The government has chosen Heathrow’s £49 billion expansion plan as the basis for building a controversial third runway, bringing the project another step closer to reality – but MPs are expected to approve it next year before details emerge of exactly where hundreds of thousands of extra flights will fly over the South East.
Transport Secretary Heidi Alexander announced on Monday that Heathrow Airport Limited’s proposal for a 3,500-metre northwest runway has been selected over a cheaper alternative from hotel tycoon Surinder Arora. The decision marks the most significant progress on the long-stalled project since the Airports National Policy Statement was first approved in 2018.
For Putney residents, the expansion threatens major changes to aircraft noise patterns. The third runway would end the current alternation system that gives communities a half-day break from overhead flights.
Communities across Balham, Battersea, Clapham Common, Putney, Tooting, and Wandsworth Town face increased noise pollution due to the loss of runway alternation, with aircraft overhead for more hours each day when westerly operations are in place, with no respite after 3pm, according to Wandsworth Council’s most recent statement on the issue.
The approved plan
The project could increase flight movements by 57 percent and passenger traffic by 79 percent by 2035, bringing Heathrow’s capacity to 756,000 flights and 150 million passengers annually – up from 83.9 million last year.
The £49 billion total cost breaks down as £21 billion for the runway itself (including £1.5 billion to divert the M25 motorway through a tunnel), £12 billion for new terminal infrastructure including a T5X terminal complex, and £15 billion to upgrade existing facilities.
The project would involve building the 3.5km runway over the M25, adding massive cost and disruption. Heathrow says the M25 rerouting would take place on land 130 metres west of the existing motorway with the switch made “in a series of carefully planned overnight operations”.
Heathrow insists the expansion will be 100% privately financed, though costs will be passed to airlines through higher landing fees and ultimately to passengers through ticket prices.
The flawed approval process
The critical issue is the timing of the parliamentary vote. The government plans to consult on amendments to the Airports National Policy Statement by summer 2026, with parliamentary scrutiny next year and a planning decision hoped for by 2029. MPs will be asked to approve the policy framework before specific flight path details are published, meaning they’ll vote on expansion without knowing which communities will bear the noise burden of hundreds of thousands of extra flights.
London’s airspace will be redrawn to ensure the capital’s skies are ready for more departures from a third runway from 2035, but these detailed flight path plans won’t be available when MPs vote on the expansion principle.
Wandsworth Council issued a strongly worded statement in January opposing the expansion. Council Leader Simon Hogg said: “We cannot stand by and let Heathrow have a green light to enact such unwelcome changes on our communities. The third runway not only threatens our environment but will also severely affect the day-to-day lives of thousands of Wandsworth residents. This fight is about protecting their quality of life, holding the Government accountable for its climate promises, and ensuring a sustainable future for our borough”.
Putney MP Fleur Anderson, who previously stated in 2020 that “the expansion of Heathrow is fundamentally at odds with tackling climate change,” has been notably quiet since the Labour government revived expansion plans in January, as we reported in March. She has not issued a statement on this week’s decision. As a government MP, her silence contrasts with her previous environmental campaigning.
What happens next
The selection of Heathrow’s scheme doesn’t represent final approval. Any amendments to the ANPS will be subject to consultation next summer after the Transport Secretary committed to completing the process 3 years faster than production of the policy statement in 2018.
Following consultation and parliamentary approval of the revised ANPS, Heathrow would then submit a Development Consent Order application, with a planning decision possible by 2029. If approved, construction would take six years, with the runway operational by 2035.
The government insists expansion must meet four tests: climate change obligations, noise mitigation, air quality standards, and economic growth. The government has been clear expansion plans must meet the UK’s legally binding climate obligations alongside balancing delivering economic growth as well as air quality and noise obligations.
However, the fundamental problem remains: residents won’t know if they’ll be living under hundreds of thousands of extra flight paths until after the principle of expansion has been approved by Parliament.
