What is the role of the pitot-static system and how is airspeed determined?

• A. Pitot measures ambient pressure; static measures total pressure; airspeed is derived from dynamic pressure via calibrated instruments.
• B. Pitot measures total pressure; static measures ambient pressure; airspeed is derived from dynamic pressure (pitot minus static) via calibrated instruments.
• C. Static measures total pressure; airspeed is derived from engine RPM.
• D. Airspeed is determined solely by outside temperature.

Answer: (B)

The pitot-static system provides two essential pressures that let us read airspeed from dynamic pressure. The pitot tube faces into the airstream and measures the stagnation (total) pressure, while the static ports sense the ambient static pressure. The cockpit instrument, the airspeed indicator, is a calibrated device that converts the difference between total pressure and static pressure—dynamic pressure—into an airspeed reading, usually in knots, under standard atmospheric conditions. Temperature and air density affect how that dynamic pressure corresponds to true airspeed, but the method of determination relies on the pressure difference, not on RPM or temperature alone.