14 / 20

An aircraft is flying at FL300. The OAT = ISA +15°C, The QNH given by a station at an elevation 3000 ft is 1020 hPa.Use 1 hPa = 30 ft.

Calculate the True Altitude rounded to hundreds of feet.

  • A
    26000 ft
  • B
    28500 ft
  • C
    31900 ft
  • D
    22500 ft

True Altitude = Pressure Altitude + Pressure Correction + Temperature correction

TA = PA + 30 (QNH - ST. PRESSURE) + (4/1000 x ISA DEV. x (AIR HEIGHT COLUMN))

As the aircraft is flying a flight level, the pressure set on the altimeter is the standard pressure 1013.The height of the column of air is calculated based in the pressure altitude, to make easier the calculation we will not convert the altitude of the meteorological station to a pressure altitude.

The difference would be minimal and wouldn’t allow us to applied this formula directly, 30 000 - 3000 = 27 000 ft.

TA = 30 000 + 30 (1020 - 1013) + (4/1000 x 15 x 27 000) = 31 830 ft
NOTE: There is other methods that will lead you to same solution, the formula presented is the easiest and fastest way to get the correct answer.

Your Notes (not visible to others)



This question has appeared on the real examination, you can find the related countries below.

Keyboard Shortcut Use Keyboard Shortcuts