One of the most exciting features in Aion is flying. Unfortunately the same feature is usually the cause of XP loss. If you fly too high the wings on your minimap will turn purple which indicates that you will not survive the fall. When the wings are blue you will land safely (The image above demonstrates the wing color difference).
If your flight timer runs out while your wings are purple, don’t try to fly or to glide again before you are very close to the ground. These few seconds while falling down will be enough to get few flight ability seconds and you will be able to spread your wings just before you hit the ground and survive the fall.