Insurance companies and safety experts-self appointed and otherwise-are constantly worrying that owner-flown jets...particularly the coming crop of new light jets, can be flown at 41,000 feet by a single pilot who may not be very experienced. What's up with that? What's so special about 41,000 feet? The answer is that FL 410 is the traditional extreme upper edge of the operating envelope for civilian jets, either airline or business jet. The very first jets were certified to 41,000 feet even though they couldn't get there unless they were virtually out of fuel or carried little payload. While the 707s, DC-8s, Hawker 125s, JetStars and other first and second generation jets ripped along in the high 20s and low 30s, FL 410 loomed over them as a possibility that apparently required on-the-edge airplane performance, and way above average pilot skill to enjoy.