What should the altimeter be set to when in flight within the altimeter setting region?

When flying within the altimeter setting region, the altimeter should be set to the current pressure setting for the nearest weather station. This practice is critical to ensure accurate altitude readings, which are essential for safe flight operations.

The reason for using the current setting from a nearby station is that atmospheric pressure can vary significantly over small distances and changes with weather systems. By setting the altimeter to the latest information available from a nearby station, pilots can heighten their situational awareness and ensure that their altitude measurements align with the actual cloud bases, terrain elevations, and air traffic operations in the area.

Using the last altimeter setting or an average setting does not provide the most accurate or up-to-date information, as weather conditions can change rapidly, affecting pressure. Setting the altimeter to standard pressure is generally only done above the transition altitude and not within the altimeter setting region, where local conditions are more relevant for accurate altitude reporting.