Keeping a passenger aircraft at constant speed of 600 mph is not realistic with the current (or near-future) battery technology, even if the initial kinetic energy comes "for free".
May be it's a rocket. You just stand in a small rocket vertically, like those used in the military and cost about 3-4 million each. You get launched to 10-15 miles height making a gravity turn at some point. After that it takes a relatively small burn to secure a nice trajectory that lands you 500 miles away. I imagine it's a vertical pipe 1 mile high and you stay on your feet the whole journey with about 5g being accelerated in the pipe until you reach the proper delta-v. Then you land with parachute on cushions or grasshopper-style. Worst case may be an electric propeller.