How high can the U-2 aircraft fly? The U-2 aircraft, built of aluminum and limited to subsonic flight, can cruise for many hours above 70,000 feet (21,000 meters) with a payload weighing 3,000 pounds (1,350 kg). Its exact operational specifications are secret.

Very few aircraft are capable of sustained flight at 70,000 feet, an altitude known as "near space" where the air is so thin that the pilot must wear a pressurized spacesuit. The most famous example is the Lockheed U-2 "Dragon Lady," a high-altitude reconnaissance aircraft that has been in service since the Cold War and continues to fly missions in 2026. Another legendary plane is the SR-71 Blackbird, which could fly at over 85,000 feet, though it is now retired. In the modern era, some advanced high-altitude long-endurance (HALE) drones, such as the Northrop Grumman MQ-4C Triton and the RQ-4 Global Hawk, can reach altitudes near or above 60,000–65,000 feet. Commercial airliners typically cruise between 30,000 and 42,000 feet; at 70,000 feet, the aerodynamic and engine requirements are so extreme that only specialized military and research platforms can survive. For a human to fly this high, they are essentially an astronaut, experiencing a deep black sky and the visible curvature of the Earth.