What is the lowest usable flight level for pressures between 29.91 and 29.82?

What is the lowest usable flight level for pressures between 29.91 and 29.82?

• A. FL180
• B. FL190
• C. FL200
• D. FL210

Answer: (B)

The lowest usable flight level for pressures between 29.91 inches of mercury and 29.82 inches of mercury is FL190. This is determined by the International Civil Aviation Organization (ICAO) standards for altimeter setting and flight level determination. In aviation, flight levels are based on standard air pressure settings, which allow for a clear and safe separation between aircraft at different altitudes. When the altimeter setting is above 29.92 inches, the lowest usable flight level typically starts at FL180. However, as the pressure drops below this threshold, the lowest usable flight level changes. For pressures ranging between 29.91 inches and 29.82 inches, the lowest usable flight level is adjusted to FL190 to maintain appropriate terrain and obstacle clearance, especially given that lower pressure could indicate that an aircraft is flying at a higher altitude than what the altimeter indicates. FL190 serves as a buffer altitude, ensuring operational safety for aircraft flying in those atmospheric conditions.

The lowest usable flight level for pressures between 29.91 inches of mercury and 29.82 inches of mercury is FL190. This is determined by the International Civil Aviation Organization (ICAO) standards for altimeter setting and flight level determination.

In aviation, flight levels are based on standard air pressure settings, which allow for a clear and safe separation between aircraft at different altitudes. When the altimeter setting is above 29.92 inches, the lowest usable flight level typically starts at FL180. However, as the pressure drops below this threshold, the lowest usable flight level changes.

For pressures ranging between 29.91 inches and 29.82 inches, the lowest usable flight level is adjusted to FL190 to maintain appropriate terrain and obstacle clearance, especially given that lower pressure could indicate that an aircraft is flying at a higher altitude than what the altimeter indicates. FL190 serves as a buffer altitude, ensuring operational safety for aircraft flying in those atmospheric conditions.