Transporting Your Lifejacket by Aircraft
The International Air Trasport Association (IATA) is the governing body that creates regulation for international air transport. Under IATA rules, a passenger is permitted to transport automatic life jackets in the aircraft. They also allow the carriage of 2 spare cartridges.
If you are intending to take a lifejacket with you when flying, the CAA recommend that passengers contact their airline when booking their flights and obtain written confirmation of the airline's policy on the carriage of lifejackets and their inflation cartridges. Allow yourself additional time to check in.