Which instrument uses static pressure from the pitot-static system to indicate rate of climb or descent?

Which instrument uses static pressure from the pitot-static system to indicate rate of climb or descent?

• A. Airspeed indicator
• B. Altimeter
• C. Vertical speed indicator
• D. Attitude indicator

Answer: (C)

The key idea is that this instrument responds to how fast the ambient static pressure changes, not to the absolute pressure itself. It’s connected to the static pressure from the pitot-static system, and a connected diaphragm or capsule measures the rate of change of that pressure. As you climb, the surrounding air pressure falls, and the static pressure changes at a certain rate which the instrument converts into a vertical speed reading (feet per minute). As you descend, the static pressure rises, and the instrument shows a descent rate. Because it relies on the rate of change rather than steady pressure, it indicates how quickly you’re climbing or descending, not your current altitude. This is distinct from the airspeed indicator, which uses pitot (dynamic) pressure and static pressure to show speed; the altimeter uses static pressure to display altitude; and the attitude indicator is gyro-driven rather than pressure-driven. The vertical speed indicator can lag during rapid pressure changes and can be influenced by static-system blockages, but its purpose and operation are to translate the rate of change in static pressure into climb or descent rate.

The key idea is that this instrument responds to how fast the ambient static pressure changes, not to the absolute pressure itself. It’s connected to the static pressure from the pitot-static system, and a connected diaphragm or capsule measures the rate of change of that pressure. As you climb, the surrounding air pressure falls, and the static pressure changes at a certain rate which the instrument converts into a vertical speed reading (feet per minute). As you descend, the static pressure rises, and the instrument shows a descent rate. Because it relies on the rate of change rather than steady pressure, it indicates how quickly you’re climbing or descending, not your current altitude.

This is distinct from the airspeed indicator, which uses pitot (dynamic) pressure and static pressure to show speed; the altimeter uses static pressure to display altitude; and the attitude indicator is gyro-driven rather than pressure-driven. The vertical speed indicator can lag during rapid pressure changes and can be influenced by static-system blockages, but its purpose and operation are to translate the rate of change in static pressure into climb or descent rate.