20 / 20
You are flying in the mountains. Which error will occur with your altimeter due to the Venturi effect?
  • A
    The altimeter overreads. The wider the valley, the greater the error.
  • B
    The aircraft is higher than indicated. The effect decreases with decreasing wind speed.
  • C
    The altimeter overreads. The higher the wind speed, the greater the error.
  • D
    If you are flying with a tailwind, the altimeter underreads; if you are flying with a headwind, it overreads.
The mountains will create a sort of Venturi ‘throat’ that will make the wind to converge between the valleys. Therefore, the wind speed will increase, and the pressure will drop. A decrease in ambient pressure will make the altimeter over-read as the aircraft’s true altitude will be actually lower.

Your Notes (not visible to others)

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