What should a pilot do if the altimeter is not functioning correctly?

Using GPS-derived altitude information when an altimeter is malfunctioning is a prudent and effective strategy for pilots. GPS can provide accurate altitude data based on satellite information, allowing a pilot to maintain situational awareness regarding their altitude above mean sea level or terrain. This is particularly vital in situations where altitude discrepancies could lead to unsafe flight conditions, such as during approach and landing phases.

By reporting any discrepancies encountered with altitude information, the pilot contributes valuable information for air traffic control and enhances overall safety for both the pilot and other aircraft in the vicinity. This step ensures that all parties are aware of the situation and can take appropriate actions if necessary.

Continuing to fly without addressing the malfunction, landing immediately without assessing the situation, or attempting to recalibrate the altimeter in-flight are not advisable actions and could lead to increased risk during the flight.