Lots of Corsica demand this summer, and BIA is the only Corsican airport that can welcome 777s (CLY and FSC have no capacity for LH aircraft, and AJA can go to A330 maximum due to runway constraints). Slot constraints at either end (ORY and BIA) means the most practical is to send bigger aircraft
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'd love it if they could rather add more BIA to CDG service though and there is a lot of demand in Bastia for that as well...