Heathrow Airport has delayed the planned opening of its third runway by four years to 2039, citing the time required to progress the project through planning.
The airport said it remains focused on securing planning permission by 2029 and expects the runway to open within a decade of approval.
£49bn expansion plan
Heathrow’s expansion proposal, submitted in August 2025, is designed to increase passenger capacity by 50% to as many as 150 million travellers a year. The scheme would also support up to 756,000 flights annually.
The plans include a 3,500m north-western runway, a new terminal known as T5X, three additional satellite terminals and upgrades to existing facilities. The longer-term proposals also include the closure of Terminal 3.
Heathrow has outlined £21bn of investment in the new runway and related airfield infrastructure, £12bn for terminal expansion and £15bn to modernise existing terminals.
A Heathrow spokesperson said: “Our focus has always been to secure planning permission by 2029. Once achieved, the runway will be open within a decade – and the benefits of expansion can be felt from today.”
The airport said the project would create at least 108,000 jobs and generate investment in supply chains across the UK. It described the scheme as a national project that would be 100% privately financed.
Planning framework and surface access
The government supports the expansion and committed last year to updating the Airports National Policy Statement around the Heathrow scheme. A revised planning framework was published in June 2026.
However, the Department for Transport said there is currently no live planning application for a third runway. A spokesperson said the timetable had always been ambitious and that ministers would continue working with Heathrow and other stakeholders to establish a framework under which an application could be considered.
Questions also remain over whether the local rail and wider transport network could accommodate the additional passengers. Keir Mather, parliamentary under-secretary at the Department for Transport, said an application would not necessarily have to be accompanied by a new rail infrastructure application.
Instead, a promoter would need to set out the rail improvements it intended to deliver and provide a “credible plan” for them as part of a wider surface access strategy for an expanded airport.
GMB London regional secretary Warren Kenny backed the project and said the delay should prompt ministers to remove planning barriers. “A project taking longer to build is not a reason not to build it. It’s a reason to start now,” he said.