What pressures affect the pitot-static system?

• A. Dynamic and static
• B. Total pressure and static pressure
• C. Dynamic pressure only
• D. Total pressure only

Answer: (A)

A pitot-static system works with two pressure sources: the pitot tube gives total (impact) pressure while the static port provides the ambient static pressure. The instrument that indicates airspeed is driven by dynamic pressure, which is the difference between total pressure and static pressure (q = Pt − Ps). The static pressure serves as the reference for altitude and pressure changes, while the dynamic pressure changes with airspeed and is what the airspeed indicator interprets. Therefore, the pressures that directly affect the pitot-static readings are the dynamic pressure and the static pressure. Total pressure is part of the relationship (Pt equals Ps plus q), but the indication hinges on the difference between Pt and Ps, i.e., the dynamic pressure, with Ps setting the reference.