Board Thread:Questions and Answers/@comment-78.202.184.197-20170623135257/@comment-27384850-20170623154431

None of those characters are able to fly, it's actually a major plot point in the first volume that Silver Crow's unrestricted flight is the first of its kind to ever exist in Brain Burst. Black Lotus hovers due to the nature of her avatar's limbs but does not fly, Lime Bell can't fly at all, Sky Raker has thrusters with very limited propulsion (she could only ever get a few hundred meters into the air and immediately fell back down), and White Cosmos is similar to Black Lotus (I think, I've not read that far).

Silver Crow is the only avatar with a true flight ability, even in the Accel World series.