Heathrow, the world's busiest international airport, saw record passenger numbers in September, raising hopes of an air industry recovery.
The airport's owner, BAA, said more than 6.2 million passengers travelled through Heathrow last month, 7.6% more than a year ago.
BAA said much of the rise came from a jump in business travel.
Numbers were also boosted by airlines re-starting routes. Some carriers had cut flights during the recession.
The news follows recent encouraging passenger traffic reports from airlines, with British Airways last week revealing a 4.3% rise in passenger traffic last month - its first increase since February.
BAA now owns six airports - Heathrow, Stansted, Southampton, Glasgow, Edinburgh and Aberdeen - after it sold Gatwick.
Passenger numbers across the six rose by 3.3% on the year to 9.99 million users last month.
Colin Matthews, chief executive of BAA, said: "The growth reflects an improved outlook for our airline customers and an increase in business confidence."
A spokesman for BAA said there was some evidence that travellers were catching up on trips they missed earlier this year because of the volcanic ash cloud crisis.
Heathrow's record performance also signals a pick-up in the long-haul market, with the recovering international economy seeing sharp increases in those flying to fast-growing economies such as Brazil, which saw a 27% increase in passengers, Russia, with a 24% rise, and China, up by 10%.
However, the company said leisure travel was still suffering.
There were further falls in passenger numbers at Stansted - down by 4.3% on the year - with no-frills carriers continuing to cut flight capacity.