1.3 ICAO Standard Atmosphere

International Civil Aviation Organization (ICAO) have accepted and adopted the following standard atmospheric condition for the aviation metrology.

Following are the set standard atmosphere of ICAO:

• The air is a dry gas

• Mean sea level pressure is 29.92 inches of mercury

• Mean sea level temperature is 15 ⁰C

• The temperature decreasing rate with height is 1.98 ⁰C per 1000 feet