When adjusting for pressure altitude, what is subtracted from the field elevation?

To adjust for pressure altitude in aviation, the field elevation is corrected by subtracting the altitude value that represents the current atmospheric pressure conditions relative to standard atmospheric conditions.

The correct adjustment to be made reflects differences in pressure, which can affect the indicated altitude and the true altitude of an aircraft. This specific adjustment is based on the expectational standards of atmospheric pressure at sea level (29.92 inHg or 1013.25 hPa).

In this context, subtracting 200 feet from the field elevation would be a typical adjustment that aligns with a pressure setting that is commonly used in flight planning and altitude setting. This adjustment method ensures that pilots are operating within a safe and legal altitude range, taking into account the variance created by non-standard pressure conditions.

Understanding these adjustments is crucial for maintaining safe flight operations and ensuring accurate altitude readings during various phases of flight.