The British Airports Authority (BAA) is to spend £6.8bn to improve capacity at London's three main airports.
The number of air passengers is expected to rise for a decade
Changes include allowing Heathrow to receive the new Airbus 380, the world's largest passenger aircraft.
BAA predicts a 3% a year rise in passengers using Heathrow in west London, Gatwick, West Sussex and Stansted, Essex, over the next decade.
It said its forecast did not take into account the proposed runway extensions which would increase flight numbers.
There are plans for a second runway at Stansted to be ready around 2011, and a short, third, runway at Heathrow in 2015.
The authority said it expected Heathrow's annual passenger total to increase from 67.7 million in 2004-05 to 86 million in 2014-2015.
Gatwick's numbers over the same period were likely to rise from 32 million to 41 million, while Stansted's numbers could rise from 21.2 million to 35 million.
Last year saw passenger numbers rise 6.5%, partly due to the boom in low-cost airlines, and renewed confidence in air travel after the 2003 Iraq war and the Sars crisis.
BAA is spending £2bn of the £6.8bn announced on Thursday on Heathrow's partly-constructed fifth terminal, which is due to open in 2008. The project has an overall budget of £4.2bn.
BAA chief executive Mike Clasper said: "These strong traffic growth forecasts support both BAA's view and the government's view, as outlined in the aviation White Paper, that the demand for air travel in the UK will continue to grow."