Aer Rianta boss John Burke was at it once again this week, telling a gathering of chartered accountants how badly Aer Rianta needs a stock market flotation to help fund its investment programme over the next few years. Mr Burke poohpoohed the idea of selling off Aer Rianta in a trade sale or of forming a strategic partnership.

Current Account has previously been a critic of Aer Lingus's flotation plans and has similar feelings towards a flotation of Aer Rianta. Quite what Aer Rianta's attractions are to institutional investors in the current investment environment are unclear to say the least. Ownership of three Irish airports and interests in two airports in the UK and Germany, with no duty-free sales, is not a compelling investment, especially if the State insists on hanging on to a majority of the Aer Rianta shares.

Investors in European airports have plenty of options at the moment, from BAA and TBI in the UK to a batch of state-owned airports in the euro zone which have already been partially sold and which are due for full privatisation.

Vienna, Copenhagen and Rome airports are still owned more than 50 per cent by national governments or local municipal authorities, but these stakes will fall in the current year with the Italian government expected to sell off all its remaining stake in Rome airport.

That is a lot of airport equity coming on the market in the year before Aer Rianta is tipped to be floated.

Those keen on an Aer Rianta flotation might do well to read a recent Merrill Lynch review on European airports which does not suggest that Aer Rianta will be a particularly attractive prospect.

For a start, Merrill says that passenger growth is polarising towards major regional gateways or those airports prepared to accommodate low-cost airlines with discounted charges.

Aer Rianta hardly fits into either of these two categories, and definitely not the latter where low-cost traffic through Ryanair is unlikely to be a major growth area for Dublin Airport.

Merrill also warns that secondary hubs will see growth falter if they are unable to establish themselves as regional gateways for airline alliances.

If institutional investors are looking for euro zone airport exposure, what attractions does Aer Rianta have over those of Aeroporti di Roma with its likely €2.1 billion valuation, Copenhagen and Vienna.