After leaving the Altimeter Setting Region, what should a pilot set their altimeter to?

After leaving the Altimeter Setting Region, a pilot should set their altimeter to 29.92 inches of mercury, which is considered the standard atmospheric pressure at sea level in the United States under the International Standard Atmosphere (ISA) conditions. This setting is crucial for maintaining consistent altitude readings when operating in a non-towered or less controlled airspace, where local altimeter settings may not be available.

Using the standard pressure allows pilots to accurately report their altitude relative to sea level and ensures uniformity among all aircraft operating at the same altitude, thereby enhancing overall air traffic safety. This practice is particularly important in situations where pilots are transitioning from an area with varying local altimeter settings to cruising flight levels, where a standard reference is necessary for effective vertical separation and collision avoidance.

Setting the altimeter to the current local altimeter setting or the standard pressure of the nearest station is not appropriate once outside the designated altimeter setting region, as those values can fluctuate based on local weather conditions and would not maintain the required altitude reference. Thus, the correct action is to set the altimeter to the standardized pressure of 29.92 inches of mercury.