Avex or Sonic Flight, is a Legacy that allows the user to fly at high speeds through the atmosphere. It is separate from Levitation, which is the Garde's ability to float through the air using Telekinesis.
It is a Legacy probable to a Loric who come under the Lorien Star Sign Orlin.
Five discovers his Legacy of flight when he attempts to travel to Martinique from the lonely island that he was living on, shortly after Rey's death. After he leaves on a boat and sails for seven days, his food rations and water had run out and he was starving and dehydrated. Suddenly he opens his eyes and realizes that he isn't in the boat anymore, instead he is floating towards the sky.
Five continues to fly until he finds land and he crashes on the beach in Miami. (Five's Legacy)
Ella's mother had the Legacy of flight. She is assigned to keep an eye on Raylan, by the Elders, but he does not trust her. She tries to win him over by flying with his Chimæra and creating impressive lightning displays. (The Fall of Five)
Defenders of Lorien
Young Garde Boy
Sandor mentions that he has heard stories of a young Garde who had Sonic Flight who had overshot Lorien's gravitational pull and ended up in an unbreathable atmosphere. (The Last Days of Lorien)
Has all Legacies.
Lexa tells her story, where her brother was one of the best fliers on Loren. Her brother, Zane, was thirteen when he learned about his ability to fly and it is said by Lexa that he flew with much more speed or grace than the other Garde. When he was testing long distance flight and speed around the planet, Zane presumably crashed into a Kabarak Supply Ship which is what is assumed to have killed him. The death of Zane left his sister distraught and reclusive.