Campaigners in Ealing hope controversial plans for a third runway at Heathrow could be grounded after a decision was pushed back by a month.
And protests at Stansted this week by antiexpansion group Plane Stupid led to calls for further action to disrupt flights in and out of Heathrow before MPs vote on the airport's future.
Transport secretary Geoff Hoon announced last week that a decision on whether to allow a third runway will be delayed until the end of January.
The move led to speculation that the plans could ultimately be shelved, but business leaders in the area who support a third runway are urging the Government not to waver.
Nic Ferriday, of Ealing Friends of the Earth, said the delay was "a sign of hope" that the Government is in retreat.
He said: "Our view is that it's because there's a split in the Labour party. It realises that this could cost it an electoral term. My guess is that they might put a third runway on hold for the time being, sensing the mood is not great at the moment."
But he said the alternative of 'mixed mode' - where both runways are used simultaneously for take-offs and landings - was even less desirable as it would cause greater disruption to more people.
Mr Ferriday said he supported the "effective" protest at Stansted which led to dozens of flights being cancelled, and believed similar things could be planned for Heathrow.
"We need things like this to raise the issue, just as we need other protests and marches," he said.
John Stewart, chair of the campaign group HACAN, said: "It does appear that the Government is having a re-think. It is under pressure not just from a wide range of opposition groups but also from the other political parties who have said they would scrap any expansion plans.
"And in recent weeks there have been signs of Labour MPs urging the Government to think again. The recession must be a factor too. The market may just not be there for expansion."
The delay has caused frustration among business leaders who see a third runway as vital to the prosperity of Ealing and its neighbouring boroughs.
Frank Wingate, chief executive of West London Business, the regional chamber of commerce, said: "We appreciate that the Government needs to give careful consideration to the Heathrow expansion decision, but construction of the third runway is the only logical conclusion.
"As we enter a recession, protecting the economic health of west London has never been more important for London and the wider UK economy.
"Delaying the Heathrow expansion decision is frustrating for our members. Not expanding the capacity of the UK's principal airport poses a serious threat of Heathrow declining, putting jobs and prosperity in west London at risk."
