Which of the following defines pressure altitude?

Pressure altitude is defined as the altitude indicated by the altimeter when it is set to the standard atmospheric pressure, which is 29.92 inches of mercury (inHg). This measurement is crucial in aviation because it provides a standardized reference point for altitude that allows for consistent communication and calculations among pilots, regardless of local atmospheric pressure variations.

When the altimeter is set to 29.92 inHg, it effectively normalizes the atmospheric pressure to a standard level, allowing for a common reference that is essential for maintaining safe separation between aircraft and accurate altitude reporting. Pressure altitude is particularly important during flight planning and altitude selection, as it helps pilots understand their aircraft's performance under varying atmospheric conditions.

Understanding pressure altitude is essential in various scenarios, such as calculating density altitude and ensuring that altitude restrictions and airspace boundaries are adhered to, which helps maintain safety in the skies. Other options provided do not accurately capture this definition.