AFOQT Practice Test

What happens to the stall speed of an aircraft as it gains altitude?

1. The stall speed decreases

2. The stall speed remains constant

3. The stall speed increases

4. The stall speed is irrelevant to altitude

The correct answer is: The stall speed increases

As an aircraft gains altitude, the stall speed increases due to the reduction of air density and the dynamic pressure acting on the wings. Stall speed is defined as the minimum speed at which an aircraft can maintain straight and level flight before it loses lift. This minimum speed is influenced by the characteristics of the aircraft and the properties of the air in which it is flying. At higher altitudes, the air becomes less dense. Lift is generated by the wings above a certain critical angle of attack, which is dependent on the airspeed and the density of the air. As the aircraft climbs, the lower air density means that for a given angle of attack, the wings experience less lift compared to lower altitudes. To maintain the same amount of lift, the aircraft must fly at a higher speed, which results in an increase in stall speed. This relationship highlights the crucial importance of understanding how altitude affects flight dynamics, especially for pilots who must make adjustments to their flying techniques at different altitudes to ensure safety and performance.