The altimeter indicates the elevation of the airfield based on the local QNH setting. When the altimeter is correctly set to the local QNH value, such as 1018 hPa in this instance, it provides an accurate reading of the airfield's elevation (317 ft). However, if the altimeter is still configured with the departure QNH of 1020 hPa, a difference of 2 hPa (1020 - 1018) exists, causing the altimeter to display a value that is 2 hPa too high. This discrepancy translates to an overestimation of 60 ft (2 hPa x 30 ft/hPa).

• Given the departure QNH of 1020 hPa, during the landing phase, the altimeter would register an elevation of 317 feet plus the excess 60 ft, summing up to a displayed altitude of 377 ft.