Scottish Conservative leader Ruth Davidson has added her voice to those in favour of a third runway at Heathrow, arguing the move is in Scotland's economic interests.
Ms Davidson's U-turn follows a senior Tory's challenge to Prime Minister David Cameron last week to reverse the coalition government's policy to stick to two runways.
Writing in today's Scotland on Sunday, Ms Davidson said: "As a Westminster candidate in the 2010 election, I campaigned on a manifesto containing opposition to a third runway, but priorities - and economic landscapes - change."
Ms Davison said a two-runway Heathrow would lead to a reduction in connections between Scotland and London, and force long-haul passengers to travel to other airports in Europe such as Amsterdam's Schiphol for flights to the rest of the world.
She wrote: "In politics, you need to be big enough to change your mind and I believe there is now an overwhelming argument for a third runway.
"However, for business in Scotland to enjoy the full benefits of this extra capacity, air passenger duty must also be scrapped."
Ms Davidson said taxes on air travel were now higher in the UK than anywhere else in the world.
Chairman of the UK Government's Energy and Climate Change Committee Tim Yeo urged a U-turn on Heathrow policy last week, insisting that expansion of Heathrow would give the Government "a sense of mission".
Downing Street said the coalition will stick to its commitment of having no third runway.