How do I unlock Large aircraft contracts?

Recently I noticed at Innsbruck airport I can only get Small to Medium Aircraft contacts, does anyone know how to upgrade to larger aircraft slots as I am getting bored with small to medium all the time.

I am playing on my poco x3 pro phone by the way not a laptop or tablet.

INN can only have S and M
BRI can only have S and M and L
The rest can have all

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INN only have S or M, so if you want L, you can play BRI for L and the rest of the game also have it too + XL