After a certain age it's not normally worth insuring the hull if you have a large fleet (and thus a potentially large insurance bill) to spread the risk. The same applied to the 20-year old 747-100 BA lost in the first Gulf War in 1991 in Kuwait (which is why they offered all sorts of incentives to get it back before it was lost to target practice). You have to ensure however that the accountants make some provision in the accounts for this, to avoid impacting profits reported for the year.