Certified Flight Instructor - Flight Instructor Airplane Practice Exam

In aviation terms, what is the standard measure of altitude indicated by an altimeter?

1. Feet above ground level

2. Feet above sea level

3. Pressure altitude

The correct answer is: Feet above sea level

The correct answer is feet above sea level. Altimeters in aviation are primarily calibrated to measure altitude in reference to the mean sea level (MSL). This is crucial for ensuring standardization in altitude reporting and enhances safety by allowing pilots and air traffic control to maintain separation between aircraft. When pilots read their altimeters, they are receiving information on the aircraft's height relative to the average surface level of the ocean, rather than its height above the ground or terrain, which can vary significantly depending on the geographic location. The other options, such as feet above ground level, pertain to the altitude relative to the underlying terrain, which can change as the aircraft flies over varying elevations. Pressure altitude refers to the altitude indicated when the altimeter is set to the standard atmospheric pressure of 29.92 inches of mercury, but it does not provide a direct reference to sea level unless adjusted. Therefore, feet above sea level remains the most widely accepted and utilized measure of altitude in aviation.