What should be done if there is a discrepancy between two altimeter readings during the recording process?

The situation described involves two altimeter readings that differ from each other, which can happen for various reasons, such as instrument error or atmospheric pressure variations. In aviation, having an accurate altimeter reading is critical for safe flight operations, particularly to maintain an appropriate altitude above terrain and other obstacles.

Using the lower reading provides a safety margin; pilots will be less prone to incidental altitude issues that may lead to terrain conflicts or controlled flight into terrain. This approach helps to ensure that the aircraft remains at a safer operating altitude and avoids potential obstacles. The practice of using the lower reading aligns with conservative safety margins that are standard in aviation, prioritizing safety above all else.

Documenting both readings separately might not provide immediate assistance in resolving the discrepancy during flight, while simply averaging the readings could lead to inaccuracies that may affect flight safety. Just using the higher reading could increase the risk of flying lower than intended, posing dangers in areas with significant terrain or obstacles. Hence, opting for the lower reading is a recommended practice to maintain safety in flight operations.