Originally Posted by
MSPeconomist
My understanding is that inventory classes can continue to be "available" even if there are no applicable fares such as when it's too close to departure to satisfy advanced purchase requirements for all fares of that class.
Yeah it has nothing to do with the fares that may be available to sell on that flight. There’s a very very very large number of city-pairs a pax could be booking on when looking at that particular segment. Just because there may not be any sub-14 day A/P “I” fares on JFK-FCO doesn’t mean there aren’t on ORD-FCO, LAX-FCO, SEA-FCO, etc., all of which might include a leg on JFK-FCO. (Of course the airline can alternatively address this through married segment availability).
Also, someone may already have an I fare and be looking to change to that flight, which they can do even if there are no current valid I fares for sale, as long as there is inventory. If it’s J1 D1 I0 then they have to pay the fare difference to a J or D fare.