What does an altimeter reading of 1,850 ft MSL indicate when set to 30.18?

An altimeter reading of 1,850 feet MSL (Mean Sea Level) indicates the height above sea level based on the pressure setting of the altimeter. When the altimeter is set to 30.18 inches of mercury (Hg), this is the standard sea level pressure, meaning that the altimeter is currently calibrated to a reference pressure that is acceptable for determining altitude in standard atmospheric conditions.

To arrive at the indicated altitude, you must understand the relationship between the altimeter setting and the actual pressure at the location where the reading is taken. If the actual local pressure is below the standard setting (30.00 inHg), the altimeter will read higher than the true altitude. Conversely, if the local pressure is higher, the altitude would read lower.

In this case, setting the altimeter to 30.18 and reading an altitude of 1,850 feet suggests that the actual pressure at that location is lower than the set pressure. Because the altimeter is set to a higher pressure than the actual conditions, it shows an altitude that is lower than it would if the local pressure were equal to the altimeter's setting or if it were lower than 30.18 inches of mercury.

Thus, the reading of 1