Staff at Irish airline Aer Lingus and the Dublin Airport Authority (DAA) have voted to take industrial action if their employers do not act to protect their pension pots.

The workers, who pay into the Irish Aviation Superannuation Scheme (IASS) pension pot, are concerned their savings will be forfeited if their employers do not plug the scheme’s €700m funding black hole.

Six unions, SIPTU, Impact, Mandate, TEEU, Unite and UCATT, have balloted members to take action if any negative changes are forced through. Protests could include an overtime ban, working to rule, non-cooperation, limited work stoppages or withdrawal of labour.

Aer Lingus admitted that as much as two-thirds of the deficit is attributable to its employees or former staff but the firm rejected claims it was their responsibility to cover the shortfall. The employer has said it was required to pay the current employer contribution rates but not to increase this amount.

The Labour Relations Commission has been tabling talks to solve the dispute but unions are concerned that the employers involved will pull out of the talks forcing the pension trustees to wind up the scheme to the detriment of savers.

Irish Congress of Trade Unions' industrial officer Liam Berney said: “The result of the ballot should send a clear message to both companies [Aer Lingus and DAA] that staff are determined to secure their pension entitlements and are prepared to act to ensure this is the case. It is now up to both companies to come forward with proposals that meet the expectations of members of the IASS.

“The unions are available for meaningful negotiations. However, the time has come for the companies to put forward realistic proposals that are capable of being given serious consideration.”

In its in its first half yearly results for 2012 published at the end of July, Aer Lingus said: “We note the recently concluded union ballot to seek a mandate for industrial action in the event that the funding shortfall in the IASS is not addressed. Notwithstanding this ballot, the [airline] group believes that the process being conducted under the auspices of the Labour Relations Commission continues to represent the best opportunity for the resolution of issues arising from the shortfall in the IASS.”

Aer Lingus is currently fending off a takeover by Ryanair amid claims that its rival’s takeover plans would be “highly destructive”. The company also said that the legal costs in bringing its defence against the bid to the European competition authorities have cost millions preventing the firm paying shareholder dividends.