Helicopter PPL Checkride Practice Test

The airspeed indicator is the correct answer because it relies on the Pitot Static system to function accurately. The Pitot Static system uses both the dynamic pressure from the Pitot tube, which faces into the relative wind, and static pressure from the static port. The difference between the two pressures allows the instrument to measure the aircraft's airspeed.

This system is vital for providing crucial data for pilots, as airspeed is a key indicator for maintaining safe flying conditions, particularly during takeoff and landing phases. The other instruments mentioned, such as the heading indicator, turn coordinator, and attitude indicator, do not use the Pitot Static system for their operation. Instead, they are dependent on other sources for their readings; for example, the heading indicator generally uses magnetic compasses and gyroscopic principles, while the turn coordinator relies primarily on the aircraft's bank angle to indicate the rate of turn. The attitude indicator uses gyroscopes to display the aircraft's orientation relative to the horizon.