Has anybody an idea, what the purpose of this flight pattern could be?
DIBWF / Hex: 3E1C2D
Type: C402
CESSNA 402 Businessliner
Type Desc.: L2P
Squawk: 0021
Groundspeed: 258 km/h
Baro. altitude: 1135 m
WGS84 altitude: 1219 m
Pos.: 52.190°, 11.102°
Aerial mapping using photography or lidar.
The aircraft belongs to “Geocart Herten”. They are doing mapping and other services.
Very interesting. The area has been scanned multiple times already 10 … 15 years before.
After your hint to Geocart, I had the impression the following does handle it. But this already old stuff:
https://www.lgln.niedersachsen.de/startseite/wir_uber_uns_amp_organisation/organisation_amp_kontakt/rd_braunschweig_wolfsburg/eine-reise-in-die-vergangenheit-mit-den-laserscandaten-des-lgln-192779.html
Perhaps a re-scanning with more recent sensor technology, or an extension of the old area.
These scans are repeated often. They are also used to check for added buildings, roads etc.
The data is used to adapt maps or navigation systems.
I am living west of Frankfurt Rhein/Main and i see these flights pretty often, at least once a year in different areas
Here is a plane doing the same near Melbourne Australia today
The same aircraft, VH-ZIH, flew out of Bankstown NSW yesterday and did a number of “jobs” on the way to Victoria
The day before in NSW
and the day before flew down from Queensland and mapped south of Sydney
Interestingly, Flightaware shows no flight information at all. These tracks came from ADS-B Exchange.
It’s common, that several flights are not monitored on Flightradar (where your link goes to). Flightradar filters several aircraft for different reasons (e.g. Military flights).
I see pretty often flights/aircraft on my local map, but they are not shown on Flightradar.
Other interesting aircraft are shown, e.g. these ones:
They belong to “Gesellschaft für Flugziel-Darstellung”.
These are often used to display training targets for other military jets or ground-to-air defense systems.
Not sure if i would feel well in such an aircraft knowing that i am the target of an air-defense system 
