I have traveled three times on domestic flights in the last fourteen months with my Gitzo series 2 Traveler tripod fastened to the exterior of my camera backpack with no issues whatsoever. On two international flights in the last nine months, I opted place my tripod in a checked bag to avoid having any problems. My tripod does have rubber feet if that makes a difference and I do not have TSA fast track or whatever they call it, I just stand in line with the general population.

Coming from Las Vegas two years ago a couple stopped and asked me was I really going to keep my tripod strapped to the outside of my camera bag during bag screening as we sttd in line. The two were amazed as I went right through with no problems. I learned they were both forced to "check" their tripods on trip they took just a few weeks prior (at the same airport).