Any idea as to what might be going on here? The route looks really strange to me, especially with the circle the aircraft is flying right now. 

https://imgur.com/iO1jASy

The current position can be tracked here live on Flightradar24: https://www.flightradar24.com/TUI2144/2d4bd2ff

It has landed, diverted back to Hannover... The flight history can be seen here: https://www.flightradar24.com/data/aircraft/ly-tre/#2d4bd2ff

Edited September 1, 20223 yr by pstrub

This could be anything, but it looks similar to testing. I've done flight testing for RVSM certifications where you have to fly over certain sensors. You may be accomplishing acceptance flights where you may fly a particular pattern to be able to accomplish all of the checks. There is also ADS testing where you are communicating with a regulation rep that is tracking your aircraft. In the G550, we can align the IRSs in flight. To accomplish this test, they have you fly cardinal directions and make turns in one direction to speed up alignment. It ends up looking like a holding pattern and you fly it til alignment is complete. There are some other avionics tests that you may do that results in weird routing. My patterns would normally look like a large triangle. I have to do certain checks at certain altitudes, go down to battery power, climb up to 45,000 for some pressurization checks, over speed on the way down, stall the aircraft for pusher checks, air start engines, flight control trim checks, emergency extend the gear and then put her back down. You accomplish it all along the triangle route trying to minimize impact to ATC.

Rick