Which instrument informs a pilot of airspeed using a pitot tube?

The instrument that informs a pilot of airspeed using a pitot tube is the airspeed indicator. The airspeed indicator functions by measuring the difference between static pressure and dynamic pressure, which is made possible through the pitot tube. The pitot tube is designed to capture airflow as the aircraft moves, allowing it to compute the speed of the aircraft relative to the surrounding air.

The airspeed indicator is critical for ensuring safe flight operations, allowing pilots to maintain airspeeds necessary for different phases of flight such as takeoff, cruising, and landing. Understanding airspeed is essential for managing aircraft performance and for adhering to the aircraft’s operational limits.

In contrast, the vertical velocity indicator measures the rate of ascent or descent of the aircraft, the heading indicator provides information about the aircraft's direction relative to magnetic north, and the gyroscope is used in various instruments, including the attitude indicator, but does not directly measure airspeed. Hence, these other instruments do not utilize the pitot tube to function, making the airspeed indicator the correct choice.