The Heathrow third runway delay is now official: airport bosses have told the Government that the current 2035 opening deadline cannot be met, pushing the expected completion to 2039. The announcement lands as Labour’s annual conference gets under way in Liverpool, casting a shadow over plans to use the project as a driver of economic growth.
The 2035 target was set by then-chancellor Rachel Reeves, who announced government backing for the scheme in January 2025, according to the BBC. In a major speech on infrastructure, Reeves positioned the runway as central to growing the economy, saying it would create 100,000 jobs. The project carries an estimated price tag of £49 billion, according to GB News.
Why the Heathrow Third Runway Delay Has Happened
The airport has always maintained that securing planning permission by 2029 is the first essential step, with the runway then open within a decade of that. The four-year slip from 2035 to 2039 reflects that original sequencing more honestly than the target Reeves set.
Airport bosses believe the timetable could be tightened, but say that would require removing regulatory red tape beyond the planning law reforms the Government has already made. In other words, the 2039 date is the realistic baseline; getting back closer to 2035 would need further action from Whitehall.
A Heathrow spokesperson set out the airport’s position directly: ‘It’s right that ambitious targets were set; the sooner expansion begins, the sooner the whole UK will benefit. 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. At least 108,000 new jobs and billions invested in supply chains in every part of the country. This is a national project, 100% privately financed, which will support growth today and secure the UK’s position in the global economy once the runway opens.’
A Department for Transport spokesperson noted that there is currently no live planning application for a third runway, adding that the timeline had ‘always been ambitious’ and that the Government would continue working with Heathrow and other stakeholders to ensure the right framework is in place for a planning application to be considered.
What the Heathrow Third Runway Delay Means for Growth
The slip is a complication for those in government who had tied the project closely to growth ambitions. Andy Burnham had previously been critical of the scheme, though the BBC reported he described himself as ‘open-minded’ about it when he came to office. The delay does not kill the project, but it does lengthen the wait for the economic benefits its supporters have promised.
Climate obligations add a further layer of complexity. The Climate Change Committee, the expert panel that advises the Government on carbon targets, said earlier this month that Heathrow expansion cannot go ahead unless the aviation industry is required to cut its emissions. The committee also said that the cost of international flights might have to rise by hundreds of pounds by 2050 to fund measures that would help the airline sector reach net zero, meaning that its overall carbon output would be reduced to nothing overall.
Transport Secretary Heidi Alexander pushed back on the idea that expansion and climate commitments are incompatible. She told the Daily Telegraph that the Climate Change Committee had set out ‘one view’ but that there was ‘more than one pathway to meeting our climate change obligations’. Alexander added that the UK’s climate targets are ‘economy-wide targets’ and that emissions need to be considered ‘holistically’ across the whole economy, not sector by sector. She also argued that an expanded Heathrow could serve as ‘the country’s front door’ to tourists from China and India.
The next concrete milestone the airport is working towards remains planning permission by 2029. Until a formal application is submitted and approved, the 2039 opening date itself remains a projection rather than a fixed commitment.
