Just over four in five scheduled flights were on time at UK airports between January and March, the Civil Aviation Authority has said.
A total of 81% of flights either took of landed on time, compared with 70% during the same period in 2008.
The average delay fell from 17 minutes in 2008's first quarter to 12 minutes this year.
But airports were also less busy, with the number of scheduled flights down by 9%, and passenger numbers down by 11%.
According to the CAA, "on time" is defined as either early or under 15 minutes late.
Heathrow, the UK's biggest airport, showed the greatest improvement, with average delays halved from 24 minutes to 12 minutes and on-time flights up to 79%, from 59%.
London City improved from 66% to 84% and halved its average delay to nine minutes.
The number of charter flights taking off or landing on time also improved, climbing from 61% to 68%, while the average delay fell from 29 minutes to 23 minutes.
At Gatwick, 65% of charter flights were on time - up from 59% - while 82% of scheduled flights were on time, a rise of 8%.
Regional airports also improved the punctuality of charter and scheduled flights, to 71% and 83% respectively.
'Greater efficiency'
Among the top 75 scheduled and charter destinations, passengers flying to Rotterdam, in the Netherlands, were most likely to be on time (91%), while those flying to Istanbul, in Turkey, were the most likely to be late (57.9%).
The longest average delays were to Toronto, Canada, (22.4 minutes), while the shortest were to Luxembourg (five minutes).
The CAA monitors the punctuality of flights at Heathrow, Gatwick, Birmingham, Luton, Stansted, Manchester, Newcastle, Edinburgh, Glasgow and London City airports.
A spokesman for airports operator BAA said the figures reflected the hard work of staff at Heathrow "to maximise efficiencies and make every journey better for passengers".
"The 20% improvement in flights departing on time has in part been helped by Terminal 5 which is performing extremely well and which has enabled greater efficiency across all Heathrow terminals."
