Originally Posted by number_6

It books into Y on American Eagle (the only AA flights that don't have F available). For other airlines the rules vary from year to year, but I think all book into L now (very annoying) except LA might still be Y (haven't bothered to check recently). This is a nasty feature of xONEx fares (L inventory is both hard to get on some routes and of course earns reduced mileage).