Travellers will not return to the restrictions which existed before the new Open Skies deal came into force, Pierre-Henri Gourgeon, deputy ceo of Air France KLM, said.
Mr Gourgeon said he did not know whether the second stage of the deal between the US and the EU, partly concerning ownership of carriers in America, would come into being.
But he added: “What you can see is that the customer will enjoy a very different offer at Heathrow from a number of airlines including Air France, Delta, Northwest and Continental.
"This is something that the customer will want to keep for the future. I don't see a return to the former situation. It would not be accepted by the customer," he said.
Mr Gourgeon was speaking at a joint Air France Delta Air Lines press conference in London today (March 31) to mark the start of new transatlantic services from Heathrow by the two airlines.
The Open Skies deal which lifted restrictions on transatlantic flights from the London airport came into force over the weekend.
Under the first stage of the new deal, Air France launched a daily Heathrow-Los Angeles service while Delta started new routes to Atlanta and New York.
Continental Airlines also started new services between Heathrow and Newark and Houston while Northwest Airlines launched new routes to Minneapolis, Detroit and Seattle.
Talks on the second stage are due to begin in May but there are fears among European carriers and EU politicians that the US will not relax its tough rules on foreign ownership.
This could lead to the scrapping of the first phase agreement and a return to the situation where only four carriers were allowed to fly transatlantic services out of Heathrow.
At the press conference, Mr Glenn Hauenstein, executive vp and chief of network and revenue management for Delta, said he hoped the application for joint anti-trust immunity by four carriers,
Air France, Delta, KLM and Northwest would be approved by the US Department of Transportation "in the not too distant future."