Very few aircraft are capable of sustained flight at 60,000 feet, an altitude known as the "near-space" region. The most famous example is the Lockheed U-2 "Dragon Lady" reconnaissance aircraft, which can fly at altitudes exceeding 70,000 feet. NASA also operates the WB-57, a highly modified bomber used for atmospheric research, which routinely flies above 60,000 feet. In the realm of business jets, the Bombardier Global 8000 and the Gulfstream G700 are certified to fly as high as 51,000 feet, which is significantly higher than commercial airliners (which typically cruise between 30,000 and 42,000 feet) but still well below the 60,000-foot mark. Historically, the Concorde was the only commercial passenger jet to regularly cruise at 60,000 feet. Beyond manned aircraft, high-altitude long-endurance (HALE) drones like the RQ-4 Global Hawk and certain specialized weather balloons are the primary occupants of this extreme atmospheric layer.