How should an altimeter be adjusted for variations in atmospheric pressure?

The correct answer is based on the principle that altimeters are calibrated to a standard pressure setting, which is 29.92 inches of mercury (inHg) or 1013.25 hPa. In aviation, altimeters measure aircraft altitude by comparing the atmospheric pressure with this standard pressure. When the atmospheric pressure changes due to weather conditions, pilots must adjust the altimeter to reflect the current local pressure.

Setting the altimeter to the standard setting ensures that everyone is using a uniform reference point, allowing for consistent altitude readings across different aircraft. This adjustment is crucial when flying or when making altitude decisions, particularly in situations where pressure can vary significantly, such as during weather changes.

The other options do not directly relate to the proper adjustment of an altimeter for atmospheric pressure variations. Using regional standard settings does help in some situations, but does not focus on the standard pressure reference. Aircraft weight does not impact altimeter readings, nor does local time zones have any connection to atmospheric pressure measurements or the use of an altimeter.