But an operation on so ambitious a scale required detailed reconnaissance by a skilled pilot, able to time an aircraft's flight path, judge when it had reached cruising altitude and observe what visual landmarks could be used to substitute for the crew's navigational equipment and guide a successful hijack to its target. At the barest minimum, a stop-watch and compass would serve to plot the course, but global positioning devices produce preciser results.
Or a remote-piloting system and someone(s) on ground.