Theory:Doctor Who television discontinuity and plot holes/The Ark


 * It's rather remarkable that the TARDIS manages to land in the same spot twice (albeit a few years apart) when the Doctor can't control its journey.
 * The Doctor forgot to enter new spacial coordinates, or there was a breakdown in the mechanism, and only the time circuits were activated for this journey. This being the case, the TARDIS followed its default/emergency procedure (See DW: Terminus) of remaining locked-on to the Ark as a 'fixed point', even though it would have moved billions of miles through space in the intervening centuries it took to reach Refusis.