surely so, but in the odd case that even one single image might have a plane on it, on the path the OP currently discusses here, might be enough to confirm further travel. the full step-by-step transition of the plan wouldn't even be necessary. just one shot with that plane. from somewhere.

Global? Likely. Realtime? We're not quite that far into the future. Just try and estimate the bandwidth for the biggest security camera of all times: at 1-3 meters resolution per pixel, worldwide, that's a lot of pixels (about 510 072 000 000 000 per frame, give or take - that comes out at about half an exabyte per frame, if I'm not mistaken). Take ten of these, and you've generated as much data as the whole Internet does in a day. Oh, and you also need to store it somewhere, but this is a minor issue (in comparison to the above).