It can go in the hold as long as the straps are all tucked in .. I got a highlander "transit bag" for mine which is like a big rucksack cover with a panel you can zip up at the front to totally enclose the rucksack - here's oneI'd love to go at some time, for the flight do you have to put your rucksack in something or can it just go in the cargo hold with knives and all as it is?
you need to have your knives and axe safely tucked INSIDE your pack though...