Aer Lingus faces the possibility of industrial action next week after the airline threatens to remove cabin crew employees from the payroll if they fail to comply with new rosters being introduced on Monday.
There has been disagreement between management and cabin crew over the rosters for months - with cabin crew engaging in a work-to-rule since 12 October.
The new rosters form part of the implementation of the Greenfield Cost Reduction programme introduced by the airline last year.
All grades apart from cabin crew have fully implemented the Greenfield proposals for their sectors.
In a letter to individual employees, Director of Staff Relations Sean Murphy says that the new rosters comply with the Greenfield Cost Reduction agreement which has already been accepted by cabin crew and contain all the necessary changes to deliver the productivity commitment of 850 flying hours.
However, the cabin crew union IMPACT has said that the rosters do not comply with a subsequent arbitration agreement.
Contacts at the Labour Relations Commission this morning failed to resolve the row - and it is understood the Commission sees no value in a further intervention at this point.
In their letter to staff, Aer Lingus accuses cabin crew of continuing to obstruct implementation of the productivity changes negotiated in the Greenfield agreement - one year after it was finalised.
The letter says it must now adopt measures to protect the interests of the company, its shareholders, wider staff groups and our customers.
The company reminds staff of their contractual obligations and the consequences of not complying with those obligations.
The letter states: 'In light of the above, we advise again that we expect you to comply fully with all rosters published. Failure to do so will put you in breach of your contract of employment. Aer Lingus will not accept staff refusing to carry out some or all of their contractual duties. A continued refusal will result in you being put off duty and removed from the payroll.'
However, the airline also says it will reintroduce all staff travel privileges from 17 January in anticipation that staff work their published roster fully.
In a responding letter, IMPACT accuses the company of theatening staff and warned that its current work to rule will remain in place until the dispute is resolved to members' satisfaction.