How did "Lady Agnes" (alias Il-62) get there?

On October 23, 1989, an event occurred that still amazes aviation enthusiasts. The Interflug pilot, Heinz-Dieter Kallbach, landed the Il-62 (DDR-SEG) on a grassy field just 868 meters long.
The video capturing this moment still amazes everyone for its "fun" and piloting skill.
For 35 years now, this plane has been a monument commemorating the great events in aviation history.

To answer the question: can a passenger plane land on a rough and uneven grass runway? In East Germany, they managed it but with a Soviet plane.