As LHRT stated, the 'Cloudbreak Procedure' originated with the military but you have to bear in mind that its a bit different getting to the bottom (700'agl) not visual and using your inertia to grab altitude and then ejecting!! PC12s unfortunately don't have that option.
The CB Procedure, although a lot of fun and a real test of a pilot's raw ability, was generally regarded by most pilots (in the RFDS section I worked for) as a poor second option to gliding from altitude to overhead the field then high key, low key, final all the way to the threshold. Personally who cares if it takes 20 min to finally hit the ground?
On a side note I always wondered if it was possible for GPS manafacturers to design a standard High key, Low key, Final overlay for application on any (1000m or more) aerodrome in your GPS's database. Surely it would be simple trigonometry using the aerodrome reference point?
cheers
Sarcs
ps have over 1500hrs in the PC12 but I would always prefer to have my backside parked in the trusty old B200. The pucker factor is not quite so great when flogging around in the middle of the night over tiger country!