Which instrument senses the rate of change in static pressure that results from a change in aircraft altitude?

• A. Altimeter
• B. Attitude indicator
• C. Rate of climb indicator
• D. Airspeed indicator

Answer: (C)

The rate at which altitude changes is reflected by how quickly static pressure is changing, and the instrument that responds to that change is the vertical speed indicator (rate of climb indicator). It is connected to the static pressure system and uses a diaphragm to sense the rate of pressure change. As you climb, static pressure drops; the faster the altitude is changing, the more quickly the pressure changes, producing a deflection that shows climb or descent in feet per minute. The other instruments don’t measure this rate of change: the altimeter uses static pressure to display altitude itself, not how fast that altitude is changing; the attitude indicator uses gyroscopic sensing to show aircraft orientation, not pressure; and the airspeed indicator uses the difference between pitot (dynamic pressure) and static pressure to show airspeed, not the rate of altitude change.