How can a pilot obtain the altimeter setting while enroute?

Obtaining the altimeter setting while enroute is essential for ensuring accurate altitude reading and maintaining safe vertical separation from other aircraft. Air Traffic Control (ATC) provides periodic altimeter settings to pilots during their flight. This information is crucial because atmospheric pressure changes can impact the altimeter, which relies on the local barometric pressure to provide altitude readings.

When pilots are flying at cruising altitude, they are expected to use the information given by ATC to update their altimeters accordingly. Altimeter settings can change frequently due to weather conditions and other factors, so regular updates from ATC help maintain altitude accuracy and safety.

Using the onboard altimeter alone does not provide a current setting unless the pilot is actively updating it with the latest information from ATC or other reliable sources. Similarly, personal altimeter devices or calculations based on the last known airport altimeter can introduce errors or may not reflect real-time atmospheric conditions. Thus, relying on ATC's guidance for altimeter settings is the most effective and accurate method for pilots while enroute.