Up to £500 million could be spent by Gatwick to move its emergency runway by 12 metres, bringing it into full passenger use.

The UK’s second busiest airport unveiled a masterplan this morning detailing a number of different growth scenarios.

These include creating a fully operational second runway that will allow it to handle up to 50,000 extra flights a year.

The plan involves moving an existing standby runway — only used in emergencies when the main runway is closed — slightly to the north to make sure that it complies with international safety regulations.

New taxiways to and from the runways and additional stands will also be created.

The new strip will be used only for take-off by short-haul aircraft, with all landings taking place on the main parallel runway.

A 40-year agreement signed with West Sussex county council promising not to use the standby runway for regular flights expires next year.

Gatwick chief executive Stewart Wingate told The Times that the airport would spend between £400 million and £500 million on the revamp.

The airport wants to bring the new runway into operation by the summer of 2025. A planning application would be lodged in early 2020.

This would allow Gatwick to expand into a two-runway hub only six months before the expected completion of a third runway at Heathrow.

Gatwick will consider restrictions or a ban on night flights as part of a deal to secure access to the additional runway.

The airport confirmed this morning: “Under its current planning agreement, Gatwick’s existing standby runway is only used when the main runway is closed for maintenance or emergencies.

“However, the 40-year planning agreement will come to an end in 2019.

“The draft master plan sets out for the first time how Gatwick could potentially bring its existing standby runway into routine use for departing flights, alongside its main runway, by the mid-2020s.

“This innovative development, which would meet all international safety requirements, would be delivered without increasing the airport’s noise footprint and provide greater operational resilience.

“While in the early stages of exploration, Gatwick is confident the project would remain within the existing airport footprint and existing framework for airport charges.

“Should the airport decide to further progress the use of the existing standby runway, it would submit a detailed planning proposal and follow a Development Consent Order (DCO) process, which would include a full public consultation.”

A 12-week public consultation is launched today to gather feedback and views on the draft master plan.

All responses will be reviewed before a final version of the master plan is agreed early next year.

Wingate said: “Our draft master plan marks the start of a new phase for Gatwick – building on what has made the airport the success it is today, and pioneering again to take advantage of the exciting opportunities that lie ahead.

“As the UK heads towards an important new chapter, Gatwick’s growing global connections are needed more than ever but this must be achieved in the most sustainable way.

“From using new technologies on our main runway, to the innovative proposal to bring our existing standby runway into routine use, our draft master plan offers agile, productive and low-impact ways of unlocking much-needed new capacity and increased resilience from within our existing infrastructure.

“Gatwick’s growth has been built through partnership so as we look ahead at our future development, we want to shape these plans together with our local communities, our passengers, our airlines and partners. We would encourage as many people as possible to take part in our consultation process. This will help shape our plans for securing the region’s prosperity.”

But the move has been criticised by opponents of Gatwick, which handles 281,000 flights a year and 46 million passengers, as an attempt to expand “by stealth”.

Sally Pavey chair of Communities Against Gatwick Noise and Emissions, said: “This is despicable behaviour by Gatwick management and clearly shows their contempt for us communities of Sussex, Surrey and Kent.

“They obviously can’t be trusted as they have illustrated today that they do not care about communities that surround them in rural communities that are suffering today intolerable noise and fall out of Gatwick’s growth.”

The group pointed out that the emergency runway was never designed to be used for anything other than to deal with air incidents when things go wrong.

The Civil Aviation Authority has always been concerned about safety of using this emergency runway in conjunction with the main runway, CAGNE added.

Pavey added: “This announcement today is shameful, a second runway by the backdoor.”

However, the plan is likely to win government support after the publication of an aviation blueprint in June that pledged to allow all airports to make “best use of existing runways”.

Norwegian CEO Bjorn Kjos welcomed the expansion plan and said: “Our co-operation with Gatwick Airport has given us a strong platform to deliver more consumers lower fares on intercontinental flights.

“As we continue our global growth, we welcome any increases in airport capacity in the Greater London area that support our commercial interests and ultimately benefit consumers.”

Jason Geall, vice president and general manager Northern Europe at American Express Global Business Travel, said: “In order for UK businesses to grow and develop relationships, we need the right infrastructure in place to facilitate travel, but currently we’re hindered by a lack of runways.

“Until now, the spotlight has been on Heathrow’s potential third runway, but progress has been slow.

“The idea that Gatwick could open a second runway is a welcome prospect. It sends a signal to the world that the UK is open for business.”

CBI director general Carolyn Fairbairn said: “Now more than ever, unlocking new aviation capacity to deliver global trade links is critical for a strong UK economy.

“London’s airports are set to be full in the next decade, so the CBI welcomes Gatwick’s highly productive proposals to deliver increased capacity that complements expansion schemes at other airports.

“This will drive trade and investment, create new jobs and help British businesses thrive.”