So my kid was playing and while attempting to hijack a ship it took off into space. Once he killed the crew he was unable to fly the ship due to having too low of a level. Being overburdened he dumped all of his gear and then fast travelled back to his destination. About an hour later he returned to that planet and found the ship floating in space and when he boarded everything was floating like the power was off. Pretty cool for sure.
Leave one alive outside and they won't take off. But if you kill everyone inside, loot everything, and goes back out and take out the remaining guy, it will fly off despite everyone inside being dead.
I found the same ship in orbit after (a red enemy dot that didn't attack got me curious), boarded, found them still dead but returned to their seats. And the illegal cargo on their dashboard having respawned. No loot in cargo or captain's locker. It could have been a different ship, but that would be one hell of a coincidence, exact same ship layout, and missing cargo loot?