thanks for your reply. With peek it is an interessting possibility.
Sadly this will not lead to the aim. My easy table example shows only a Rotation for one plaine. In real the Nodes, that describe one flight and the ParentNode is the only link to the flight before. With multiple plains all flight IDs are mixed up depending when the flight got stored in the respective system. Ordering the flight ID is possible, but sadly it does the still not help me to create the Clusters.
Beside a Cluster identifyer i would like to transform the Flights to a horizontal reading like "FRA-DKR-EZE-MVD-VCP-DKR-FRA"
With the following function thie is working, but if the clustering i did not get it