SIPTU workers have accepted the Aer Lingus rescue package proposed by the Labour Relations Commission. The 81 per cent vote by cabin crew, clerks and operatives means the State airline, which is seeking 2,026 voluntary redundancies, has passed a significant hurdle in its restructuring plan.

But uncertainty still surrounds the plan's fate because pilots, represented by the IMPACT union, have threatened strike action.

The company's chief executive, Mr Willie Walsh, has warned pilots that compulsory redundancies will be imposed in January after fewer than five of the 531 who work for Aer Lingus signed up for the voluntary package. That stance was repeated yesterday by an Aer Lingus spokesman.

The result of a vote on the package by all members of IMPACT, which also represents middle managers and cabin crew, will be known today.

A proposal to expand the employee share option plan (ESOP) at the airline was put to the IMPACT workers in that vote. That element of the rescue will be voted on separately in the new year by SIPTU workers.

There were nine elements to the "central agenda" package endorsed in the vote by 2,255 SIPTU staff - or 64 per cent of the union's workers in Aer Lingus.

The deal includes the suspension of pay increments and increases under the Programme for Prosperity and Fairness (PPF) and the cancellation of a day in annual leave.

However, catering and aircraft cleaning operatives rejected work practice changes which the union said were accepted by a significant majority of their colleagues. SIPTU said it would discuss these issues with Aer Lingus management in the coming days.

The vote was welcomed by Minister for Public Enterprise Ms O'Rourke and management at the airline. An Aer Lingus spokesman said the plan was the minimum required to return the airline to profit in 2003.

However, SIPTU still has a veto over the rescue plan because of the separate vote on the ESOP. The Government has agreed to increase the 5 per cent held by workers to 9.9 per cent as part of the rescue package. As part of that deal, however, retrospective payments foregone in the suspension of the PPF will not be paid. SIPTU is unhappy with that element of the package, so it will be subject to a new vote.

While the IMPACT vote is another crucial element of the rescue package, the key test will come when Aer Lingus decides what to do about the poor take-up by pilots of the package. Sources say the difficulty is compounded because pilots cannot be redeployed to other posts in the company.

Pilots argue that they have foregone a £20,000 (€25,400) pay rise. In addition, they say a maximum lump sum of £50,000 contrasted with possible lump sums of £180,000 if pilots were offered the same formula as applies to other staff. The company said it could not offer more.

So far, about 1,600 Irish staff have signed up for the voluntary package, which was negotiated after the company said its entire future was in jeopardy due to the global aviation collapse after the September 11th terrorist attacks on the US.