According to reports, they told workers last week of plans to shut the pension scheme to new recruits, a move that should gradually bring the deficit under control. The bottom line is that a lot more of the cash raised from selling the airline could be spent on new aircraft rather than propping up workers' pension entitlements.

It is a strategy that has worked elsewhere. British Airways closed its main pension scheme to new members three years while allowing existing staff to carry on building benefits.

Other companies acted even earlier so that their pension obligations now appear manageable.

AIB pulled the plug almost a decade ago so that anyone joining the bank after December 1997 is automatically excluded from the main pension scheme. Instead they join a defined-contribution scheme, which is no more than a tax-efficient savings plan into which the bank and its employees make contributions.

The result is that AIB no longer has to sign a blank cheque every time a new body is added to the payroll, guaranteeing them a pension for life linked to earnings while working. Instead it has shifted the risk to its employees, who must save enough over their working lives to make ends meet during retirement.

As more employers buckle under the strain of providing guaranteed pensions for workers who can be expected to live longer and longer, the shift to defined-contribution pensions is increasing.

"It's an issue that more and more companies are taking a critical look at, " says Tom Geraghty, head of Mercer Investment Consulting. "Pension deficits have become the tail that is wagging the business dog at many companies.

A lot have already closed their schemes to new members to help minimise the problem."

On paper, the problem does not look too bad. Pension Board statistics show that workers in defined-contribution schemes are still a minority, outnumbered two to one by people who still enjoy the benefits of guaranteed pensions. But a different picture emerges once you strip out public servants, whose goldplated pensions are underwritten by the taxpayer. Now you see an even split between defined-benefit and definedcontribution schemes in the private sector, with the balance tipping inexorably in favour of the latter.

Mercer has attempted to get a handle on the extent of the slide in an annual survey of employers which still offer defined-benefit pensions.

Last year it found that 60% had either watered down the benefits on offer or were planning to do so in the near future.

For most companies, this means pulling down the shutters on new employees; based on current trends, Mercer predicted that one-third of all defined benefit schemes will be closed to new members by 2007.

Launching last year's study, Anne Kershaw, senior actuary at Mercer, said: "This trend shows that employees who move job are less likely to be included in a defined-benefit scheme with their new employer. Defined-benefit pension schemes will inevitably become the preserve of older, long-serving employees only."

Faced with a choice between forced cuts in benefits across the board, or sacrificing the entitlements of new recruits to protect the pensions of existing workers, the trade unions have generally picked the path of least resistance.

This abandons future generations of workers to a very uncertain retirement. Not only will their pensions not be guaranteed, their employers are also being more stingy, contributing far less to defined-contribution schemes that they would have to pump into a traditional, defined-benefit pension.

According to Mercer, payments to defined contributions average about 10% of wages, with a roughly equal split between employee and employer contributions. This falls far short of what most people would need to secure a comfortable retirement, with Mercer suggesting that a contribution target in excess of 20% of wages would be more appropriate.

Even those workers lucky enough to hold on to definedbenefit entitlements should not feel too smug. Mercer's 2005 survey found that 10% of schemes were thinking about asking members to dig deeper to pay for these benefits.

Worse still, 5% of schemes have taken by nuclear option by freezing the pension scheme even for existing members and an equal number are thinking about following their example.

This should give social affairs minister Seamus Brennan something extra to worry about when he launches pensions action week tomorrow, aimed at coaxing more people into thinking about how they are going to pay for retirement.