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Sensitive Altimeters

Airplanes are almost always equipped with an sensitive altimeter which display altitude based on the ambient air pressure from the static port.

Altimeter Errors​

Because the altimeter is a pressure instrument, it is subject to errors when the external pressure changes. This can be the result of lower or higher atmospheric pressure, or be caused by difference in air pressure.

  • With regard to temperature:
    • When the air is warmer than standard, the pressure is higher
      • The altimeter reads lower than you are actually flying
      • You have a tendency to fly higher than you expect
    • When the air is colder than standard, the pressure is lower
      • The altimeter will read lower than you are actually flying
      • You have a tendency to fly lower than you expect
  • With regards to pressure:
    • When the air has higher pressure than standard, the altimeter will read lower than you are actually flying
    • When the air has lower pressure than standard, the altimeter will read higher than you are actually flying

Remember "high to low, look out below", and "from hot to cold, don't be bold."