FAA Ground School Practice Test

At what altitude shall the altimeter be set to 29.92, when climbing to cruising flight level?

1. 10,000 feet MSL

2. 12,000 feet MSL

3. 18,000 feet MSL

4. 25,000 feet MSL

The correct answer is: 18,000 feet MSL

The correct answer is 18,000 feet MSL because this is the altitude at which pilots transition from using altimeter settings based on local station pressure to a standard altimeter setting of 29.92 inches of mercury (inHg). This altitude marks the beginning of the flight levels, where altitude is reported in "flight levels" instead of feet above mean sea level (MSL). When an aircraft climbs to 18,000 feet, it is essential to set the altimeter to the standard pressure of 29.92 inHg to ensure uniformity in altitude reporting amongst all aircraft. This standardization is critical for maintaining safe vertical separation between aircraft, especially in controlled airspace where many planes are operating at the same time. Options emphasizing altitudes such as 10,000, 12,000, or 25,000 feet do not represent the transition point to standard pressure, as they fall below or are not the specifically designated point for this procedure. Therefore, setting the altimeter to 29.92 at 18,000 feet is a standardized practice critical for ensuring safety and efficiency in the airspace system.