Hi Huub,
Started to read the Nuclear(energy) Act" (Kernenergiewet) , this mention a limit of 10e5 Becquerel for Radium. I found a document which puts a wristwatch at aprox a maximum of 0.2 uCu which would put it within the limit but an aircraft instrument will use a lot more radium.
Have you ever done measurements on aircraft instruments ?
I slightly disagree with your conclusions about "working with" is the same as storage and the same as possesion. If we take Mercury as an example. You are allowed possesion of this material, but if you store it in such a way that it will harm your surroundings , that is nature , people , animals etc you will be in violation of the enviromental act.
Please correct me if I am wrong.
Greetings, Pim