London Mayor Boris Johnson today launched his strongest attack yet on Government aviation policy, saying delays making firm decisions set a course for "economic catastrophe".
He described the Government as paying "lamentable attention" to the pressing issue of more airport capacity.
And Mr Johnson said a third runway at Heathrow airport was not the answer and what was needed was a four-runway airport, possibly in the Thames Estuary and possibly at Stansted airport in Essex.
The Government has appointed former Financial Services Authority chief Sir Howard Davies to lead an independent commission into airport capacity needs.
But his final report is not due until summer 2015 - after the next general election.
Addressing business leaders in London today, Mr Johnson said the Davies timetable was "far too slow" and that the "continued inertia" was being fully exploited by the UK's European rivals.
Mr Johnson said: "The Government programme to address the looming aviation capacity crunch in the UK is far too slow and I am hugely concerned that their intended timetable sets a course for economic catastrophe.
"This continued inertia is being fully exploited by our European rivals who already possess mega hub airports that they intend to use to erode our advantage."
He went on: "I will continue to work with the Government and the Davies Commission, but the urgency of the situation and the lamentable attention that the Government has paid to this pressing issue has forced me to accelerate the work that I will do to develop a credible solution."
Mr Johnson said a third runway at Heathrow - believed by some to be the Tories' eventual plan - would only be an interim solution.
He added that the scale of the location required - accommodating at least four runways - meant that several locations, constrained by available land, had to be ruled out. These included the existing airports at Heathrow, Gatwick, Birmingham and Luton.
Mr Johnson said that the total cost of building a new, 180 million passenger a year hub airport - including terminals, runways, ancillary facilities and rail and road links - was estimated to be around £75 billion to £80 billion.
He said that under the right conditions, a new hub airport in London could be delivered with private finance and be operated as a commercially viable business.
He said the earliest a third runway could be completed at Heathrow would be around 2026-28, only two to four years quicker than a new hub airport.
Simon Harris has been following his speech.