The campaign led by midwest companies protesting at Aer Lingus's decision to end flights between Shannon and Heathrow is exaggerated, a report drawn up by senior civil servants has found.
It is among the conclusions of the cross-departmental team of officials set up to "bring a clear analysis and set out options" for the Government.
The Atlantic Connectivity Alliance campaign's charge that Shannon would lose one-stop links to 40 major destinations is wrong, according to the officials' report.
"Our research indicates that one-stop connectivity would be retained with 12 of these destinations, principally through US hubs served directly from Shannon. Furthermore, there is no record of any business travellers from Shannon seeking to link, through Heathrow, with a further 15 of the destinations listed in the last three years."
The numbers of all types of passengers travelling from Shannon for connecting flights from Heathrow had dropped by more than half in less than two years. Meanwhile, business class passenger numbers from Shannon using Heathrow for onward flights had also dropped by half.
However, the officials did accept that the loss of the Aer Lingus links will have "a negative effect" on the midwest's connections to Asia, and some European destinations.
However, the officials, led by Department of the Taoiseach assistant secretary Mary Doyle, cast doubt on local claims that the loss of the Aer Lingus links will cost future investment.
"It would not be valid to conclude that a location lacking immediately proximate direct access to a major European hub cannot attract investment," said the report.
Accepting that local businesses had "fully legitimate concerns", the officials said "the waging of any public campaign" often leads to the emergence of "an unbalanced picture".
"We would suggest that the impression conveyed by the [Atlantic Connectivity Alliance] list that the region is being cut off from the world is entirely disproportionate. We are concerned that nothing be done which may be used to advantage the competitors of the region."
Ten thousand American tourists who previously flew with Aer Lingus to and from Heathrow would not be affected by the change, because they could switch to a different British airport. However, the officials conceded that 10,000 more "high-yield" Americans "who backtrack to Ireland via Heathrow" will "now need to consider other options to get to Ireland".
A draft of a Shannon airport business plan is to be prepared this month and presented to the airport's board and the Dublin Airport Authority before possible presentation to the Government.
The loss of the Aer Lingus service would add 62 minutes to short-haul European flights, which the officials described "as an adverse effect" although "perhaps not as severe as might initially have been assumed".The officials conceded that the lack of evening flights from Dublin to Shannon would be a serious handicap, forcing executives to overnight in Dublin.