Last month, the Scottish travel hub had 776,000 passengers and the London facility accommodated 5.8 million.
In addition, the company's April 2011 traffic figures revealed that punctuality at Heathrow Airport hit its highest ever monthly level.
Colin Matthews, chief executive of BAA, said: "I am delighted that more passengers departed on time from Heathrow than ever before. These figures reflect the results of our £1 billion annual investment and the commitment of 77,000 staff from 320 companies who work at the airport to improve the experience of our passengers."
Furthermore, BAA's March traffic figures also showed that traffic at Heathrow Airport increased by 2.3 per cent, while Glasgow's traffic rose by 2.4 per cent.