The well trodden route is to serve some time with the military, then when they decide you're too old, you do the same job for a contractor. the spin off is that the contractor has a constant supply of experienced applicants, pays little for training and a lower salary to take advantage of your military pension! Very similar to air ambulance and police pilots!
very hard jobs to get in to without the pleasure of many years service with the military (in the UK at least).
Good luck