Heathrow passengers face soaring ticket prices to fund a third runway, a London MP warned in the Commons.
Twickenham MP Munira Wilson also accused the Government of lacking the evidence for its policy of airport expansion.
Chancellor Rachel Reeves has backed another runway at the west London airport.
The Department for Transport is now drawing up the criteria for whether a third runway meets the Government’s tests on climate change, air pollution, noise and economic growth.
At transport questions in the Commons, Ms Wilson stressed: “The environmental audit committee recently found in their report that the Government is proceeding without the necessary evidence base to sufficiently underpin its economic arguments for airport expansion.
“Now senior figures in the airline industry are warning about serious economic consequences of the unaffordable, eye watering costs that will be passed on to their passengers.
“So will the minister now admit that the maths for Heathrow expansion simply don’t add up?”
Aviation minister Keir Mather rejected the claims about Heathrow, with the Department for Transport set to publish the draft Airports National Policy Statement (ANPS) this summer, which will provide the framework for making key decisions on airport growth.
He said: “She asks about the point around the case for Heathrow expansion and collecting the data in reference to it, the ANPS review is going to do exactly that, reflecting changes in legislation, policy and analysis.”
“Since the current ANPS was designated in 2018 it will ensure that any proposed scheme for expansion at Heathrow will be consistent, both with air quality obligations, but also to ensure that it contributes to economic growth across the entirety of the United Kingdom.”
The Government is backing Heathrow’s £33 billion scheme to expand the airport which will increase capacity by more than 50% to 756,000 flights a year, and involve moving the M25 which could create years of disruption for motorists.
The overall bill rises to £49 billion with improvements to existing terminals.
British Airways had argued that a shorter runway should be built to avoid having to move the M25 which will add to the costs of the project.
Airlines fear they will have to bear the cost of a third runway which would mean higher ticket prices.
Ms Reeves has stressed that the far wider use of sustainable aviation fuel (SAF) would mean that airports could expand while not breaking the UK’s legally-binding commitments on climate change.
However, ministers have now admitted that the Government may miss its target for the take-up of SAF.
Net Zero Secretary Ed Miliband has stressed that a bigger Heathrow can only happen if it does not breach the Government’s climate change goals.
Ministers are also supporting a new second runway at Gatwick, as well as more capacity at Luton and City airports.
Earlier this week, Heathrow’s chief executive Thomas Woldbye warned that it risks losing its position as Europe’s busiest airport this year because of a lack of capacity.
He stressed that this situation demonstrated why its project to build a third runway is “critical”.
The Civil Aviation Authority is scheduled in the summer to decide on a long-term model for airport charges, which is a key factor in investment for a third runway at Heathrow.
Parliament will be asked to decide on the final ANPS in the autumn.
Some 84.5 million passengers passed through the west London airport’s four terminals last year, a 0.7% increase from 83.9 million in 2024.
Its growth trails other European rivals because its two runways are full.
Heathrow’s passenger numbers were only narrowly ahead of Istanbul last year, which had 84.4 million passengers (up 5.5%).
Paris Charles de Gaulle was ranked third with 72.0 million passengers (up 2.5%), followed by Amsterdam Schiphol with 68.8 million passengers (up 2.9%) and Madrid with 68.1 million passengers (up 3.0%).
In January, Heathrow recorded 6.5 million passengers, a 2.0% increase from the same month in 2025.
