Heathrow Hub says there have been two “significant changes” in the circumstances around Heathrow’s expansion plans since the government gave expansion at Heathrow the green light in June 2018.

The first, says Heathrow Hub, is the “spiralling cost” of the airport’s scheme, while the second is what the group describes as the “incompatibility” of the third runway plan with the government’s pledge to achieve net-zero carbon emissions by 2050.

It has called directly on prime minister Boris Johnson and transport secretary Grant Shapps to intervene.

Heathrow currently plans to grow capacity by nearly half via the construction of a third runway north-west of the airport, subject to gaining necessary planning and development approvals.

Heathrow Hub, by contrast, proposes achieving the same increase in capacity by extending Heathrow’s existing northern runway to create two in-line runways allowing aircraft to land on one and take off from the other simultaneously. It says its proposal would be “cheaper, greener, quicker, simpler and quieter” than Heathrow’s government-backed plans.

The group says Heathrow’s third runway plans “continue to veer from the designated Airports National Policy Statement (ANPS)”, which it sought to quash in the High Court last year. A Court of Appeal decision is pending.

These include: increasing costs; an overt reliance on a significant increase in flights, around 260,000 annually, to make the scheme viable; and a reluctance to approach the objective to expand Heathrow in a transparent manner.

Jock Lowe, Heathrow Hub director, accused the airport of attempting to block disclosure of its surface access plans and making changes to the scheme contrary to the ANPS.

“The complexity of the project and its associated costs continue to balloon, affecting airlines, consumers and local communities who will suffer as a result of increased costs, noise and emissions,” said Lowe.

“The government should stop prevaricating and review this unnecessarily expensive and disruptive option for Heathrow expansion.

“Our extended runway can still, even now, be built before the third runway. It’s a solution deemed viable by the Airports Commission and it will cost just £4.7 billion for the first phase. It does not rely on extra flights, it will make the airport more efficient, and it will ensure passenger charges stay flat.

“And it is a way out for Boris Johnson, who rightly does not like the third runway.”

TTG has approached Heathrow for comment.