Aer Lingus's controversial new route from Belfast International Airport to London Heathrow has opened today.
The company - which closed its Shannon to Heathrow route last year - will operate three daily return flights from the North's airport following a €100 million investment to establish its first regional hub outside of the Republic.
Six airlines are now offering eight routes between Belfast and London, but Aer Lingus chief executive Dermot Mannion said he is confident the company will meet business targets of 500,000 passengers by year end, despite the heavy competition.
"I remain very confident. We have already received 100,000 bookings so far so we're well on target," he said.
Heathrow is the fourth of nine routes the airline will operate out of Belfast.
As passengers queued to check-in for the Heathrow flight, Ryanair staff handed out vouchers for free travel on their service from Belfast City airport to London Stansted.
Dismissing the move as a stunt, Mr Mannion said Ryanair chief executive Michael O'Leary "knows full well no matter what stunts he pulls Aer Lingus is going to stay independent, and there is very little he can do about it".