Cabin crew involved in a pay dispute with Aer Lingus have escalated a work-to-rule begun last month.
The airline, however, says it expects no disruption to services today or during the weekend, and has advised passengers to check in for flights as normal.
It said it had withdrawn cheap travel concessions from staff involved in the dispute and their families, but said this was not a response to the most recent escalation in the dispute.
From this week the 1,000-plus staff involved in the dispute, who are members of IMPACT, have been working a strict 35-hour week.
Under flexibility arrangements crews normally work up to 78 hours a fortnight.
Ms Christina Carney, of IMPACT, said staff were paid for the 35 hours only, even when the extra hours were worked. This showed the degree of flexibility and co-operation cabin crews had been providing for years.
A spokesman for Aer Lingus, however, said staff were paid for all extra hours worked.
He said the company had withdrawn travel concessions because it felt it would be inappropriate to provide them to staff involved in a dispute which had caused disruption to the public.
Some flights have been cancelled and others delayed since the work-to-rule began to have an impact at the end of last month.
However, the airline has described the disruption as minimal, and has hired aircraft and crews in some cases to ensure services are maintained.
The union's action is in response to the company's refusal to pay members an outstanding 4 per cent increase under the Programme for Prosperity and Fairness.
The two sides are in dispute over the level of increased productivity required for staff to qualify for the payment.
Talks in the Labour Court ended last week without agreement. Both sides say they are available for further discussions.