What does pressure altitude (PA) refer to?

Pressure altitude (PA) is defined as the altitude indicated when the altimeter is set to the International Standard Atmosphere (ISA) standard setting of 29.92 inHg (1013.25 hPa). This measurement is crucial for various flight operations and calculations, particularly when determining aircraft performance and planning, as pressure altitude correlates with the pressure in the atmosphere at a given altitude.

When the altimeter is set to this standard reference pressure, it provides a consistent method to report altitude, ensuring that pilots can effectively communicate and understand their altitude with respect to a standardized atmospheric model. This is particularly important for tasks like cruise flight, navigation, and altitude assignments in controlled airspace.

The other options do not correctly describe pressure altitude: it is not adjusted for wind conditions, it does not measure actual height above ground level, and it certainly remains relevant in modern navigation, especially with the critical nature of altitude awareness in aviation safety.