The slowest speed a plane can fly is its stall speed. This is the minimum speed at which the wings can generate enough lift to keep the aircraft airborne. Stall speed varies depending on the aircraft's weight, wing design, and other factors. For example, the Ruppert Archaeopteryx has a certified stall speed of 30–39 kilometers per hour (19–24 mph), while the Vought XF5U can fly as slow as 32 kilometers per hour (20 mph).
It's important to note that aircraft rarely fly near their stall speed. They typically fly much faster, especially during takeoff and landing. However, some aircraft, like the Antonov AN-2, have a very low stall speed and can fly under full control at speeds as slow as 30 mph.
