Flight level is defined relative to which standard pressure setting?

Flight level is defined relative to which standard pressure setting?

• A. 29.92 inHg
• B. 1010 hPa
• C. 1000 hPa
• D. 1013.25 hPa

Answer: (D)

Flight levels are defined using a fixed reference pressure known as the standard atmosphere at sea level. That reference pressure is 1013.25 hPa (29.92 inHg). When the altimeter is set to this standard pressure, the readout corresponds to pressure altitude, not local elevation, so flight levels remain consistent worldwide regardless of surface pressure changes. The inches of mercury value is simply the same pressure expressed in different units, but the standard pressure used for defining flight levels is 1013.25 hPa.

Flight levels are defined using a fixed reference pressure known as the standard atmosphere at sea level. That reference pressure is 1013.25 hPa (29.92 inHg). When the altimeter is set to this standard pressure, the readout corresponds to pressure altitude, not local elevation, so flight levels remain consistent worldwide regardless of surface pressure changes. The inches of mercury value is simply the same pressure expressed in different units, but the standard pressure used for defining flight levels is 1013.25 hPa.