Which instrument uses static pressure only to indicate altitude?

• A. Airspeed Indicator
• B. Turn Coordinator
• C. Altimeter
• D. Attitude Indicator

Answer: (C)

Altitude is determined by sensing ambient static pressure with a sealed mechanism that expands or contracts as pressure changes. The altimeter converts that static pressure into a readout of elevation, calibrated to a standard atmosphere and adjusted with the altimeter setting to reflect local sea-level pressure. Because it relies only on static pressure, it directly indicates altitude. Other instruments use different principles: the airspeed indicator compares dynamic pressure from the pitot tube with static pressure to show speed, while the turn coordinator and attitude indicator use gyroscopes to indicate turn rate and aircraft orientation, not pressure-derived altitude. Make sure the altimeter setting is correct for accurate altitude readings, since changing weather can alter local pressure.