Government backs £33bn plan for third runway at Heathrow

The government has today backed a £33bn proposal to add a third runway at Heathrow Airport, delivering another step forward for controversial plans that could almost double the airport's capacity.

In a statement issued this morning, Transport Secretary Heidi Alexander confirmed the government's intention to press ahead with the proposal, arguing it would deliver expansion that would align with legal obligations on air quality, environmental protection, noise, and climate change.

The plans from Heathrow Airport Ltd would see a runway of up to 3,500 metres in length added to airport, increasing its capacity to 756,000 flights and 150 million passengers a year by altering a stretch of the M25 motorway.

The plans also include a new terminal, dubbed 'T5X', the expansion of Terminal 2, and three new satellite terminals.

The proposal is still subject to planning processes, including consultation and parliamentary scrutiny. It is also likely to face intense opposition and legal challenges from environmental groups, which have long argued such an ambitious project would put binding climate and air quality targets at risk.

But Alexander insisted the project was in the UK's economic interests and could harness emerging clean technologies to ensure environmental obligations are not breached.  

"This decision marks an important milestone, one that reaffirms the UK's commitment to maintaining its position as a world leader in aviation, innovation and economic growth," she said. "Heathrow is our only hub airport, which supports trade, tourism and hundreds of thousands of jobs, and underpins prosperity across both the Southeast and regions of the United Kingdom.

"If Britain is to remain competitive in the decades ahead, we must ensure that our airport capacity matches our ambition as a modern, outward-looking and confident nation."

Heathrow Airport Ltd said the privately funded proposal would cost a total of £33bn at no cost to the taxpayer, including £21bn for the runway - inclusive of £1.5bn for M25 works - and £12bn for associated terminal infrastructure. The airport has also pledged £15bn in funding to modernise and upgrade existing infrastructure independent of the proposed third runway.

"We welcome the government's support for our scheme to build a third runway at Heathrow - the UK's gateway to growth," a Heathrow spokesperson said. "Expanding Heathrow will mean more connectivity, increased trade, improved passenger experience and a huge economic boost for the British businesses that will help design and build it."

According to the Financial Times, a proposal by hotelier Surinder Arora for a 400 metre shorter runway that would have cost less and avoided moving the M25 was rejected following a comparative assessment.

In today's statement, Alexander claimed Heathrow Airport Ltd's Northwest runway scheme offered the "most credible and deliverable option" - citing the "stronger comfort" it provides in relation to "efficient, resilient and sustainable operations" over the long-term.

Moreover, Alexander added that while the selected scheme requires more land, it would demand the acquisition of fewer residential properties and is considered a better fit for "next-generation aircraft".

Proposals for a third runway at Heathrow have been touted for decades but repeatedly stalled in the face of political opposition and concerns the project would struggle to comply with environmental and noise pollution rules, as well as the UK's legally binding climate targets.

In July the Prime Minister Keir Starmer suggested he would do "whatever it takes" to ensure "spades are in the ground" by 2030 to build a third runway at Heathrow.

Yet last month MPs warned the government's airport expansion drive risks putting the UK's ability to achieve its net zero targets in "serious jeopardy", unless its current approach to mitigating the climate impacts of aviation are strengthened and further safeguards are introduced to ensure expanded airport capacity does not lead to a breach of emissions goals.

Green groups today reiterated their scepticism at the government's claims that new low carbon fuels and zero emission aircraft can make airport expansion compatible with climate goals. 

Tony Bosworth, climate campaigner at Friends of the Earth, said the government-backed plan was "virtually the equivalent of bolting an airport the size of Gatwick onto Heathrow", arguing it would inevitably mean "more noise and air pollution for local communities".

"The government has said that airport expansion can only go ahead if it meets tests on climate, noise and air pollution, and growth," he said. "Proving that will be an immense task -  and breaking this promise will threaten their environmental integrity going into the next election. To avoid this, we need evidence-based decision-making, not a reckless gamble with our future."

Greenpeace's policy director, Dr Douglas Parr, argued approving a new, multi-billion-pound runway while hoping to meet environmental goals as "pure wishful thinking".

"The government is betting on unproven technology like sustainable aviation fuel to reduce future emissions, but you wouldn't sign a contract on a house before saving for a deposit," he added. "It's particularly hypocritical for this announcement to come just days after ministers, including from the UK, talked about phasing out fossil fuels at COP30.

"Instead of expanding airports, the Chancellor could reduce demand for flights and raise much-needed cash by taxing the small proportion of the population who fly frequently more heavily."

Alexander today moved to try and address concerns over the project's climate impact, confirming the government would publish a Stakeholder Engagement Approach to inform the development and review of the Airports National Policy Statement, which would include input from the UK's official climate advisors. "I am confirming that I have today written to the Climate Change Committee setting out how I intend to engage with them, so that their views can be fully considered as this process progresses," she said.

The department has also launched a consultation on a package of changes to help streamline airspace design, which is expected to help curb emissions from flights. "Alongside this, we continue to make progress on work to decarbonise aviation, including increasing the uptake of sustainable aviation fuel, and innovation in aviation technology," Alexander added.

The government is said to want Heathrow's third runway to secure planning permission by 2029 with flights then operating by 2035, meaning work must begin on a planning application before the Airports National Policy Statement is finalised by the end of 2026. However, Heathrow's spokesperson said further clarity on how the next phase of the project will be regulated was still required.

"We need definitive decisions from the Civil Aviation Authority (CAA) and government by mid-December so that delay to the project can be avoided and we can get on with delivering this vital project for our customers and for the UK," they explained.

Alexander's statement stressed the CAA will shortly set out further details on the government's approach to early cost recovery for developers and is today publishing a paper setting out potential future regulatory options for an expanded Heathrow.

Today's update comes despite Heathrow's largest customer, British Airways and Virgin Atlantic previously warning against building across the M25 motorway given its potential to increase costs for carriers and passengers.

International Airlines Group suggested the fee paid per passenger to the airport could double under proposals that involved crossing the M25, while industry body IATA warned under the current regulatory frameworks the selected proposal would be "unaffordable in both the short and the long term".

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