What is pressure altitude?

Pressure altitude is defined as the altitude indicated by the altimeter when it is set to the standard barometric pressure of 29.92 inches of mercury (Hg). This standard setting allows pilots to gauge altitude in a way that is independent of local weather variations. By using this standardized measurement, pilots can ensure consistency in altitude reporting, which is critical for safe navigation and separation from other aircraft.

This definition aligns with the principles of atmospheric pressure and how it affects altimeter readings. When an aircraft's altimeter is correctly adjusted to 29.92 inches of mercury, it provides a reference point for the pressure in relation to sea level. Understanding pressure altitude is essential for various flight operations, including performance calculations and ensuring compliance with air traffic control altitude assignments.

The other definitions do not accurately match the term "pressure altitude." The altitude at which the aircraft is flying refers to its actual flying altitude, which may vary based on local atmospheric conditions. The vertical distance above ground level (AGL) measures how high the aircraft is above the terrain directly beneath it, which is different from pressure altitude. Lastly, the vertical distance above sea level refers to altitude as measured from sea level, but it does not account for the pressure adjustments made to standardize altitude across