plane sailing /ˌpleɪn ˈseɪlɪŋ/ noun1 •A technique for navigation using the assumption that the journey occurs over a plane or flat surface rather than the actual curved surface of the Earth, which is sufficiently accurate over short distances.I doubt as hovv I've steered by a vvrong chart, d'ye see—as for the matter of the sciences, to be sure, I knovv plain sailing and mercator; and am an indifferent good seaman, […] — 1760
