Two of London’s five airports recorded problems with punctuality in the first quarter of this year – with 44% of flights at Heathrow experiencing delays.
Figures from the Civil Aviation Authority also show just 58% of flights took off and left on time at London City Airport.
However, London's other three main facilities - Luton, Gatwick and Stansted - all saw improved service reliability compared with last year.
The average delay endured by a passenger passing through one of the UK's main airports now stands at 18 mins, up from 16 mins during the same period last year.
Airport owner BAA blamed increased passenger numbers and adverse weather for the delays.
The airport runways are "operating at 100% of capacity, which means small events such as adverse weather, can cause major delays and disruption," the spokesman said.
"Other airports, which have plenty of spare runway capacity, do not suffer these problems."
By Elizabeth Clifford-Marsh
