Gatwick Airport runway expansion plans explained as Transport Secretary Heidi Alexander to announce decision in hours - what is at stake?

Transport Secretary Heidi Alexander will announce today (Thursday 27 February) whether Gatwick's expansion plan can go ahead. She has a deadline of the end of the day to decide whether to approve a development consent order application by the West Sussex airport to bring its emergency runway into routine use.

This would enable it to be used for around 100,000 more flights a year. In addition to making a decision on Gatwick, Ms Alexander also has a deadline of April 3 to determine whether Luton Airport's expansion plan can go ahead.

Meanwhile, Heathrow Airport is developing detailed plans for its third runway project. Gatwick's £2.2 billion privately financed project would see it move the emergency runway 12 metres north, enabling it to be used for departures of narrow-bodied planes such as Airbus A320s and Boeing 737s.

The plan also involves remodelling and replacing existing taxiways - which connect runways to terminals, hangars and other facilities - extending both terminals, and installing new aircraft gates. The airport says its scheme is "shovel ready" and construction could start this year.

It hopes the upgraded runway will be operational by the end of the decade. Gatwick chief executive Stewart Wingate said: "We can be a major part of the Government's drive for growth.

"We are already contributing over £5.5 billion to the UK economy and supporting over 76,000 jobs, but unless we can access greater airport capacity the UK will miss out on opportunities to enhance global connectivity and unlock further opportunities for trade, tourism and job creation." Gatwick says its plans would create £1 billion per year in economic benefits, and generate an additional 14,000 jobs.

However, local campaigners are opposed to Gatwick's expansion as they have expressed concerns over the impact on surface transport, noise, housing provision and wastewater treatment. Gatwick Area Conservation Campaign (GACC) is also calling for a halt on all airport expansion plans, citing the “shocking realities of climate change”, saying: “Expanding airports will result in an increase in emissions, worsening global heating even further.”

Airlines are behind it because if full permission is given, they – and therefore, passengers – won’t foot the bill. This sets it apart from Heathrow’s expansion plans, where a lot of the cost will be passed on. The Civil Aviation Authority says: "Capacity improvements at Gatwick are important to passengers and there are benefits to consumers in expanding capacity. This includes meeting the demands of passengers in the choice of destinations available, providing the opportunity for greater competition between airlines, and improving the resilience of airport infrastructure.”