GrauGeist
Generalfeldmarschall zur Luftschiff Abteilung
Prior to planning a mission, they get the factory's location (through methods I mentioned), then it's co-ordinates are calculated and given to the Navigator who uses time/speed in conjunction with compass headings to guide the bomber(s) to the target.I think Tkdog was referring to aircraft navigation, not pre-flight intelligence gathering.
Waypoints are usually based on landmarks (lakes, villages, geological features, etc.) and roads/rail lines also aid in their ingress/egress.