Background/History

Allyson Ferraro had been many things: competitive gymnast, honor student, martial artist, base jumper, fighter pilot.  Now, she was dismissed from the Air Force.  Seems that you can't defenestrate a superior officer, even if he is sexually assaulting you.  Well, at least he was also in trouble, so it wasn't all bad.

She looked around for a new job, and got one as a test pilot for Graviton Aerospace, a small aerospace company.  She had expected her dismissal to be a problem; but once she had explained the circumstances, she was hired on the spot – the boss liked her story and attitude.

Their big project was an anti-gravity engine, a new design which they hoped would be efficient enough to compete with conventional airliners.  The prototype was an old business jet, with the engine taking up most of the cabin, and retaining the jet engines.
On one of the early test flights, they were powering up the engine during flight to make sure it would work in flight without any problems.  But something went wrong; the power kept building up until it released in a large gravitational pulse and EMP, throwing the plane into a tumble and destroying all electronics on the plane.  Allyson was somehow able to regain control of the powerless plane and make a controlled belly landing; she was lucky that it was an old enough plane to have backup mechanical links to the control surfaces.
Other than being shaken, she seemed fine after the accident.  It was only later when someone pointed out that she was floating a couple inches off the ground that she realized something had happened on that flight.  Some experimentation revealed that she could fly with amazing speed and maneuverability, which she thought was fantastic.  It was something that she had always wanted to be able to do.  Slightly later, after realizing that she still needed to breathe and wasn't immune to the cold, she got Graviton to make her a flight suit.  She didn't ask for armor, but they put it on anyway – extra protection never hurt anyone.
And while she wasn't looking to become a superhero, her sense of duty and responsibility kept dragging her into it.

Personality/Motivation

She is a thrill seeker and speed junkie, no doubt.  Which can conflict with her focus, dedication, and sense of responsibility.  It can be hard to predict which impulse will win out in any situation.
Having made her way into a very exclusive boy's club, she can be quite stubborn and determined.  She also takes very little grief.

Powers/Tactics

They accident with the anti-gravity engine somehow gave her powers over inertia and kinetic energy.  This lets her fly at either high speeds or with seemingly perfect maneuverability.  It can also let her impersonate a brick, bleeding off energy from attacks against her and lifting heavy objects.  Also, despite easily being able to fly into space, she possess no inherent abilities to survive there, hence the fancy spacesuit/armor.
As for tactics, she's pretty straightforward at this point - hit them until they stop moving.  She likes to keep moving and using her superior mobility to assist in the hitting.

Appearance

Her armored flight suit is white with blue trim.  It consist of armored plates over a skin-tight pressure suit, which is vacuum-rated.  A bulge on her upper back holds the life support equipment.
Out of costume, she is a fairly attractive young woman, with the powerful build of a gymnast.  She'll dress up nicely while on business, but otherwise favors clothes suitable for getting active in.