A guarantee to prevent passenger charges rising on the back of an expanded Heathrow has been demanded by Virgin Atlantic as the airport starts consultation on its third runway plans.

The call came as it emerged that the length of the proposed third runway could be shortened by 300 metres.

The 9% reduction from 3,500 metres could lessen the impact on residents of construction and cut noise over neighbouring homes by altering the path of aircraft taking off and landing.

However, the runway will still need to cross the M25 motorway.

Heathrow today confirmed that feedback is being sought through one of the UK’s largest-ever public consultations on potential infrastructure options including:

• Three shortlisted options for a new north-west runway with length varying from between 3,200 and 3,500 metres

• Potential locations to expand terminal infrastructure: east of Terminal 2, west of Terminal 5 or a new satellite terminal by the new runway

• Proposed alignment of the M25: repositioning it approximately 150 metres to the west, and lowering it by seven metres in a tunnel and raising the runway height so it passes over the M25

• Options for changes to local roads and possible changes to two junctions leading to the M25

Heathrow recently slashed £2.5 billion of its projected costs by claiming it would build a smaller new terminal over existing transport and baggage infrastructure rather than a larger one which would need connecting to the airport’s services.

The airport is also asking for the public to review its plans to manage the effects of expansion on local communities and the environment. It has pledged to introduce a 6.5 hour ban on scheduled night flights.

Heathrow is seeking views on options for completing the expansion project over ten weeks until March 28 at 40 consultation events.

The airport’s revised proposals will then be subject to a second public consultation next year.

Parliament is expected to vote on a National Policy Statement in the first half of this year, which will set out the policy framework for Heathrow’s final planning submission.

Virgin Atlantic chief executive Craig Kreeger suggested there should be a “passenger cost guarantee” to ensure airport charges do not rise significantly from their current levels.

“Our passengers already pay the highest airport charges in the world – they should not be asked to pay even more to fund expansion,” he told the Daily Telegraph.

“To protect passengers, we’re calling upon Heathrow to introduce a passenger cost guarantee, setting out the total budget for delivering the expansion programme, committing that passenger charges will not increase in real terms, and guaranteeing to cover the costs of any overspend.”

His comments echo Willie Walsh, chief executive of British Airways owner International Airlines Group, who has urged Heathrow not to raise fees.

Tim Alderslade, chief executive of Airlines UK, the association that represents UK-registered carriers, said: “Airlines have been consistent in their support for expansion at Heathrow and will be making the case for a new runway before the expected parliamentary vote in the summer.

“However, they have also been clear that this backing remains conditional upon costs being kept under control and passenger charges not increasing in real terms, and they will reserve the right to withdraw their support if this is not achievable.

“The government has rightly set out that lower fares are one of the key drivers of expansion at Heathrow, but if charges have to increase to pay for a disproportionately expensive runway, the resulting cost pressures will force up passenger fares and put at risk the viability of new and existing routes, which post-Brexit would see the UK fall further behind our international rivals in Europe and the Middle East with respect to international connectivity.

“We look forward to seeing further detail from Heathrow as to what we are our customers will be asked to pay for, and are committed to continuing to work with the airport and the Civil Aviation Authority to bring down the cost of the scheme further so that charges do not increase.

“This is the only way that a new runway can be successfully built that will deliver greater connectivity and economic activity for all parts of the UK.”

Heathrow executive director expansion, Emma Gilthorpe, said: “When the government announced its support for Heathrow expansion it made a clear commitment to keeping Britain open for business.

“We want an expanded Heathrow to be the world’s best airport, ensuring that our country and its future generations have the infrastructure they need to thrive.

“We need feedback to help deliver this opportunity responsibly and to create a long-term legacy both at a local and national level.

“Heathrow is consulting to ensure that we deliver benefits for our passengers, businesses across the country but also, importantly, for those neighbours closest to us.”

A spokesman for alternative extended runway concept, Heathrow Hub, said: “It is unbelievable that nearly six years into this process, Heathrow are still producing new ideas.

“This time, the airport claims it wants to move the M25 150 metres to the west, dig the motorway into the ground, cut the runway length and put it on a ramp.

“But there is precious little detail on how this will be done in practice, or what the implications will be of closing or restricting the M25.

“There are no detailed breakdown of costs and how these will be passed on to passengers and airlines. It is a Heath Robinson Plan.

“Both Chris Grayling, the transport secretary and Theresa May, the prime minister, are yet again being taken for fools by a major infrastructure provider.

“They need to demand proper detail from Heathrow and ensure the Department for Transport understand it, rather than letting Heathrow get away with issuing yet more pictures.”