How is pressure altitude calculated?

The calculation of pressure altitude involves adjusting the indicated altitude based on the standard atmospheric pressure reference, which is 29.92 inches of mercury (inHg). When you set your altimeter to this standard pressure setting, the altitude displayed is your pressure altitude. This is a critical step when assessing aircraft performance and ensuring proper separation from other aircraft, especially in high-altitude flight operations.

By using the relationship expressed in the chosen answer, which indicates that pressure altitude can also be calculated by taking the standard atmospheric pressure (29.92 inHg) and subtracting the current altimeter setting, you arrive at a value that reflects altitude above a theoretical standard model of the atmosphere. The formula itself effectively allows you to convert your local altimeter setting into the standard pressure reference, thus determining how high you are flying relative to sea level in terms of pressure.

The other options do not accurately reflect the method of calculating pressure altitude. Simply reading the indicated altitude at a certain altimeter setting or relying on field elevation does not take into account the standard atmospheric reference needed for pressure altitude. Adjustments for weight also do not relate to altitude measurement; thus, they are not relevant in this context.