Staff at Aer Lingus and the Dublin Airport Authority are facing significant cuts in their pension entitlements.
They will also have to work for longer under a proposal outlined by the pension scheme trustees.
The Irish Aviation Superannuation Scheme - which covers workers from both companies - currently has a deficit of well over €700 million.
A proposal to address that deficit was rejected by the Pensions Board during the summer.
The trustees told union and management representatives today that their revised plan would involve a 12% cut in benefits, extended retirement ages in line with changes in the State pension age, and mandatory changes in how the payment is split between lump sums and ongoing payments.
One source gave an example of a worker who would originally have expected a company pension of €52,000 - plus the State pension of €12,000 - could end up receiving a final pension below €35,000.
Union sources voiced serious concern about the extent of the cut in pension entitlements.
It is understood the trustees have asked employers and unions to respond to the revised plan by 18 October.
Both management at Aer Lingus and the DAA, as well as the Government, are anxious to resolve the pensions issue as soon as possible.
The deficit is viewed as an impediment both to the sale of the Government's 25% stake in the company, and to future alliances or mergers that might facilitate the growth of the airline.