What is 'stall speed' in aviation?

Stall speed in aviation refers to the minimum airspeed at which an aircraft can maintain controlled flight. When an aircraft flies below this speed, the lift generated by the wings becomes insufficient to counteract the weight of the aircraft, leading to a stall condition. At stall speed, the aircraft is on the brink of losing lift, making the speed critical for safe maneuvering, particularly during takeoff and landing phases. Understanding stall speed is essential for pilots to ensure they do not inadvertently enter a stall while maneuvering, especially in situations requiring sharp turns or climbs.

The other options describe different concepts related to aircraft performance but do not accurately define stall speed. For instance, the maximum speed for controlled ascent focuses on climbing performance rather than the threshold for maintaining controlled flight. The speed at which an aircraft lands safely is related to landing speed, which typically varies from stall speed depending on the aircraft's configuration during landing. The speed that exceeds structural limits refers to overspeed conditions that can cause aircraft damage, which is unrelated to stall speed.