Originally Posted by
xliioper
It depends on origin country for refundable fares. Currently, US/Canada origin fares have no requirement you cancel before departure to get refund on refundable fares. For EU origin fares, if you fail to cancel before departure on refundable fares, they become non-refundable (from the Penalties section of refundable EU origin fares below).
That's interesting, as it means you just lose the refundability of the ticket, as opposed to losing the value of the ticket.