The Falcon 9 first stage releases stage 2 at around 6-10 times the height and 10x the speed. That said, remember that the difficulty of elevating yourself abov

The Falcon 9 first stage releases stage 2 at around 6-10 times the height and 10x the speed. That said, remember that the difficulty of elevating yourself above a given height is much worse the lower you are. Using a plane-drop means skipping the very worst parts of the launch. The air is so much thinner. There's other advantages though. Launch windows get much easier, as the plane can fly in any direction, and stay at a given heading a bit longer.