As I understand it, Halon is now banned as a fire extinguisher and existing installations have to be dismantled (don’t know what date). It’s often used in buildings (floor voids etc) and electrical equipment cos it kills fire quick and leaves no mess (unlike powder) but it can suffocate you in a confined space, though not a poison (as such). Aircraft are exempt – for the time being. If you can get it, use it – it is the best if you can only have one type and it has to be small.
If it's a big fire - run.
Gerry