Refer to figure.
QFE is the atmospheric pressure measured at the aerodrome. QNH is QFE which has then been mathematically adjusted down to mean sea level using the airfield's elevation. In simple words, QNH is found by taking aerodrome elevation, converting it into pressure difference and then adding it to QFE. In order to find the QFE from QNH we need to follow the opposite procedure.

The aerodrome elevation of 73 ft has to be converted into hPa of pressure difference. We know that 1 hectopascal (hPa) equates to approximately 30 ft (30 ft = 1 hPa). This means that 73 ft equate to:

• 73 ft / 30 ft = 2.4 hPa ≈ 2 hPa

The pressure difference between QNH and QFE is 2 hPa. We know that atmospheric pressure decreases with altitude. This makes QFE smaller than QNH by 2 hPa (QNH is at mean sea level and QFE is at 73 ft so it is measured at a higher level where the pressure is lower):

• QFE = QNH - 2 hPa = 989 hPa - 2 hPa = 987 hPa

Elevation. The vertical distance of a point or a level, on or affixed to the surface of the earth, measured from mean sea level.

Note: This question is similar to 103846 but you are searching for QFE instead of QNH.