Indicated altitude is defined as:

Indicated altitude is accurately described as the altitude that an aircraft's altimeter displays when it is set to standard atmospheric pressure, which is 29.92 inches of mercury or 1013.25 hPa. Under standard atmospheric conditions, this reading provides a consistent reference for altitude that pilots can rely on, especially in controlled airspace.

It's crucial to set the altimeter correctly for accurate readings, as changes in atmospheric pressure can affect the altimeter's indication. The indicated altitude is primarily used during flight operations for maintaining flight levels and ensuring safe separation from other aircraft and terrain.

Understanding indicated altitude is fundamental for pilots to navigate and communicate altitude information accurately, especially in environments where air traffic control requires precise altitude information for airspace management.