How often should you update your altimeter setting during a cross-country flight?

Updating your altimeter setting during a cross-country flight is crucial for maintaining accurate altitude readings, which are essential for safe navigation and separation from terrain and other aircraft. The recommended frequency of every 20 to 30 minutes strikes a balance between ensuring safety and practicality.

During a flight, atmospheric pressure can change significantly, particularly when crossing different weather fronts or geographical regions. Maintaining the correct altimeter setting allows pilots to adjust for these changes, ensuring that their altitude readings remain accurate in relation to sea level. This frequency helps account for variations in pressure that could occur due to changing weather conditions, which can have a direct influence on flight safety.

Updates can also be prompted by passing through areas of significant altitude changes, such as when climbing or descending through varied terrain. Doing so at intervals within this range ensures a pilot remains alert to changes and can respond accordingly, enhancing situational awareness while flying.