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8.33 kHz Transition - General Guidance

VATSIM UK Operations

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Effective 07 September 2023

EDIT (01/10/2023): The changes to frequencies are now confirmed as permanent, as notified in ATC Procedure Changes.


VATSIM has confirmed the permanent implementation of 8.33 kHz spacing which will increase the range of available frequencies. Changes to frequencies will be notified on this forum.

Although 95% of simulators and addons are believed to have 8.33 radios, there are some pilots who will need to tune these new frequencies manually. It is expected that, at least initially, there will be some difficulties while pilots become familiar with tuning new frequencies. The trial’s purpose is to determine the associated workload increase and any difficulties caused by the ~5% pilots that will need to tune 8.33 frequencies manually.

For details of the transition, visit: vats.im/833


Guidance for Controllers

  • The only frequencies that can be given to one decimal point are non-8.33 frequencies ending in 2 zeroes. All other frequencies must be said to 3 decimal points. e.g. 118.300 may be said as “118.3”, but 118.505 must be said as “118.505”.
  • All controllers will need to more carefully listen to pilot readbacks to ensure all digits are correct. We advocate early use of text where pilots are struggling.
  • Watch out for pilots getting 'stuck' between frequencies and not contacting you/the next controller - they may need help tuning an 8.33 kHz frequency manually.

⚠️ You must update your Sector File and controller pack to ensure correct sector ownership and sector file identification when controlling from the 7th September onwards (2023/09 version).

Once you have updated, if you see any position in the controller list identified with the code <<ERROR, then it means they are using the incorrect frequency. Please direct them to update their sector file and to this forum for details of the correct frequency.



When transferring an aircraft to an 8.33 frequency, if they cannot tune it in their aircraft, they will need to use the .com1 123.455 command in their pilot client.

An Alias will be included in the pack to direct pilots to further help. Please add this alias (or similar) if you don’t use the controller pack.

.833 You have been transferred to an 8.33 kHz frequency. If your aircraft's radio does not allow you to tune the exact frequency, you can use the .com1 command in your pilot client to manually tune it. Visit vats.im/833 for more details

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