What does the altimeter primarily measure and display?

• A. It measures static pressure and displays altitude as feet above mean sea level.
• B. It measures dynamic pressure to display altitude.
• C. It displays airspeed.
• D. It measures cabin pressure.

Answer: (A)

The altimeter is a sensitive barometer that uses ambient static pressure to determine altitude. As you ascend, the surrounding static pressure decreases, and the instrument’s mechanisms translate that pressure change into an altitude reading, typically shown in feet. It relies on a standard atmosphere model to convert pressure to height. This is different from the airspeed indicator, which uses dynamic pressure to measure speed, and it has nothing to do with cabin pressure. The local barometric setting (the QNH) adjusts the reading so you’re shown as height above mean sea level, aligning the instrument with surface elevations.