[Stefan]

The german word should be Sinkpfad. Literally descend path. In todays aviation they use
4 lights next to the touchdown zone. 2 white lights and 2 red lights means
on descend path. More red lights means too low, more white lights too high.
It is a visual aid to maintain a stable approach. It is possible that similar
devices were used by the Luftwaffe.

Stefan