Originally Posted by
parabellum
In certain countries, unless you are a licenced pilot or Air Traffic Controller, in the course of your duties, using a transmitter on ATC frequencies is illegal, may even be illegal to own such a transmitter, not sure about that. Usually only listening is allowed.
Ummm ... *legally* it is not just the pilot that is licensed (you need a FRTOL or equivalent) ... but also the installation. In *theory* using a hand held transmitter in a plane is not a licensed installation.
That said, I suspect if you had a total radio failure, no one would complain if you used a handheld. One old bag of crap I used to fly always had an Icom handheld by the co-pilots seat, as both boxes had a habit of going off just when you needed them.