Right now, when taking off from a planet or moon, you have to exceed 2km before the mass-lock light goes out. Once that’s gone the FSD can be used to go into SC or jump to another star (if you’re in line-of-sight with it).
Atmosphere would change that (I would think). I know this’ll be guesswork, but what do people think of taking off from any king of atmospheric world: should we still be able to activate the FSD at 2km+ altitude, or should the disruption of the air require us to actually get out of the atmosphere before the mass-lock light goes out?
Remember: this is a “what if” topic. Thoughts?