If I may quote Rhymenoceros to get this back to a nuts and bolts discussion ...
Bottom line: a smooth pull into a loop from 100ft was not a violation of his DA and should not have been a risk to its safe execution had the aircraft had enough energy to complete the manoeuvre by at least 500ft AGL.
The pilot at the controls has to make that assessment on time and on task if the decision to initiate (for whatever reason) was to begin at 100'. (And for planning ahead, build some energy, eh?) Was it rehearsed that way? "Practice the way you are going to play!" Was that adage complied with?
Airshow aerobatics should be flown with necessary margin ie. a looping manoeuvre should not be flown by ‘max performing’ the aircraft. Instead the aircraft should have excess energy in which the pull can be somewhat relaxed, allowing for increased altitude over the top (gate) and thus ample margin on the way back down. These techniques are not ‘taught’ during military flying training or if one was doing competition aerobatics. It is specific to the safe execution of display flying where one is looking to show off the aircraft in an attractive manor. {sic} Not displaying ones skill for executing the manouevures or the full capabilities of the aircraft.
This goes into the planning of the event and of the maneuver, as well as the execution.
@legalapproach: thanks, great post.