Application and guidance information regarding Basic Area Navigation (B-RNAV)
B-RNAV permits aircraft to navigate above FL95 without the use of point source navigation aids. This allows direct tracks and fuel savings provided that track keeping accuracy is +/- 5 nautical miles of the displayed position for at least 95% of the time.
The Air Navigation Order 2009 (Article 124) states that an aircraft cannot fly in airspace designated for B-RNAV purposes unless it is properly equipped and approved to do so.
In UK airspace, the only requirement is that an aircraft is fitted with equipment certified as supporting operations.
Should an aircraft owner/operator be required to hold an approval when operating in airspace outside of the UK, application should be made to the CAA.
FODCOM 04/08 - "Area Navigation (RNAV) CAA Guidance Material"