What does "AIRSPEED" mean?

Airspeed refers to the speed of the aircraft in relation to the surrounding air, which is crucial for understanding aircraft performance and control. This measurement is essential for pilots, as it affects lift, drag, and overall aircraft handling.

When flying, the surrounding air plays a direct role in how the aircraft interacts with that air mass, determining how effectively it can generate lift and maneuver. The concept of airspeed helps pilots assess various flight conditions, including stall speeds, climb rates, and approach and landing speeds.

While the speed of the aircraft relative to the ground is a different concept known as groundspeed, that measurement does not take into account wind effects and can sometimes be misleading concerning performance. The other options provided do not encapsulate the comprehensive definition of airspeed. For instance, takeoff speed is a specific condition rather than a general measurement of airspeed, and the altimeter measures altitude, not airspeed. Therefore, the definition that aligns with the true meaning of airspeed is its relationship to the surrounding air.