Reference RAT 5's question about height planning to exit a loop the answer is that it depends since there are a number of variables: entry speed, G on pull up (and pull out), rotational (or autorotational) components within the figure, aircraft performance, density altitude and target exit speed. You may plan to exit at your point of entry, gain height or lose it depending upon your sequence.
All display pilots will have gate heights and, where appropriate, speeds for the key components of their sequences. An individual's display authorisation will stipulate a minimum height for aerobatic figures and fly-by, but it is up to the pilot to set their own limits above these minima for the particular display they are flying. This is particularly relevant where someone has a DA for multiple types, since a single authorisation applies across all categories on your DA. To illustrate the point, you may have an aerobatic piston DA covering everything from a Jungmeister to a P51 Mustang and your base height (for aerobatics and fly past) across all types will be the same. Obviously a loop radius in P51 is much larger than a Jungmeister so the margin of error in feet is significantly greater. One would, or should, adjust one's own personal hard deck accordingly.
Ref: phiggsbroadband, you are correct that strictly a "loop" enters and exits on the same axis. There are many figure variants with loop segments and lines or rolls that change the shape and/ or axis of the figure. It is hard from the video I have seen to ascertain whether the figure flown was a clover or a reverse half cuban but the aerobatic taxonomy is irrelevent in the context of this tragedy. The key risk issue is pulling through the vertical (the reason that a reverse half cuban is a significantly higher risk figure low level than a half cuban).
A few additional points worth making:
- We live in a world where instant answers to everything tend to be demanded, but speculation until the AAIB has completed its investigation is distressing for those involved and completely unproductive.
- There is no complacency within the display flying community or the bodies that regulate us regarding the risks inherent in staging a flying display. On the whole the safety record has been extremely good over the years compared with other higher risk pursuits (such as eventing and motor sports), largely thanks to the professionalism of all involve. Procedures were revised, for example, a couple of years ago for the granting of higher level aerobatic DAs when a relatively inexperienced aerobatic pilot creashed after an unssucessful recovery from a Mulleroid.
- That said, it is unthinkable in my view that the scale of this tragedy will not have an effect on the way things are done in the future. My hope is that everyone involved retains a sense of objectivity and that ultimately the baby isn't thrown out with the bathwater.
My thoughts are with all of the families that have had to deal with the terrible consequences of this weekend's events.