoppage next Thursday, in a move the Irish Aviation Authority (IAA) said would ground all flights into and out of the State.
An estimated 90,000 passengers will be affected if the air traffic controllers' dispute goes ahead. International air traffic using Irish airspace would also be hit by the row, and passengers on some transatlantic services could face longer journeys.
Air services in some areas could be disrupted from Tuesday as the air traffic controllers introduce an official overtime ban as part of a row over staffing levels, overtime and rosters.
The Labour Court has invited the parties to talks on Monday in a bid to avert the dispute.
Separately, up to 20,000 Aer Lingus passengers could face disruption from early next week in a row between the airline and trade union Siptu over work practice reform.
Aer Lingus last night warned about 1,800 Siptu members, mainly ground operation staff, that they would be suspended from the payroll from Monday unless they co-operated "unreservedly" with new work practices.
As part of a new flexibility and productivity plan, the company is seeking to introduce new rosters with shifts of varying lengths, earlier starting times and the freedom to move staff between duties - for example from check-in to boarding - in the course of the shift.
The airline said the reforms were necessary as part of an overall €20 million cost-saving initiative.
It said that once the reforms were in place it would pay increases to staff that are due under the national agreement.
In a letter to workers, Aer Lingus management said it would implement the changes unilaterally if agreement was not reached with Siptu by this weekend. It would expect staff to co-operate with the reforms and warned that it was a condition of employment that they comply with instructions.
"It is important that you understand that if you fail to unreservedly engage in your full range of duties as may be instructed and requested, you will be suspended from the payroll," the letter said.
An Aer Lingus spokesman said the company was not prepared to keep on talking after the deadline of Friday, either at local level or through third parties. He said the airline had been through all the industrial relations machinery in the State over the past 14 months.
"The union seemed to think that if we kept on talking we would run out of steam, but we have just run out of patience," he said.
A Siptu spokeswoman said that if staff were suspended the union would "react accordingly".
Siptu yesterday accused Aer Lingus of seeking to rewrite the flexibility agreement. It said that "industrial action will only be activated if the company goes ahead with its threat to unilaterally introduce new, or changed, conditions of employment next week".
The trade union Impact said yesterday that the dispute involving air traffic controllers was over a chronic shortage of staff in this area.
However the Irish Aviation Authority said that the row was about "enhanced overtime/call in payments and rosters".