Yes! SIMPLE! But they did NOT and crashed (unless altimeter mistake and other founding of the Enquiry).
WHY? HOW?
Well for starters the American charts don't appear to have a distance/altitude profile of the type displayed on the Adelaide chart, so unless they made up their own profile they did not have anything to get on and stay on.
I'm not really sure what is confusing about the grey zones, they are areas you are not permitted to fly. As far as being taught about the 15%, I must say I didn't know about it, but I don't need to know about it as my approach descents are all somewhere around 5%. In fact the descent rate required to break 15% would have to be up over 2000 fpm so I don't see that it is relevant.