A barometric altimeter indicates pressure altitude when the barometric scale is set at what value?

The barometric altimeter provides pressure altitude when it is set to 29.92 inches of mercury (Hg). This value represents the standard atmospheric pressure at sea level, which is a baseline for calculating altitude based on air pressure. When the altimeter is adjusted to this specific value, it interprets the ambient atmospheric pressure and relates it to the corresponding altitude above sea level, thereby allowing pilots to maintain a consistent reference for altitude regardless of local weather variations that may change atmospheric pressure.

Using the standard reference of 29.92" Hg ensures that all altimeters are calibrated in a consistent manner, facilitating safer navigation and altitude reporting in aviation. If the altimeter is set to other values, it would not accurately reflect true pressure altitude, which could lead to discrepancies during flight, especially when flying in areas with varying weather conditions.