I have yet to see a biotic fly. slow a descent yes but not fly.
Which is weird in itself don't you think? I mean the property of Biotics and the mass effect technology is being able to manipulate mass (also known as weight) with E-zero. And some kind of voodoo for Biotics. But you can't slow down your decent by decreasing your mass. Since objects which are very different in weight accelerate just the same. Okay you might argue that you have so much air friction that you wouldn't fall as fast. But I don't think you could decelerate a human shaped body that far. Even if it has one percent of it's initial body weight.
I could be wrong though, I'm not so good at friction calculations.
As for flying up, that seems to make no sense at all. I mean the way they portrait it there was no jump at all to make accelerate the body. And since a mass decrease would still need that initial push to get you somewhere. I haven't seen any movement like that, but the mass could be lowered enough to make this possible by a simple movement.
Now that I think of it, buoyancy could also work. But I would need the weight, atmospheric composition and pressure of the atmosphere and body volume to calculate what kind of mass the biotic would need to simply glide up.