Which altitude is the height above mean sea level?

• A. True altitude
• B. Indicated altitude
• C. Absolute altitude
• D. Pressure altitude

Answer: (A)

Height above mean sea level is true altitude. This is the actual vertical distance between the aircraft and MSL. When you set the altimeter to the local QNH, the instrument reads your height above MSL, but factors like nonstandard temperature can cause the true altitude (your actual height) to differ from the indicated value. Absolute altitude is height above the terrain (AGL), not above MSL; pressure altitude is height above the standard datum plane (29.92 inHg) and is used for flight levels, not for height above mean sea level. Indicated altitude is just what the altimeter shows, which can match or differ from true altitude depending on conditions, but the term specifically describing height above MSL is true altitude.