Which group of instruments uses static pressure?

• A. Altimeter, Vertical Speed Indicator, and Airspeed Indicator
• B. Altimeter and VSI
• C. Airspeed Indicator only
• D. VSI and Altimeter only

Answer: (A)

Static pressure serves as the reference pressure for several cockpit instruments, and understanding how each uses it helps explain why all three instruments in this group rely on it.

The altimeter directly measures ambient static pressure from the aircraft’s static port, and its calibrated scale converts that pressure into an altitude reading. As you climb or descend, the static pressure changes, and the altimeter shows the corresponding altitude.

The vertical speed indicator also uses static pressure, but in a dynamic way. It tracks the rate of change of static pressure over time. A small change in static pressure over a short period causes the VSI to deflect, indicating climb or descent rate.

The airspeed indicator relies on two pressures: the dynamic pressure from the Pitot tube (total pressure) and the static pressure from the static port. The difference between those pressures is displayed as indicated airspeed. While dynamic pressure drives the measurement, static pressure is still essential as the reference pressure in this calculation.

Since all three instruments depend on static pressure in some form, this group is the correct one.