Some interesting facts about the Cessna Citation X private jet: It isn't just the fastest private jet in history, it’s also a machine with proven supersonic capability. Rumor has it that Cessna’s Wichita plant includes a “Mach Conference Room,” a quiet nod to what test pilots already know: to certify a max speed of Mach 0.935, FAA rules required dive tests at least 0.07 Mach faster. And during those flights, the X repeatedly slipped beyond Mach 1 in high-altitude restricted airspace. Several pil