Target visibility

Perhaps dots are not the answer but I doubt that one can compare the visibility of a comparatively large aircraft (DC-3) to the visibility of a small aircraft that is only half the size or less.

To be honest I sometimes look up when I see some condensation trails and I do see the plane but could not tell its type (well they all look the same anyway) nor do I distinguish many details knowing that they fly at 11 km and basically are huge compared to the planes we consider here.