What happens to the stall speed at high altitude as you climb?

As an aircraft climbs to higher altitudes, the stall speed increases. This is primarily due to the reduction in air density with altitude. Air density decreases as altitude increases, which impacts the lift produced by the wings and subsequently influences the stall speed. The stall speed is defined as the minimum airspeed at which the aircraft can maintain level flight without stalling, and it is directly related to the aircraft's weight and the lift generated by its wings.

As air density decreases, the wings must generate more lift to maintain the same amount of total lift required to keep the aircraft flying. Since lift is a function of both airspeed and air density, a decrease in air density necessitates a higher speed to produce the required lift. Therefore, as the altitude increases and air density decreases, the stall speed must increase to ensure that the aircraft can maintain efficient flight without entering a stall condition.