Siptu has served strike notice on Aer Lingus this evening over what it says is a company decision to "unilaterally downgrade" the working conditions of its employees.
National industrial secretary Michael Halpenny claimed strike notice was issued because the airline is coercing temporary employees to sign employment contracts offering significantly worse pay and conditions, by refusing to extend current employment for contract staff beyond January 31 stnext year.
By the end of January 2008, permanent staff positions and temporary contract extensions will be subject to agreement to new work terms and conditions of less pay for more hours, Mr Halpenny said. Many of the staff affected are "vulnerable migrant workers" with limited English language skills, he added.
Strike action will consist of rolling four hour work stoppages throughout Tuesday, November 20 thand Friday, November 23rd at Dublin, Cork and Shannon airports.
Siptu is also seeking support from the Irish Congress of Trade Unions (ICTU) and has called for an "all-out picket".
Mr Halpenny said: "This latest attack on our members comes on the heels of a pay freeze imposed by the company simply because our members have not agreed to allow the company to cut their pay and conditions.
"The justification for this relentless attack on the living standards of workers on, or near the average industrial wage, is that Aer Lingus rates are 'not competitive' in aviation sector terms," he said.
"The methodology on which this claim is made has never been disclosed and the only airline that has labour costs significantly lower than Aer Lingus is Ryanair, which outsources so much of its work that comparisons with its direct labour costs are meaningless."
Aer Lingus, which has been battling with unions to cut overheads since its privatisation last year, averted flight disruptions in October after reaching a last-minute deal with pilots over a disputed new base in Belfast.