An extra 25,000 flights a year could come through Heathrow before the third runway is built, in plans revealed by the airport as it launched a fresh consultation over its airspace and operations.

Planes could come in to land on both runways at the same time during busy periods, Heathrow has proposed, to help maximise its capacity ahead of expansion.

The plans, requiring planning approval but tacitly backed through government support for increased aircraft capacity, would involve lifting the current cap to more than 500,000 flights a year. New areas of London would be brought under Heathrow flight paths for the first time.

The airport will also start to sketch out where planes will fill the skies after the third runway opens, potentially as early as 2026.

In a separate consultation last year, most respondents rejected the idea of concentrating more planes over the same area and asked the airport to vary flight paths, which is likely to affect thousands more homes.

However, more distant areas under flight paths, such as parts of south-east London, could get some respite.

John Stewart, of the Heathrow noise reduction campaigning group Hacan, said: “Although a third runway will clearly bring many losers, one long-lasting impact of these proposed changes is that a break from aircraft noise would be guaranteed to many more people than who currently enjoy it, as Heathrow would make the biggest changes to its flight paths since opening in 1946.”

The consultation will ask how to alternate runways to best manage respite from noise, including on night flights.

Heathrow has agreed to a six-and-a-half hour night flight ban, which could mean the first planes touch down as late as 5.30am, if it was to use two runways, or 5.15am if using just one.

Emma Gilthorpe, Heathrow’s executive director for expansion, said the airport was committed to delivering the third runway scheme responsibly and urged local residents to have their say. She said: “It is crucial that our plans maximise the benefits of expansion across the country, including for the communities closest to us.”

Councils for neighbouring communities are joined in a legal challenge to the third runway, one of five applications for judicial review of the decision to expand Heathrow that are due to be heard in the high court in March.