How do you set the Current Speed variable? Normally you would do that by getting Velocity and getting Vector Length from that, but since your velocity is always 0,0,0, as you say, where does the Current Speed come from?
But I believe you can use that. You can get your Plane’s Forward Vector, multiply it by your Current Speed and you will have your velocity. But that will only work correctly if your Current Speed value actually corresponds to the Plane’s Velocity.