First thing is that avalanche backpacks with pressurized gas cartridges are 100% legal to be transported on an aircraft and they are certified by IATA – an organization that certifies goods to be flown by plane. Most common systems are the BCA Float system, RAS (used most commonly by Mammut and a couple other brands) and ABS – and all of them work on a pressurized cartridge basis.

So just after you book your ticket, it is a good idea to contact the airline customer support and inform them that you will be travelling with such a backpack. On one of my flights I booked a ticket through some third party broker, as they offered good prices, but had some problems with customer support and no one was informed that I carry such a backpack.