2009 was a tough year for airlines
The UK's airports handled 7.4% fewer passengers last year than in 2008, the biggest annual decline since records began 65 years ago, figures have shown.
The Civil Aviation Authority (CAA) said that with passenger numbers having also fallen in 2008, it was the first time levels have fallen two years in a row.
It said last year's decline was led by a fall in holiday airline traffic, with charter flights down 17%.
A total of 216.8 million passengers flew last year, the fewest since 2004.
UK domestic flight traffic was down 8% and overall scheduled airline traffic fell 6%.
"Today's figures show the biggest fall in passenger numbers since the Second World War, highlighting the enormous impact the recession has had on the aviation industry," said CAA economic regulation director Harry Bush.
"Passenger numbers are now back to the level they were six years ago and, although they will certainly rebound, the pace of recovery is uncertain and it could be a number of years before they reach their peak level again."