Be wary of using Mk14 (or any RAF flying suit for that matter) and "Nomex" in the same sentence, it might give a false sense of security. Once they've been in the washing machine a few times they aint Nomex any more - unless you get them reproofed.
I agree with Jaguar Fan Club. While I have no idea of what specific fabric is used to create RAF-issue flight suits, it is my understanding that the fire-resistant properties of genuine Nomex IIIAŽ garments are unaffected by repeated washing (see generally
here).
