The simple answer to your question, when did UA ban smoking?

Not soon enough!

I hate to recall how awful it was to fly back then. The idea that the front of the plane - let alone the crew - would not suffer from the smokers in the back of the plan amazes me to this day. I am not sure if we knew enough about the health risks of second hand smoke back then, but I can recall many times in row 1 feeling too close to the awful odor generated by those in the rear.