Trade union Siptu is seeking urgent clarification from its financial advisers on how Aer Lingus workers will benefit from a planned €110m pension rescue deal.
Siptu has asked the Irish arm of US firm Towers Watson to specifically examine how much each individual at Aer Lingus who is a member of the troubled Irish Airlines Superannuation Scheme (IASS) will receive from a planned capital injection that the airline has offered to shift members of the scheme to a new defined contribution programme.
Earlier this year, Aer Lingus pledged to put €110m into a new defined contribution scheme for active members of the IASS, and another €30m into the scheme in respect of former employees who are deferred members of the IASS, as part of a Labour Court recommendation.
The IASS has a deficit of around €800m.
But the plan was thrown into disarray when the Pensions Board rejected the proposed funding arrangement, which would also see the DAA stump up €60m for a new defined contribution scheme.
The trustee of the IASS told unions last week that the fund's position had deteriorated further and that cuts in benefits of up to 25pc for future retirees could be required.
Aer Lingus insisted last week that the money it offered remained sufficient.
Siptu has asked Towers Watson whether actuarial assumptions used in May to determine what level of capital funding would be required from the airline to help fund the new defined contribution scheme were now outdated to the extent that additional funding would be needed.
Unions, the airline and the DAA have until Friday to submit comments on the proposals set out last week by the IASS trustee. Aer Lingus has urged the IASS trustee to put forward a proposal to the Pensions Board "as soon as is practicable".