What is the standard reference atmospheric pressure used to determine Flight Levels?

What is the standard reference atmospheric pressure used to determine Flight Levels?

• A. 29.92 inches of mercury
• B. 30.00 inches of mercury
• C. 29.92 kilopascals
• D. 29.29 inches of mercury

Answer: (A)

Flight levels are defined using a fixed reference pressure so every airplane shares the same vertical reference, regardless of local weather pressure. That standard pressure is 29.92 inches of mercury, which corresponds to about 1013.25 hPa. When flying above the transition altitude, pilots set the altimeter to this standard pressure, and the altitude readout is expressed as a flight level (for example, FL180). The other options aren’t correct because they either use the wrong value or the wrong units (kilopascals) for the standard reference pressure.

Flight levels are defined using a fixed reference pressure so every airplane shares the same vertical reference, regardless of local weather pressure. That standard pressure is 29.92 inches of mercury, which corresponds to about 1013.25 hPa. When flying above the transition altitude, pilots set the altimeter to this standard pressure, and the altitude readout is expressed as a flight level (for example, FL180). The other options aren’t correct because they either use the wrong value or the wrong units (kilopascals) for the standard reference pressure.