#40 is my favorite of your submissions so far. How about making the inner white line a bit more like an F by darkening the right side vertical line? 30 and 31 reminded me of a heart, but I like the lines used, which might be able to work representing an airport diagram/layout. Also, note the fonts by some of the others. I liked a few that had "Performance" in italics, which was sleek and gave a feel of motion.