Pilots at Aer Lingus have submitted a pay claim for parity with their counterparts at British Airways. The claim - for rises in excess of 30 per cent in some cases - is in addition to increases in the latest national agreement and a separate rise last year.
The claim could have serious implications for plans to float the airline because discussions on pay at all levels in the company are closely linked to a proposed Employee Share Ownership Plan (ESOP) and a separate negotiations on its pension scheme.
Resolution of these three issues is seen as crucial before the Government can proceed with its flotation plan.
While senior figures in Aer Lingus maintain the airline could be floated in November at the earliest, this is seen as increasingly unlikely by people familiar with the thinking at the trade unions in Aer Lingus.
One person conceded that the pilots' demands could lead to a series of counterclaims from workers on other grades at the airline, whose claims are significantly lower than that of the pilots.
Managers at the company are believed to be unhappy with the latest claim because they say pay should be set in accordance the company's individual performance and not that of its competitions.
But the Irish Airline Pilots Association, which is affiliated with IMPACT, has lodged the claim on the basis that its members should receive the same pay as others in the OneWorld alliance.
The claim is in its initial stages only - and has yet to be formalised - but one person familiar with the situation said it could amount to even more than 30 per cent in some cases.
For example, a British Airways long-haul pilot based in London might earn the equivalent of £150,000 annually on routes to Australia, a Dublin-based long-haul pilot on Aer Lingus's Los Angeles route might earn £80,000-£90,000 each year.
Legislation to allow the flotation has yet to pass the Dail stage of the Oireachtas.
And while discussions on an ESOP - to increase the stake owned by Aer Lingus workers to 14.9 per cent from 5 per cent - are well-advanced, no agreement has yet been reached on the price workers will pay for that stake.
One suggestion by a senior figure is that shares granted in the scheme will be effectively priced at a 40 per cent discount to the prospective value of the airline when floated.
This tallies with the view that shares in the general offering will be priced at favourable rates by the Government, which it will be keen to ensure demand but conscious of the poor performance of Eircom's stock.
It is unclear why pilots should choose to claim such a significant rise at this stage. One person said it could not be ruled out that pilots were attempting to delay the flotation, although a trade union figure said this was not the case.
A rise to pilots last year granted increases of 3-6 per cent to people at various grades.