BAA's seven airports have experienced a combined drop of 2.6% in passenger traffic in September 2009 compared to the same month of last year.
The airports handled a combined 13 million passengers in September.
Heathrow Airport showed a marginal decrease of 0.3%, while Gatwick saw a decline of 0.5%.
Edinburgh Airport saw a 3.8% growth in passenger traffic, but London Stansted Airport saw a decrease in passenger traffic of 11.6%, which was caused by a 11% reduction in seat capacity.
Southampton saw figures fall by 4.6%, while Glasgow Airport also experienced a drop of 8.9% and Aberdeen by 5.3%.
The group's air transport movements saw a decline of 6.1% in September.