Then we got the standard safety lecture—what to do in an emergency, like if the galley runs out of Bloody Mary mix—then we were rolling, and then we were climbing out. On my seatback screen I saw the ground drop away behind us, becoming a detailed scale model, then a contour map. Speed and angle of climb seemed—in my limited experience, at least—pretty extreme. But then the SCRAMjets kicked in—the pilot actually warned us before he lit them off—and I got a taste of what "fast" and "steep" really mean. Some ridiculously short time later, a voice came over the intercom, telling us we were at cruising altitude—23,000 meters, give or take—and flying at a mind-buggering 29,000 klicks per hour.