I hadn’t heard of”K2B’s” either, until I entered pilot training in 1970. This was the designation of our flight suits at the time. They were sage green, made of poplin; lightweight and comfortable.
These K2Bs weren’t the most ‘stylish,’ but they sure were comfortable! And they had another feature. When we were in the flight rooms, we would hear upon occasion, “Holliker, turn around,” from the scheduler. What we didn’t realize at first was, the scheduler was looking at the salt rings on our backs to see how many times we had flown that day! Each time we went up, we came back with a salt ring. It you “trip-turned,” your flight suit looked like an ancient tree!
About mid-way through the T-38 program we were issued Nomex (fire retardant) flight suits. The first ones were very ill-fitting and uncomfortable; the later ones were fine. So, now you know about K2Bs!
Of interest: The only time I was ever burned in my flight suit was the night in the Auger Inn (bar) right after we were issued our spiffy, new Nomex flight suits. A bunch of us were using a cigarette lighter on our sleeves to see if the Nomex would burn. It will – it did! Brilliant…