it's also interesting that airlines give themselves different schedule times for the same route at same time of day for example LHR-DUB on BA is 1hr 10, on EI it's 1hr 20. Flybe always add about 1/2 hr extra on their flight times to and from BHD which is why they almost never leave the gate on time but arrival on time figures look impressive!
What are the rules for this? How much buffer are they actually allowed to go up to?