Figures published yesterday by owner BAA showed Glasgow had 6.7% more passengers in April than a year earlier, its third consecutive month of growth, while Edinburgh, which is in the process of being sold to Gatwick owner Global Infrastructure Partners, had a decline of 1%.
It is the third month in which passenger numbers have either dropped or flatlined at the capital's airport – largely due to cuts in Ryanair flights – and comes after the airport had appeared to defy a pronounced downturn in aviation that hit the UK in 2008.
Edinburgh now has 9.3 million passengers a year, according to the latest figures, while Glasgow had 6.9 million passengers in the 12 months to April.
Aberdeen, also owned by BAA, continued to enjoy unparalleled growth among UK airports, largely due to a booming offshore oil sector, with 274,000 passengers in April, a rise of 11% on the same month in 2011.
Experts said Glasgow's growth was down to a resurgence in the holiday market, which has long formed the backbone of its traffic, in contrast to the business travel and inward-bound tourism that dominates at Edinburgh.
A rise in flights to sunspots and new routes to major European cities such as Barcelona, Rome and Venice helped cement the network of destinations available from Glasgow, while its long-haul network will be boosted by the addition of a second daily flight to Dubai by Emirates next month.
Amanda McMillan, managing director of Glasgow Airport, said: "Despite the challenges presented by rising fuel costs and further increases in Air Passenger Duty, we have enjoyed considerable success in expanding our route network.
"This has been a major factor in encouraging more people to fly from Glasgow Airport."
Analysis of airline schedules seen by The Herald show the trend is likely to continue, as Glasgow will have 16 new routes launched in August alone, compared to 14 at Edinburgh.
These new routes will account for 226 departures in August from Glasgow, with 119 taking off from Edinburgh.
The analysis, undertaken by RDC Aviation, also shows seating capacity at Edinburgh is set to stay roughly the same between May and October but grow by 7% at Glasgow as more flights are launched.
Much of the additional capacity has come from the Jet2 airline, which has taken advantage of gaps left in the market following the collapse of Flyglobespan in 2009.
Joanna Hunt, an analyst at RDC Aviation, said Glasgow had been hit harder by the recession but was now showing strong signs of recovery.
She said: "Glasgow was hit hard by a drop in leisure travel but has started to come out of the recession and is starting to recover.
"Edinburgh has far more business passengers and has been highly impacted by what's happening to financial institutions in the economic downturn, just simply because of traffic they rely on."
She said some of the recent gains made by Glasgow had been at the expense of Prestwick, which recently reported that passenger numbers had dropped by a third over the past year. The airport has been put up for sale by its New Zealand-based owner, Infratil.
A spokesman for Edinburgh Airport said: "Domestic flights, excluding London, suffered from uncertainty around airline bmi, and European traffic was also slightly down."
Derek Provan, managing director of Aberdeen Airport, added: "I am pleased to report growth in the passenger numbers for Aberdeen Airport during the month of April.
"It marks the beginning of the summer flying season and these latest figures represent a fantastic start to our summer programme."