I’m sure we can make something up that makes sense.
I guess when it’s parked no one can find it. Also if it’s invisible to radar then she’d just look like a cloud or bird or something.
Also Superman got to fly on his own, so it’s more…fair if at least her plane is invisible…?
Radar is a kind of electromagnetic wave, and so is visible light. If the plane were invisible to all EM radiation it would be invisible to both the eyes and to radar.