The transatlantic airline industry needs to accept reform one step at a time, a top US aviation negotiator has told BBC News.
The US is gazing at distant horizons in airline trade talks
John Byerly, US Deputy Assistant Secretary for Transportation, said he needed to address political concerns over airline markets in Washington.
Speaking after last week's tentative deal on transatlantic routes, Mr Byerly said progress would come "in steps".
He denied the latest "open skies" deal favoured US carriers over EU airlines.
The EU and US reached a framework for a new agreement on Friday.
But a key EU demand that the US lifts a 25% limit on overseas ownership of its airlines was rejected during talks.
Mr Byerly admitted that the US stance on ownership was "the toughest issue" in talks over the international airline business and would entail controversial legislation in Washington.
"Europe has to work on us to build a consensus over transnational airline mergers," he said.
Condemning the existing 30-year-old Bermuda Two regulatory regime as "an abomination", Mr Byerly said any progress was to be welcomed and described the deal on the table as "focused on passenger benefits".
Mr Byerly said the agreement would "send a signal to the rest of the world that it is time to liberalise".
He said that if the EU ratifies the deal at a transport ministers meeting scheduled for 22 March this would encourage progress in other trade talks such as the stalled Doha round.
The EU believes the new deal could boost annual transatlantic passenger numbers by 50% over five years.
Asked how this growth could be squared with environmental concerns over airline activity Mr Byerly pointed out that the US and EU have "a commitment to co-operate over the environment, we take emissions very seriously".
Transnational airline moves do not appeal to US legislators
However, his position over environmental matters highlighted another transatlantic rift.
The US does not believe that carbon dioxide emissions can be tackled by the higher taxes on flights favoured by many European legislators.
"We need to improve air traffic management," said Mr Byerly, isolating flight time wasted in holding patterns before landing as an area that calls out for improvement.
British Airways and Virgin Atlantic have attacked the proposed deal, which would require them to face more competition on prized routes to and from Heathrow.
Mr Byerly issued a flat dismissal of their objections as motivated by self-interest and "their duty to their shareholders". The US thinks increasing access to these routes will benefit passengers.
"They're picking the pockets of consumers," was Mr Byerly's judgement on the UK incumbents with transatlantic slots.