SU7 Issue with OFFLINE ATC text to speech, Azure online services not affected

Since SU7 has been installed I am noticing incorrect text to speech translation for OFFLINE atc voices, Azure seems to be unaffected.

The particular issue seems to affect certain types of clearance and instruction. The video below illustrates the issue.

It seems to be tied to code in en-US.locPak in Official\OneStore\fs-base (or the offline TTS engine being able to decode this correctly). The sort of code producing issues is:

  • Resume (so it’s not pronounced like “résumé”): [p-beg]RA AX . S2 Z U M[p-sep]resume[p-end] own navigation.
  • RNAV (so it’s not spelled out as “R-N-A-V”): [p-beg]S1 AA RA . N AE V[p-sep]r-nav[p-end]
  • Wind (so it’s not pronounced like “wined”): [p-beg]W IH N D[p-sep] Wind [p-end]

(Thanks to @N316TS for helping me track this code down in the affected file)

I got strange spoken words/letters when I got runway clearance.

I hear stuff like “microsoft” appearring in the middle of some utterances. It sounds like the strings being passed to the Voice engine contain metadata/hints which Azure understands and does not ennunciate, but the offline Windows Voice engine does not understand and generates voice output for.


An additional inaccuracy is also concerning traffic warnings or directions by ATC. Any direction using “O’clock” is incorrectly converted from text to speech as something like “oh apostrophe clock”.


Noticing the same here.

“Microsoft” is clearly heard, other words seem a little garbled or just mispronounced maybe?
These extra words are not part of a normal atc response.
I thought it was reading the file header name…

TST in offline mode.

I am getting the same issue since SU7 - ATC speak all the text so = (equals) and {Microsoft) etc, just a load of meaningful rubbish.

I have noticed ‘Microsoft’ a couple of time too. Unexpected but funny :slightly_smiling_face:

1 Like

Text-to-speech service suffering from Tourette’s syndrome :joy:

1 Like

(sorry for that, I couldn’t resist)


Looks like the offline TTS, for some reason, is trying to speak the SSML (Speech Synthesis Markup Language) code that should have been truncated at the user-end. This probably explains the unintelligible speech you hear, for example in OP’s video:

<phoneme alphabet="x-microsoft-ups" ph="<your string here written in Universal Phone Set>"></phoneme>

Here the Universal Phone Set refers to the phonetic alphabet used to synthesize the pronunciation of the string. There’s also some documentation about SSML via Azure’s Speech Service site.

Perhaps some character accidentally got escaped in the TTS side of things?


Just chiming in reporting I’m seeing/hearing the same thing on my end.

Me too. It would be funny if not so annoying. ATC needs a heap of work anyway.

1 Like

Okay so no fix as of yet… got it.

How can these kind of errors not be noticed before release of an update ??

This is realy annoying and shows hows bad Asobo is handling updates.


That’s the one, I’ve definitely heard UPS as well as Microsoft

I also have this problem when I lose connection to the Azure service.

I can see that it is only offline text affected, but for me a have online ATC selected. Get this occasionally.

Same here on takeoff and landing clearances, also traffic advisories. Does anyone know of a fix or a workaround?

One work around is to edit the file
located in the package folder fs-base using a text editor to remove any references to the code put in to educate text to speech (TTS) how to pronounce certain words, that currently are working with Azure TTS but not offline TTS
This could be edited to read

However, this creates other issues and that will now be pronounced off line (and with Azure TTS) as “wind” as in “wind up toy” rather than “wind” as in the thing that blows air around.

So an alternative to “wind” would have to be used, e.g. “wheend”
Similar pronounciation issues occur with “resume” and “rnav” when this code is edited.
Theoretically it is possible and I have experimented with it and got it to work.
However, sticking to azure ATC is what I am currently doing as it isn’t cutting out for me as frequently as it used to.


Tamalien, That worked for me. I can’t remember why I disabled Azure ATC, it was a while ago. Anyway, thanks so much for the tip! - HankLand609

1 Like