London Mayor Boris Johnson has backed a report calling for a brand new south east England airport.
Overseen by Transport for London bosses, the report said the UK economy would suffer and London lose jobs to its European competitors unless a new hub airport was created in south east England.
Mr Johnson said for London to remain at the centre of global business "we need aviation links that will allow us to compete with our rivals".
Daniel Moylan, deputy chairman of Transport for London, oversaw the report which was released on Tuesday.
It found, in terms of destinations served by worldwide international airports, Heathrow had fallen from second in 1990 to seventh in 2010.
The number of destinations that can be directly accessed from Heathrow stood at 157 compared to 224 from Charles de Gaulle airport in Paris and 235 from Frankfurt, it said.
It concluded this showed London's only hub airport was losing out to other European airports which, if sustained, could have long-term damaging effects on both the London and UK economies.
Mr Johnson said: "The capital's airports are full, our runways are rammed and we risk losing jobs to Frankfurt, Amsterdam, Madrid or other European cities should we fail to act.
"No other city even approaches the volume of passengers handled at London's airports but we need to start planning for a brand new airport that can help meet the ever-increasing demand for aviation and act as a hub, particularly to the rest of the UK."