London Heathrow’s third-runway plan will be based on the development proposal submitted by the airport’s operator, which favours a longer runway of 3,500m.

UK transport secretary Heidi Alexander says the scheme submitted by Heathrow Airport offers the “most credible and deliverable option”.

She says this is mainly due to its “relative maturity” along with confidence in the feasibility of surface-access plans.

The UK’s Department for Transport had been assessing the Heathrow Airport proposal as well as an alternative from Arora Group which put forward a plan involving a shorter 2,800m runway.

Arora Group had claimed its short-runway scheme would avoid interruption to the important orbital highway that circles London.

But Alexander says the Arora proposal will still have a “considerable impact” on the highway. She adds that, while Heathrow Airport’s plan needs more land, it involves fewer acquisitions of affected residential properties.

The longer runway is “advantageous”, she adds, because it offers “greater resilience and potential futureproofing”.

Heathrow Airport’s plan provides the “greatest likelihood” of meeting ambitions for a decision on development consent application within the current parliamentary session, she says.

But the government stresses that the Heathrow Airport scheme will simply “inform” a continuing review of the national policy statement on airports, which guides the government’s approach to securing airport capacity in the southeast UK.

“Selection of the scheme to inform the remainder of the review does not represent a final decision on a third runway scheme or design,” it states.

But it adds that the favouring of Heathrow Airport’s proposal means a third runway is a “step closer” to a 2029 planning decision and becoming operational in 2035.

The national policy statement review is intended to update the statement to account for any changes in legislation and aviation forecasts; amendments will be subject to consultation next year.

“Any scheme identified in an amended [national policy statement] will still need detailed consideration…in any development consent order sought under planning legislation,” says Alexander.

The government expects that Heathrow Airport will submit an application for development consent for its northwest runway proposal once the policy statement review is complete.

While the rival Arora Group acknowledges the government’s preference for a longer runway, and will support the decision, it points out that the option for a promoter “other than Heathrow Airport…remains possible”.

“We are now reviewing how our plans will be adjusted to the longer runway scheme with the intention that we commence our own development consent order,” says chair Surinder Arora, adding that a “clear and transparent process” for selecting a promoter is “imperative”.