Business Opinion: The latest shot has been fired in the battle to keep Aer Lingus grounded. Within days of its completion, a confidential review of the airline's pension costs and liabilities made its way into the public domain, (helped on its way by this paper it must be said).

The report by Mercer is manna from heaven for those opposed to the sale of the national airline.

The worst case scenario - and the one most likely to be taken up by opponents of the flotation - is that there is a potential hole of €433 million in the scheme, which would knock the stuffing out of the airline's balance sheet were it reflected in the accounts.

Mercer do add a number of caveats to this assessment. The main one being that they did their sums on the basis of what they believe is Aer Lingus's share of the liabilities and assets of the pension scheme it shares along with the Dublin Airport Authority and other state bodies.

The second is that the worst case scenario assumes that Aer Lingus continues to increase benefits in line with inflation and other factors.

If, for the sake of argument, we assume the worst case scenario is the reality, what does it mean for the possible sale of Aer Lingus?

The short answer is not very much. If you were to draw up a list of the top 10 factors that will influence the sale process - assuming of course the Government pushes the button - the pension scheme would be closer to the bottom than the top.

It will have some accounting consequences. At present Aer Lingus avails of an accounting convention that means it only has to show in its accounts the amount it actually pays into the scheme each year (around €5 million) and does not have to reflect the deficit, or surplus for that matter, in its accounts.

This would have to change if the airline had its own scheme, rather than sharing in the Irish Airlines scheme. Under various scenarios explored by Mercer, this could mean having to reflect a deficit in the scheme of up to €475 million and a charge to the profit and loss account of up to €22.7 million.

Reflecting this would have knocked the stuffing out of last year's accounts, when the company made a profit of €1.14 million (after restructuring costs of €104 million) and had net assets of €366 million.

But the reality is that plenty of companies on the Irish Stock Exchange would see their balance sheets knocked for six if their pension liabilities were reflected in them. Going forward many of them will have to do this, as new accounting standards that require this come into force, but at present most companies choose to have a note in the accounts indicating what would be the consequences of reflecting the pension deficit.

The net effect of all this is to add another twist to the already complex task of extracting a company's real financial position from its published accounts. This in turn adds another dimension to the black art of valuing companies and this is the fundamental exercise that will be performed if and when Aer Lingus is sold.

In short, this means that Aer Lingus will have to reflect the pension issue in its accounts but this will not in itself scare off investors. They will want to see two things, certainty about the liabilities and evidence that a plan is in place to tackle the problem.

It's worth noting in this connection that the last two substantial Irish companies to come to the market, Eircom and C&C, both have significant pension fund deficits.

But, having said all that it is naive to think that the pension deficit will not be a big issue in the debate over the future of Aer Lingus.

The airline's unions can be expected to use it as an argument for why the company should not be sold. The fact that the deficit is theoretical and a problem common to many successful businesses will not make much of a counter argument to allegations that the Government is washing its hands of a state company which in effect owes its employees millions.

At a minimum it will become a bargaining chip in the negotiations that will lead to the unions naming their price for supporting the sale.

But it is also worth noting there are some very senior figures in Government who would appear to be looking for a reason not to sell Aer Lingus. The pension deficit is as good an excuse as any other.