Back in my skydiving days we were on climb to altitude when we watched -with great interest - a RAAF Caribou (known in the US as the C-7?) pass by.. we had a great view as we had no door on that side...
I would have sworn it was much less than 1000 of altitude separation... our pilot said it was more.... Amazing how much detail you can make out at a slant distance of not much more 330 yards!