The leaders, who comprise the London First organisation, also recommended greater noise protection for Heathrow residents, and for Gatwick and Stansted Airports to be freed from economic regulation by the Civil Aviation Authority.
The recommendations came in London First's submission to the Whitehall-appointed Airports Commission which will make its final report to government in the summer of 2015.
London First said that, in the absence of any long-term strategy to build new runways, priority must be given to finding ways of increasing flights through more intensive use of existing runways.
It estimates that Heathrow could support 10% more flights while reducing delays, and that Gatwick and Stansted could attract more airlines and passengers if existing price controls were abolished and the quality and capacity of rail services to both were improved.
London First chief executive Baroness Jo Valentine said: "We face fierce global competition from rivals who are increasing their air links to new and established markets. In the absence of a long-term plan for new runway capacity to meet that threat, we have no choice but to make the assets we have work more intensively.
"Without decisive action and the changes we recommend, the growing economic cost of deferring new runways - already too great - will not be halted."