This information was received from DFS - the German Air Navigation Service Provider

• An Occurrence with a military fighter aircraft busting a level has drawn our attention to a possible deficiency with procedures associated with level bust incidents.
• The question is: What is to be expected from pilots busting a level by more than 1000ft, when, depending on the position of other traffic, immediate return to the cleared level could be more dangerous than busting the level itself?
• The situation is especially dangerous with high performance aircraft on busy ATC frequencies, where perhaps a pilot suddenly recognizes his error and does not delay his return back to cleared level until he is able to confirm it with ATC. Level bust by high performance aircraft, like military fighters, can be easily greater than 1000ft in a very short time, where the controller is not able to detect this level bust in a timely manner.