Inconsistency?

There is some sort of agreement among sf writers that it is either impossible or at least inadvisable for a spaceship to switch on its faster-than-light drive when it is very deep in the gravity well of a star. Thus, it is usually regarded as necessary to make a sub-light speed interplanetary journey perhaps to beyond the orbit of Pluto before going FTL. (Larry Niven spends some time re-examining this assumption in one of the later Ringworld novels.)

In James Blish's The Star Dwellers (London, 1979), this limitation on the use of FTL does not apply. One spaceship:

"...rose from the surface of the Earth to the top of the atmosphere with the gentleness of a lift - after which she flicked into Haertel [FTL] overdrive so efficiently that she utterly vanished." (p. 34)

However, in the sequel, Mission To The Heart Stars (London, 1980):

" 'Of course, if we go directly on to the Standing Wave [Haertel overdrive] from orbit, there'll be a planet-wide minor earthquake.' " (p. 106)

In the first novel, Blish, demonstrating that the interstellar vessels of 2050 are unlike earlier spacecraft, uses phrases like "...gentleness..." and "...utterly vanished...," whereas, in the sequel, when he is imagining a hasty escape from a hostile planet, he reverts to the idea that an immediate transition to FTL will have violent consequences. The result, I think, is an inconsistency between the novels.