European and US negotiators have reached agreement on a so-called open skies deal, which will allow an increase in air travel between the EU and the US.
The deal is crucial for Aer Lingus, which is planning a big expansion in its highly profitable American routes.
However, it also spells the formal end of the mandatory Shannon stopover. The mandatory stopover is being phased out through a transitional arrangement and will come to an end next April.
The European Commission has called the deal the biggest shakeup in international aviation since the Chicago Convention of 1944.
It will sweep away many of the restrictions that have held back or disadvantaged European airlines - especially provisions that should see any European airline being free to fly to any city in the US from any city in the EU.
Under the Chicago Convention an Irish airline can only fly to the US from Ireland, and because of the restrictive nature of the Shannon stopover, Aer Lingus has only been allowed to fly to a small number of US destinations.
This deal should clear the way for Aer Lingus to open up a range of new routes. The company is due to take delivery of two large new Airbus planes, bought for the north Atlantic run, in the next two weeks.
However, the deal opens up the prospect of more US competition on the Dublin-Washington and Dublin-Chicago run.
And a consequence of the new freedom for airlines to operate is the ending of the Shannon stopover. Under the agreement the stopover will be phased out over a short period.
The deal is still subject of the agreement of EU transport ministers meeting in three weeks time. If they give the nod, it will be signed at an EU-US summit in April.
According to the Commission the open skies deal will affect some 60% of world airline traffic. It claims it will add some €12bn annually to the aviation business.
