Gatwick Airport insists it remains a "credible and deliverable option" for runway expansion after recording almost double-digit growth in passenger numbers last month.
Some three million people used the West Sussex airport in February, up 9.9% on the same month in 2016 despite there being one day fewer.
Its long-haul routes were up 20.3%, while cargo grew by 6%.
Gatwick chief executive Stewart Wingate said: "Gatwick's February passenger figures demonstrate the confidence we are witnessing from our passengers, with travel still high priority following the Brexit referendum."
He went on: "Our long-haul growth is driving the natural corresponding cargo increase, this month plus 6%, which is joined by strong growth in Gatwick's regional connections across Britain, demonstrating Gatwick's vital economic role both within Britain and internationally, as we continue to offer the UK Government a credible and deliverable option for runway expansion."
Demand for Gatwick's Los Angeles flights increased by 90% compared with the same month last year, and passengers will soon have another option for travel to the US's west coast, with British Airways starting its new route to Oakland, California.
In February the Government published a consultation on its draft national policy statement which set out why a third runway at Heathrow is its preferred option for boosting airport capacity in south-east England.
The west London hub welcomed 5.27 million passengers in February, up 1.7%.
The airport said the growth was due to the use of larger, fuller aircraft.
Heathrow chief executive John Holland-Kaye said: "Heathrow is off to a flying start in 2017. We're delivering the best service of any major airport in Europe to record numbers of passengers and boosting British exports with record cargo volumes."
Manchester Airport recorded its 35th consecutive month of growth with an 11.1% rise in passengers in February, reaching 1.66 million.
Charlie Cornish, chief executive of Manchester Airports Group, which owns the airport, claimed the figures demonstrate the need for the Government to improve transport links across the North.
He said: "Manchester Airport is continuing to show its importance in providing global connectivity to a wider and wider segment of the country.
"No other airport outside of London can come close to offering the range of global destinations that we offer from our two runways.
"Now is the time for Government to start making concrete plans to improve access to the airport for the whole of the North.
"Businesses to the east and the west, particularly in key northern cities such as Liverpool, Leeds, Bradford and Hull, would benefit from more rapid and convenient rail links to a globally connected airport."