Funky ground speed

[Minus Tran]

Hi,

this is my first post to this forum and I hope I've chosen the right forum section. And this has probably come up already
but I couldn't find it in the forum so...

So I'm looking at this plane: LZ-EAB

and it is showing the funkiest ground speed. The speed graph shows ground speeds at cruising altitude between
544 km/h and 1337 km/h. And other A320s I have been staring at in the past, don't show such speed variation like
this one. So this is probably some strange measurement artifact or so.

In any case, I'd be very interested to hear what the real reason is, if anyone has an idea.

Thx!

[Oblivian]

Someone is feeding faulty data, or it's GPS unit has a fault.

It's reporting massive altitude and airspeed changes. This effects ground speed as it's calculated from those

https://en.wikipedia.org/wiki/Ground_speed