The number of passengers handled at BAA's six UK airports rose 3.8pc last month compared with January 2010, the company announced today.
The January 2011 figures were boosted by a strong performance at Heathrow airport and by the fact that the January 2010 passenger numbers were affected by snow.
A total of 7.5 million passengers passed through the six airports in January 2011, with Heathrow numbers rising 4.6pc to 5.05 million.
This was Heathrow's highest January figure since 2006 and its strongest long-haul performance ever.
Stansted airport passenger numbers fell 5.8pc last month, but Edinburgh was up 13.6pc, Aberdeen rose 9.1pc, Glasgow increased 8.0% and Southampton had a 4.8pc rise.
European scheduled traffic rose 2.7pc while North Atlantic numbers increased 3.2pc.
Other long-haul routes rose 4.5pc, including increases of 30pc on routes to China and rises of 10pc on Indian services.
The January 2011 figures follow the troubled month endured by BAA in December 2010 when the company faced widespread criticism for the long delays for Heathrow passengers trying to get away for Christmas during the early-winter bad weather.
BAA chief executive Colin Matthews said today: "Passengers want quality service at our airports, from the beginning to the end of their journeys. The better we collaborate with airlines and ground handlers, the better the experience will be for customers both in normal operations and during disruption.
"We are working with all of the companies at Heathrow and elsewhere to improve passenger experience and make our airports more resilient, building strong contingency plans."
He went on: "The underlying performance of our airports is strong, reflecting an improving economic environment.
"In particular, Heathrow's strong performance and our £5bn investment programme is good for the British economy and for passengers. In Scotland, we can see encouraging signs of growth, reflecting investment in new routes and we are pleased to see traffic at Southampton increasing."