Heathrow's hopes for a third runway could be over after David Cameron left the decision to the new prime minister.
Theresa May and Michael Gove are now the front-runners to replace Mr Cameron but both serve areas close to the west London airport and their constituents are unlikely to want its expansion.
David Cameron was expected to confirm whether projects at Heathrow or Gatwick would get the go-ahead in the coming weeks if the UK voted to remain in the EU.
But Mr Cameron's resignation following the Brexit vote means the decision will not be made until the autumn.
In trouble? Plans for a third runway at Heathrow could be threatened after the decision over expansion was delayed again.
Opposed: Tory leadership frontrunners Theresa May and Michael Gove both have constituencies near Heathrow and will come under pressure not to back a third runway
Transport Secretary Patrick McLoughlin told the House of Commons: ' I had hoped that we would be able to announce a decision on airport capacity this summer.
'Clearly any announcement on airport capacity would have to be made when the House is in session and being realistic, given recent events, I cannot now foresee an announcement until at least October.'
In July last year the Davies Commission called for airport expansion by 2030 and recommended the building of a third runway at Heathrow.
But in December the Department for Transport announced that further investigation into noise, pollution and compensation would be carried out before a decision is made.
Mr McLoughlin went on: 'We aim to publish the further analysis on air quality soon.