When should the altimeter setting always be adjusted?

The adjustment of the altimeter setting should always be made in the standard pressure region to ensure that altitude readings are accurate relative to standard atmospheric pressure. The standard pressure, defined as 29.92 inches of mercury (Hg), is the reference point for altimeters. When pilots enter an area where the barometric pressure is at standard setting or if they are told to switch to standard pressure by air traffic control, they need to adjust their altimeter to this setting to maintain proper altitude separation from other aircraft and to ensure safety.

Maintaining the correct altimeter setting is crucial for safe vertical navigation. If pilots fail to adjust their altimeter when flying in the standard pressure region, they may misinterpret their altitude, leading to potential altitude conflicts with other aircraft.

While the altimeter adjustments during takeoff, when flying below 5,000 feet, or after crossing airspace boundaries can also be important, they depend on the specific circumstances, such as local air pressure conditions or directives from air traffic control. However, in the standard pressure region, adhering strictly to the standard setting is a fundamental requirement for all pilots.