Demands from airlines to use an expanded Heathrow give the UK "strong cards in our hand" for Brexit negotiations, Transport Secretary Chris Grayling has said.
The minister expressed confidence that flights will not be grounded after the UK withdraws from the EU because "it's in the interests of everyone" to maintain the open market for aviation.
Ryanair boss Michael O'Leary has repeatedly warned that airlines will be forced to cancel post-Brexit services from March 2019 if no agreement is reached by September, because schedules are planned about six months in advance.
The single market for aviation, created in the 1990s, means there are no commercial restrictions for airlines flying within the EU.
Speaking at the annual dinner of trade body Airlines UK, Mr Grayling claimed the planned third runway at Heathrow will help the UK secure the continuation of flights.
He said: "The demands of airlines across Europe to access Heathrow means we have strong cards in our hand for the negotiations."
The pro-Brexit MP for Epsom and Ewell told the audience of airline leaders, including British Airways chief executive Alex Cruz, that he is "absolutely sure that we will have a good working relationship" with the EU.
He went on: "UK airlines and airports will continue to flourish.
"That confidence comes from knowing that it is in the interests of all European countries - and they know it's in their interests - that that happens.
"It's in the interests of everyone who travels between them that we have an open, liberal arrangement for aviation post-Brexit.
"I know that you want certainty and quickly. So does the Government, so does the rest of the EU."
He added that aviation is a "key objective for the Government and the negotiating team".
The Department for Transport is due to publish final proposals for a third runway at Heathrow in the first half of the year for a vote in Parliament.
If the scheme is approved, the airport will submit a planning application after consulting local communities on detailed proposals.
It hopes to begin construction in early 2021, with the runway completed by the end of 2025.