On Tuesday, July 15, VATSIM will conduct a 24-hour global test of its enhanced voice communication system. The test will run from 0000z to 2359z and will introduce a new feature: Terrain-Based Ranging, aimed at simulating the real-world effects of geography on radio transmissions.
During the test, pilots may experience reduced or interrupted voice communication with air traffic control or other aircraft when flying at low altitudes, through valleys, or near significant terrain obstructions. This behavior is intentional, designed to reflect how terrain affects VHF radio performance in real-world aviation.
To support users during the test, text communication will remain available as a fallback in areas where voice coverage is limited or unavailable. VATSIM is encouraging pilots and controllers to be prepared to use text messaging if voice connectivity becomes unreliable due to terrain interference.
As part of the upcoming rollout, VATSIM Tech is also planning to release a public endpoint that allows users to retrieve approximate terrain altitude data at given geographic coordinates. This tool is expected to help developers and users better understand the voice coverage model and prepare for the future implementation of terrain-aware features.
VATSIM has not confirmed when or if Terrain-Based Ranging will become a permanent feature, but results from this test will likely inform that decision. Users are encouraged to participate and report any notable experiences through the official feedback channels. If you crave more information from the flight simulation world, check out our FSExpo2025 page with many fresh announcements.
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