Heathrow Defends £49 Billion Third Runway, Claims It’s Still on Track for Net Zero by 2050

Image Credit: Heathrow Airport

Heathrow has officially resubmitted its long-anticipated proposal for a third runway, describing it as "shovel-ready" and part of a wider £50 billion investment package. According to the UK government, expanding what is already Europe’s largest airport could lead to the creation of 100,000 jobs and unlock new growth opportunities for the country.

The planned runway would stretch two miles, or 3.2 kilometres, and cross over a rerouted section of the M25 motorway. If completed, the expansion would enable more than 750 additional flights every day to and from London. In terms of passenger volume, Heathrow believes the new infrastructure could help raise its annual capacity to a staggering 150 million people.

But not everyone is on board. Environmental groups have labelled the expansion a doomed and short-sighted venture. They argue that it will release millions of tonnes of carbon dioxide while primarily catering to affluent, frequent flyers. Despite this criticism, Heathrow maintains that with the right level of government backing, it could secure planning permission by 2029 and open the new runway to traffic by 2035.

Interestingly, the blueprint remains essentially unchanged from the version submitted in 2019. That earlier proposal received in-principle approval from both the government and Members of Parliament, only to be briefly blocked on climate grounds after legal challenges by environmental campaigners. The block was later overturned on appeal in 2020.

Still, the project was shelved during the pandemic as global travel demand collapsed. Since then, Heathrow’s shareholder group, which includes the French investment firm Ardian as well as the sovereign wealth funds of Saudi Arabia and Qatar, has been calling for greater legislative clarity and longer-term political alignment before moving forward with a complete planning submission.

Chancellor Rachel Reeves has voiced her strong support for the expansion, yet Heathrow is seeking more than just verbal endorsement. The airport is seeking firm policy commitments to guard against the kind of political reversals that derailed past runway plans. These include the modernisation of UK airspace to accommodate new flight paths, along with the passage of the Planning and Infrastructure Bill.

Heathrow is also requesting assurances from the Civil Aviation Authority. Specifically, it wants the regulator to approve pricing arrangements that would let the airport charge airlines enough to recover the enormous cost of building the new runway.

Speaking of costs, the project's financial scale has grown significantly. The estimated price tag for the runway alone now sits at £21 billion, a sharp increase from the £14 billion estimate six years ago. This is attributed mainly to soaring construction and material costs. Additionally, a £12 billion extension to Terminal 5 is planned to accommodate the surge in passenger traffic. An additional £15 billion will be spent on broader airport upgrades, regardless of whether the runway ultimately proceeds.

The government has promised to evaluate Heathrow’s revised plans over the summer, with a potential decision expected by September. It will also consider a rival proposal from the Arora Group. This private developer has proposed building a shorter runway to the east of the existing terminals.

A Heathrow spokesperson acknowledged that the airport is open to conversations with airlines about alternative layouts, including the possibility of a shorter runway. However, the company remains convinced that no competing proposal can match the long-term value and benefits of its current plan.

The push for expansion has drawn strong backing from business groups, trade unions and several branches of government. Supporters argue that an upgraded Heathrow is vital for the UK’s competitiveness in global aviation and trade. However, critics continue to raise serious concerns, highlighting the contradiction between unchecked airport growth and the country’s stated goal of achieving net-zero emissions.

Even among those watching from the sidelines, there is a lingering sense of scepticism. Many wonder whether this project will finally break ground or whether it will join the list of ambitious infrastructure plans that have failed to take off, despite having passed through the hands of not one, but two different governments.