The aircraft is over flying an aerodrome at 600 feet above mean sea level (AMSL), but its indicated altitude is 1500 feet. To find the height above the aerodrome, subtract the difference between the indicated altitude the aerodrome's elevation:

• 1500 ft (indicated altitude) - 600 ft (AMSL) = 900 feet.

Height: This refers to the measurement above ground level, typically indicating the height above an aerodrome. Specifically, it is the height above the aerodrome reference point when the QFE setting is used on the sub-scale.

Altitude: This represents the measurement above mean sea level. When the QNH setting is used on the sub-scale, the altimeter shows altitude.