The Knock-Dublin and Derry-Dublin routes . . . operated under a combined contract . . . are the two most heavily supported routes, with each passenger subsidised by almost 190 for a return journey.

That subsidy on the Knock route is equivalent to the per-passenger cost if the government hired a taxi to carry three people on the 250-mile return journey.

However, the subsidy on the KnockDublin route has dropped dramatically in recent years.

In 2003, the government subsidy on a return trip between Dublin and Knock was a staggering 557 and as recently as last year, the subsidy for a return journey to the Co Mayo airport was almost 380 . . . twice the current subvention.

The figures, released by transport minister Martin Cullen in response to a Dail question from Fine Gael's Phil Hogan, show a fall-off in the number of passengers on the Knock route.

In the month of January 2006, 631 passengers flew between Knock and Dublin . . . an average of just 20 a day and just over half the number that used the service in the same month 12 months earlier.

There was a similar drop-off in passenger numbers on the route for all months in the second half of last year, when compared with numbers in 2004.

After Knock and Derry, the highest subsidised routes are Donegal and Sligo . . . also operated under a combined contract . . . with the taxpayer paying 122 for each passenger making a return journey to Dublin from the two airports.

The Kerry-Dublin and Galway-Dublin routes have the lowest level of subvention, with subsidies of 64.68 and 76.94 respectively for a return flight.

The government awarded new contracts to operate the six public service obligation (PSO) regional air routes last summer.

Aer Arann was awarded the contracts on routes linking Dublin to the regional airports in Galway, Kerry, Sligo and Donegal, while Scottish regional carrier Loganair was given the contract on the Derry-Dublin and Knock-Dublin routes.

The subvention from the state for the PSO routes is 45.8m for the three-year period of the contracts.

Aer Arann chief executive Padraig O Ceidigh told the Sunday Tribune last year that the PSO model was used in every EU country and that the Irish subvention per passenger was the third or fourth lowest in Europe.