Originally Posted by
JHewAtNEU
I'm not 100% sure, but it seems that GAs are instructed to upgrade Mosaics if EMS seats are avilable. I've never had to pay for a seat and get one 100% of the time. I usually go up ~30m prior to boarding and ask if there are EMS seats available, show my current boarding pass, and boom - new boarding pass.
I didn't realise it was that common...will definitely ask on my trip in two weeks! Thanks!