What is indicated altitude?

Indicated altitude refers to the altitude that is read directly from the altimeter instrument of an aircraft. This reading is based on the current atmospheric pressure and is not corrected for any variations in temperature or pressure from standard values. Essentially, it reflects how high the aircraft is flying above sea level based on the local air pressure, as measured by the altimeter.

When flying, pilots use indicated altitude for navigation and to maintain safe flight levels but must be cautious since it may not always accurately represent the aircraft's true altitude due to atmospheric conditions. This is why other altitudes like true altitude (which is above sea level) and pressure altitude (adjusted to standard pressure) are also important for pilots to understand and use in conjunction with indicated altitude for safe flight operations.