How is field elevation determined at an airport?

Field elevation at an airport is measured as the height above Mean Sea Level (MSL) at the highest point of any runway. This standard is used because it provides a consistent reference point for aviation operations, ensuring that aircraft can operate safely at the various elevation and terrain levels encountered during takeoff, landing, and taxiing.

Using the highest point of a runway as the reference helps accommodate any variations in elevation across the airport's infrastructure, which is crucial for both air navigation and ground operations. It accounts for factors like topography and local atmospheric pressure variations that might affect aircraft performance.

Other options do not provide an accurate or standardized means of determining field elevation. For instance, referencing from the ground level of the terminal might not represent the elevation of the runways. Similarly, using the mid-point of the runway length could overlook elevation differences at either end, while determining elevation from the lowest point at the airport would not provide a reliable measure for aircraft operations, which must consider the highest elevations for safe navigation.