Definition
Pressure Altitude is the altitude indicated when the altimeter's barometric setting is adjusted to the standard sea-level pressure of 29.92 inches of mercury (1013.2 hPa). It represents the height above the standard datum plane and is used as the reference for performance calculations and for flight at and above 18,000 feet MSL in the United States.
Plain English
It's the altitude your altimeter shows when you set it to a fixed standard pressure value (29.92) instead of the local pressure. It gives every aircraft a common reference, so performance charts and high-altitude flights all use the same yardstick.
Context Anchor
Seen in density altitude, aircraft performance, and altimeter-setting discussions.
Derivation
From Latin pressura (pressing) and altitudo (height). The term reflects that this altitude is derived from a pressure reference rather than from physical height above terrain or sea level.
Why Pilots Care
It provides the consistent reference needed to calculate true aircraft performance and takeoff or landing distances.
Grounding Statement
If you set the altimeter to 29.92, the altitude it shows is pressure altitude.
Intuition Check
Pressure altitude does not mean your exact height above the airport or your exact height above sea level. It means altitude measured from a standard pressure reference.
Example Sentence 1
Before calculating takeoff performance, the pilot set 29.92 in the altimeter window and noted a pressure altitude of 1,500 feet.
Example Sentence 2
With a pressure altitude of 4,000 feet and high temperature, the pilot determined the runway distance needed for takeoff.