London Heathrow appears more than any other European airport on Eurocontrol's top 20 list of "most delayed airport pairs".
The UK hub features five times as the departure airport, and six times as the arrival point.
Heathrow is second only to Lisbon for average delay to all its departures, and top of the list for delays on arrival. Flights from the Portuguese capital depart an average of 14.6min late, and from Heathrow 13.1min, but Lisbon is improving its rate while Heathrow's is getting worse, says Eurocontrol's Central Office for Delay Analysis (CODA) report for 2013.
London Gatwick is third in the list with an average departure delay of 12.8min, and its delays are also worsening.
Among the delayed flights from these airports, Lisbon passengers experience an average delay of 30.3min, Heathrow passengers 26.5min, and Gatwick passengers 27.8min. Three more UK airports are in this departure-delay top 20: Manchester in fifth, London Luton ninth, and Birmingham 13th.
The top three European airports for arrival delays are Heathrow, Lisbon and Gatwick, with average arrival delays of 14.6min, 13.1min and 12.8min. Passengers inbound to Lisbon whose captain advises them of an inevitable delay can expect to land 30.3min late, Heathrow passengers 26.5min, and Gatwick passengers 27.8min. UK features prominently in this list, with Manchester fourth and Luton 14th.
As for the most delayed routes, the worst is departures from Lisbon to Madeira, with Lisbon to Heathrow coming second. But Heathrow appears in the next three entries, either as the departure or arrival airport: Rome Fiumicino-Heathrow, then Heathrow-New York JFK and JFK-Heathrow. Malaga-Gatwick follows in sixth.
The CODA Digest states: "London Heathrow features prominently in the top delayed city pairs, with the airport seeing weather delays throughout the year. Arrival flights experienced delays with knock-on reactionary delay being observed on departing flights."
This suggests that Heathrow suffers from having no slack in its movement schedule.
London's runway capacity is the subject of an Airports Commission report, but no decision is to be made on its recommendations until after next year's UK general election.