Let me just throw in one that's a tad silly but not impossible. Let's say some members of Congress are complaining about the black budget and an Air Force general decides a few UFO sightings might just rein that in. So he orders two jets to fly high on perpendicular paths to each other, one 1,000 higher than the other, one with lights off and the other with lights on until they cross paths, at which point one turns off the lights and the other turns them on.