What is the standard altimeter setting for altimeter readings in the USA?

The standard altimeter setting for altimeter readings in the USA is 29.92 inches of mercury at sea level. This figure is crucial as it represents the reference pressure used for flight operations, enabling aircraft altimeters to display altitude accurately. The choice of 29.92 inches is established by the International Standard Atmosphere (ISA), which provides a consistent basis for aviation and meteorological measurements across the globe.

Using this standard setting allows pilots to maintain a uniform altitude, ensuring safe vertical separation from other aircraft and the terrain. When altimeters are set to this value, they can show true altitude relative to sea level in a standardized manner. It’s essential for pilots to align their altimeter settings with this standard to avoid discrepancies in altitude readings during flight operations.

The other values listed do not represent the standard altimeter setting; they may reflect local pressure readings at specific airports or during certain weather conditions, but they do not serve as the universal standard for altimeter calibration in aviation across the United States.