I would have thought that the worst months for upgrades would be between June and September (people flying for summer vacations) and the Thanksgiving to New Year's holiday crush.

But Matt and others make good points: those trying to requalify and those trying to use those final upgrade certificates.

One more reason why feb/march difficult for upgrades: It's spring break and the college students and their teachers are trying to get away and the smart ones want to do it in first class.

This may be a minor reason but certain flights to the "college break" destinations are very very booked. CATMAN