Which instrument uses static pressure readings to determine altitude most directly?

• A. Airspeed Indicator
• B. Vertical Speed Indicator
• C. Altimeter
• D. Attitude Indicator

Answer: (C)

Altitude is determined by how ambient static pressure changes with height. The instrument that directly translates those static-pressure changes into an altitude reading is the altimeter. Inside it, sealed aneroid capsules respond to the surrounding static pressure: as you climb and the pressure drops, the capsules expand or contract, moving the instrument hands to display altitude. The altimeter is calibrated to show altitude above mean sea level and is adjusted with the local pressure setting so the reading matches your actual height above the reference surface.

In contrast, the airspeed indicator uses dynamic pressure (the difference between pitot pressure and static pressure) to measure how fast you’re moving through the air, not your height. The vertical speed indicator relies on how quickly static pressure changes to show climb or descent rate, rather than a direct altitude reading. The attitude indicator uses a gyroscope to show orientation and is not dependent on pressure readings.