FAA Military Competency Practice Exam

What altimeter setting is required when operating an aircraft at 18,000 feet MSL?

1. 30.00" Hg

2. 29.92" Hg

3. 28.50" Hg

4. 31.00" Hg

The correct answer is: 29.92" Hg

When operating an aircraft at 18,000 feet Mean Sea Level (MSL), the correct altimeter setting is 29.92 inches of mercury (Hg). This altitude is significant because it marks the transition point from the use of local altimeter settings, typically based on barometric pressure readings at sea level, to a standardized setting for all aircraft flying above 18,000 feet. This transition level is established to ensure that all aircraft maintain a consistent reference, reducing the risk of altitude-related discrepancies that could lead to in-flight accidents, especially in congested airspace. The setting of 29.92" Hg is known as the standard pressure setting, and all pilots operating above this altitude are required to use it for their altimeters. Utilizing a consistent pressure setting allows for maintaining standardization among various aircraft and ensures safe vertical separation between them. Therefore, when flying at or above this altitude, setting the altimeter to 29.92 inches of mercury is essential for accurate altitude readings and safe operation.