This achievement requires you to remain in the air for about 25 seconds. Early in the game, it's pretty hard to do this since you don't have your air dash ability evolved to its highest yet. Once you do, which will hopefully be when you've reached the Red Zone, travel to the Empire State Building in that zone and head to the top. Quite simply, you can also get the Icarus achievement by climbing up the building's spire. Continuing, you can glide from the Empire State Building's roof - make sure you use your air dash every so often to keep your gliding angle from becoming too steep. You should have the opportunity to use air dash either twice or three times. Either way, you should have more than enough time under your belt once you reach street level. When you land, the achievement should pop up.