London Heathrow Airport has approved new investment to begin work on a planning application for a third runway, marking a major step forward for one of the UK’s most closely watched infrastructure projects.

The move signals renewed momentum behind Heathrow expansion, which backers say could unlock billions of pounds in private investment, strengthen airline networks, boost competition and reinforce the UK’s global trading links. The government is aiming to secure planning permission by 2029, with the first flights from a third runway expected within the following decade.

Heathrow said its shareholders strongly support the expansion, but stressed that the project will only proceed once the necessary regulatory and policy frameworks are firmly in place. Several key decisions due in 2026 are expected to determine how quickly the project can advance.

A series of regulatory milestones are scheduled over the coming months. In spring, the Civil Aviation Authority is expected to clarify how early project costs can be recovered. Over the summer, the Department for Transport will publish a draft Airports National Policy Statement, setting out the government’s updated approach to airport expansion. The CAA will also decide on the long-term regulatory model for Heathrow, a move that will be critical in shaping investor confidence.

Parliament is expected to review the final version of the Airports National Policy Statement in the autumn, establishing the planning framework that would underpin the third runway application.

Heathrow chief executive Thomas Woldbye said the board’s decision marked a significant step forward. He said the airport was now on track to seek planning permission by 2029 and described the move as a reflection of renewed ministerial commitment to expansion and progress in speeding up delivery.

“Heathrow expansion is a critical national project and a central part of our journey to make Heathrow an extraordinary airport, fit for the future,” Woldbye said, adding that maintaining momentum would require regulators and ministers to meet key milestones next year.

The third runway has long been framed as a strategic asset for the UK economy, with supporters arguing it would increase capacity at the country’s main aviation hub and help maintain London’s position as a leading global aviation centre. Critics, however, continue to raise concerns around environmental impact, noise and carbon emissions, issues that are expected to feature prominently as the planning process moves forward.