One of the more difficult tasks is actually getting ``the picture you want''. It isn't unusual at first to knock off a 24-roll of film and find that none of them turned out well, or missed the target entirely! For downward-mounted cameras, the plane must simply be over the target high enough to capture the target in a single frame, and the camera setting must be correct. But this easier said than done! Air currents rock the plane during flight, and a small deviation from straight-and-level is sufficient to point the camera in the wrong direction and miss the target entirely. Furthermore, from the ground it is difficult to determine when to trip the shutter unless you are standing on the target and the plane is directly overhead. Perspective matters. It is dramatically easier if you can place yourself at the target. Alternatively, if an assistant can walk to the target, [s]he can communicate when the model is in the right position to take the photo. If neither is possible, some trial and error will be necessary until you get the hang of it.