I am part 91 flying a GV. Of course the loss of pressurzation is most of the time the most restrictive of the possible ETP's. We use Universal to do our international flight planning. We give them them all the info about out trip and our proposed fuel. When we get the flight plan the morning of the trip we just look to see what we would land with if we lost cabin pressure than adjust for winds new leg time and fuel for alternate planning. Universal does a great job and is always more accurate than I would ever be. Hope this helps.