"Any concerns about a loss of cabin pressurization at those altitudes?"A very relevant question following a post about typical cruise altitudes during ultra long haul flights in the Gulfstream G650.On a flight from Hong Kong to Europe we climb to an initial cruise altitude of 40,100 feet (12,200 meters) as we cross Chinese airspace. Then, as fuel is burned and aircraft weight is reduced, we step climb to 43,000 and 47,000 feet when environmental conditions (Static Air Temperature) permit it. Ok,