Labour will abandon its previous support for building a third runway at Heathrow airport.
The Labour leader Ed Miliband had opposed its construction when he was in Government, but failed to persuade Gordon Brown to drop the party's commitment to expand Britain's largest airport.
Maria Eagle, the shadow Transport Secretary, will confirm the move today in a speech to the Airport Operators Association, saying that "the local environmental impact means this is off the agenda".
Ms Eagle will challenge ministers to take the politics out of aviation by working on a cross-party consensus on the issue.
In another major policy shift, she will call for an alternative line for the proposed High Speed 2 (HS2) rail link between London and the Midlands.
The Government is supporting the previous administration's recommended route through the Chilterns – a proposal that has sparked widespread anger in the Home Counties.
Labour is now arguing that it should run from Central London via Heathrow and skirt the M40.
The Transport minister Theresa Villiers accused Labour of an "opportunistic and last-minute announcement" and of playing politics with HS2. She said: "The people who strongly support the project around the country will not thank them for this irresponsible attitude."