The final Aer Lingus flight from Shannon to London Heathrow departs at 5.25 pm today ahead of the company's controversial move to its new Belfast hub.
Politicians and businessmen in the Shannon area have insisted the move would hit both business and tourism but the airline said it had made a commercial decision which would be proved right.
There are no plans for any official ceremony to mark the last flight to London.
The three times a day service, due to begin tomorrow, is to use landing slots at the main London airport which the airline controversially decided to switch to the Belfast route by scrapping long standing services from Shannon .
The chief executive of Shannon Airport Authority, Pat Shanahan, resigned in protest over being kept in the dark about the decision until it was announced by Aer Lingus last August.
CityJet, the Irish subsidiary of Air France, has stepped in to provide a new route from Shannon to Paris - starting next month - which will provide onward connections to well over 200 international destinations. However no one has yet come up with a replacement Heathrow service.
Aer Lingus says it expects to carry over 500,000 passengers to and from Belfast International on all its routes in the first year - pushing the airport's numbers through the six million mark for the first time.
The airline is in direct competition on most of its routes out of Belfast and chief executive Dermot Mannion said they were up for a fight.
"I think it is going to be very competitive out of Belfast and it is going to be a good proposition for the Northern Ireland customer," he said.
At Shannon , the last Aer Lingus flight to Heathrow took off today.
"It's the end of an era and a sad day for many people but we are firmly looking to the future now," said a spokesman for the Shannon Airport Authority.