To try to imagine a test pilot landing for certification consider that a Gulfstream 550 can be flying at 110 knots at 50 feet above the runway. Measuring from that point the pilot can touchdown and stop in a total distance of less than 2,300 feet. And that would be at a landing weight of about 50,000 pounds. The Gulfstream is an amazing airplane with exceptionally good brakes and large spoilers that automatically deploy on touchdown, but that is an incredibly short landing. Gulfstream pilots are good, but I don't think many would find a 3,000-foot runway satisfactory, even though the book says it offers a 30 percent cushion over what the book says it required. Adding 15 percent to the required runway of a Gulfstream, in this example, is no big deal. But, if the airplane is being flown for hire, the required runway length in the manual must be no longer than 60 percent of the available runway. Now, add another 15 percent to that, and land at a higher weight, and the number of runways available can become restrictive.