No you cannot book a flight a year before your travel. The GDSs (reservations systems) that the airlines use does not specify year: only the date and the month. There's no place in the search format to enter the year.The max advance you can search is 331 days in advance. Even though it is probably possible for the airlines to reprogram their systems to allow a larger booking window, it hasn't been worth their while to do so. Most people book much closer to departure, so even though they would collect your cash up front if you could book farther out, it just sits on the books as a liability until you actually fly the trip and it gets converted to revenue. Even by chance if you book a ticket extremely well in advance and if it's 355 from the outbound, you won't be able to book the return yet.