" …it was even more disconcerting to examine your charts before a proposed flight only to find that in many cases the bulk of the terrain over which you had to fly was bluntly marked: ‘UNSURVEYED.’ It was as if the mapmakers had said, ‘We are aware that between this spot and that one, there are several hundred thousands of acres, but until you make a forced landing there, we won’t know whether it is mud, desert, or jungle – and the chances are we won’t know then! "

― Beryl Markham