What are the standard temperature and pressure values for sea level?

• A. 15°C and 29.92 inHg
• B. 0°C and 29.92 inHg
• C. 15°C and 30.50 inHg
• D. 20°C and 29.92 inHg

Answer: (A)

Standard sea-level conditions are defined as a temperature of 15°C and a pressure of 29.92 inches of mercury. This pairing is the reference point used in aviation to calibrate instruments like the altimeter and to base performance calculations, because it defines the International Standard Atmosphere at sea level. While actual sea-level temperatures vary, 15°C is the agreed standard, and 29.92 inHg corresponds to about 1013.25 hPa. The other options don’t fit because 0°C or 20°C are not the standard sea-level temperature, and 30.50 inHg would be a higher pressure than the standard sea-level value.