Ive dont it several times recently. You can check or carry it on. The size of Lithium battery
is not an issue and it is installed, which is the key. The whole issues is non installed lithium batteries
What I've done:
Print out the airline hazmat poilicy on batteries ( they are all the same and found in FAQ's- they follow the IATA regs)
Look up the manufacture web page or call them and ask for the MSDS for the EPIRB
. I carried it just to prove the type of device and size of battery
Never been questioned or hasseled.
, I may have the MSDS