Aer Lingus management and Siptu trade union representatives have reached agreement on changes to work practices due to be introduced tomorrow morning.
The deal means that the threat of strike action at the national airline has been averted.
In a joint statement released tonight the two sides said that a deal had been struck after almost 34 hours of continuous talks. The deal is subject to a successful ballot of Siptu members.
Aer Lingus Chief Executive Dermot Mannion said: "We have agreement on the implementation of productivity and cost-cutting measures with Siptu and we await the outcome of their internal ballot process.
"Nothing will be implemented until the ballot is completed."
Siptu National Industrial Secretary Gerry McCormack said: "We accept there has been genuine commitment by both sides to reach an agreement and the process has protected Siptu members' interests and also prevented disruption to Aer Lingus passengers."
The talks have been in session since Friday night in an attempt to resolve a dispute over the implementation of changes to work practices and in an effort to avert strike action.
The union had warned that unilateral implementation of changes in work practices would result in a protracted dispute after Aer Lingus management warned staff that they would be suspended from tomorrow unless they co-operated "unreservedly" with the changes.
The sides came together on Friday after management invited union representatives to resume negotiations on Thursday night following a union warning of a "long and bitter" dispute.
The airline wants 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.