The person is correct. I have not seen anybody in USAF wear the nylon version with the knit collar in the last 10 years I am a Danish pilot and when I was a student (In USAF) in 92 we got the nomex version and now that I am an instructor in USAF we still get the nomex version. It wouldn't make sence at all for an aircrew to wear a nylon jacket. It wouldn't protect you in a fire - more the opposite - be a death trap.