First Class is not being added to the Q400. The inventory for Q400s was changed because of the E175's arrival. Sabre does not do well when trying to swap from a 1 cabin a/c to a 2 cabin a/c and vice versa. The solution is to make the Q400 a 2 cabin a/c in Sabre and zero out F since it doesn't exist. This way, should a Q400 be subbed with an E175 or vice versa, Sabre is able to properly handle the new a/c. AS has been doing this for years with the 73Q - look up a flight scheduled on that a/c and you'll see the same thing (F0).