This achievement requires you to travel half a mile using glide, jump, wall run, and air dash without touching the street floor or the roofs of buildings. The easiest way to do this is after you've upgraded your air, dash to the highest point - and your jump ability also. Head to the Empire State Building in the Red Zone, and then have at it, running up the side of the building, jumping off the side, and gliding for awhile, then returning once your glide becomes too steep and repeating this until you've earned the achievement, which shouldn't take too much time. It seems hard at first, but it really isn't. Note that you can do this with any tall building. I just chose the tallest as the best example.