It might help to remind yourself that the feeling of being trapped is not the same as being trapped; ask yourself if you are actually trapped in reality - or if you could easily exit the line and come back in a few minutes.

One part of reminding yourself is to tell yourself that 'thoughts are just thoughts' and we don't have to act on thoughts. That might help you feel calmer in the moment because I think the panic comes from the idea that we need to 'do' something when we really don't need to do anything. We are reacting to our thought, and 'thoughts are just thoughts'.