Private Pilot Private Exam

When transitioning to a higher elevation, how does the altimeter behave if not adjusted?

1. It will indicate altitude accurately

2. It will indicate a lower altitude

3. It will indicate an increased altitude

4. It will display erratic readings

The correct answer is: It will indicate a lower altitude

When transitioning to a higher elevation without adjusting the altimeter, it will indicate a lower altitude. This occurs because altimeters are calibrated based on the standard atmospheric pressure at sea level, which is typically set to 29.92 inHg or 1013.25 hPa. As you ascend to a higher elevation, the atmospheric pressure decreases, but if you do not make the appropriate adjustment, the altimeter continues to read as if you are at the previous pressure setting, leading to an incorrect reading that suggests you are at a lower altitude than you actually are. This discrepancy can create a dangerous situation, as pilots may mistakenly believe they are at a lower elevation, increasing the risk of terrain collisions. Therefore, it's crucial to reset the altimeter to the local barometric pressure reported at the new elevation to ensure accurate altitude readings and maintain safe flight operations.