Let's use the classical example of a black hole: A massive planet that has shrunk tremendously, until the escape velocity at its surface is greater than the speed of light. If you were sitting on the surface of said planet, would it still be possible for you to escape? Let's say you had a jetpack. The thrust of the jetpack just needs to overcome your weight. As you are propelled upwards, the gravitational field strength decreases. If you can sustain jet propulsion, could you eventually escape this "black hole"?