Boris Johnson has attempted to resurrect the possibility of a new airport in the Thames Estuary.
The so-called Boris Island scheme was officially rejected by the Government-appointed Airports Commission in September 2014.
But the mayor of London's office has published a report which claims a four-runway hub either in the Thames Estuary or at an expanded Stansted Airport in Essex is the only way to secure the number of new routes required to boost the UK economy.
Mr Johnson believes a hub in the east of the capital would offer around double the number of long haul and domestic routes served by Heathrow while exposing 95% fewer people to significant aircraft noise.
He said: "If we are to secure the connectivity we need to support our future growth and prosperity - and do so without dire impacts on public health - then we must do better than Heathrow."
The Government is assessing whether to back expansion at Heathrow - the Airports Commission's recommended option - or Gatwick.
The 78-page document produced by the mayor's office - entitled Landing The Right Airport - says a four-runway hub would serve 114 daily long haul routes in 2050, compared with 75 at a three-runway Heathrow.
A report prepared for the commission warned that the estuary plan posed a "significant cost and risk to the taxpayer".
But the mayor's chief adviser on aviation, Daniel Moylan, told the Press Association the burden on taxpayers of a third runway at Heathrow would not be "very much lower" than the cost of a new airport.
He said an estuary airport would cost around £20 billion to 25 billion - with an additional £25 billion required for road and rail connections - while a third runway at Heathrow is estimated to cost £18.6 billion.
The mayor's report calculated that the surface access improvements required to enable Heathrow to expand without "significant consequences" for congestion and crowding would be more than four times the figure estimated by the Airports Commission, at up to £20 billion.
The commission did not take into account necessary schemes such as a direct rail link between the west London airport and Waterloo station or the cost of maintaining new roads and tunnels up to 2050, according to the mayor's office.
Mr Johnson said: "We need a long-term vision for the right airport that sustains our economy and safeguards our public health. I would urge Government not to turn its back on our future."
Asked about the probability of the estuary airport going ahead, Mr Moylan said: "The likelihood of closing down Heathrow - and these arguments will help in doing that - is quite high.
"After that, everything is up for grabs."
Mr Johnson, the Tory MP for Uxbridge and South Ruislip - near Heathrow - is stepping down as mayor in May.