Pilots union BALPA has accused the Government of making a u-turn over airport expansion.
General Secretary Brian Strutton said delaying the decision is bad news for the aviation industry and the UK economy.
"Pilots believe airport expansion is vital to the UK economy and we are disappointed about further delays to a decision," he said.
"After telling everyone we would finally know the outcome this week, the PM has now done a u-turn and built in more delay and prevarication.
"This is not good news for the UK aviation industry, which is already struggling with the uncertainties of Brexit."
The Institute of Economic Affairs said another delay was a ‘severe blow for our struggling aviation industry, business and consumers’.
Prime minister Theresa May was expected to make a final decision this week but has now said the final vote won’t take place until next year to give time for public consultation.
This gives Heathrow opposers, such as Boris Johnson, freedom to speak out against any expansion at the London airport.
Critics say the vote was delayed over fears that Tory MPs could resign their seats if ministers backed a third runway at Heathrow.
Conservative MP Zac Goldsmith has threatened to resign if Heathrow expansion was given the greenlight, which would trigger a byelection in Richmond Park. He is supported by MPs in neighbouring constituencies.
