ATC in the UK are not allowed to use the term 'Centre Fix' for precisely the reasons you state. We can however clear people direct to 'a X mile final'.
The actual position of the CF will vary depending on aircraft type, coded position in the FMS database if any, or where the pilot places the CF if it's a self constructed procedure.
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PPRuNe Radar
ATC Forum Moderator
[email protected]
[This message has been edited by PPRuNe Radar (edited 12 November 2000).]