A question about RNAV?

[TotalBeginner]

What airspace in the UK does an aircraft have to be RNAV equipped to fly in?

[A and C]

Above FL100 BRNAV is required.

[IO540]

I think the level is actually at/above FL100, but the answer would depend on the reason for asking.

BRNAV is not equivalent to RNAV. BRNAV is a specific equipment performance and certification. RNAV is merely the ability to navigate to virtual waypoints directly, and any GPS with a DCT function delivers that.

There is also the practical aspect. Airways ATC assume everybody has RNAV capability, regardless of FL100 or below, and will happily send you to a VOR 200nm away, treating it as just another waypoint.

In some areas e.g. Greece, ATC expect you to have RNAV capability even on VFR flights and expect reports at specified airways intersections. Nice

Another bit is RNAV STARs - these obviously go below FL100 but you need PRNAV to fly those, and PRNAV is yet another equipment performance, functionality (this one is not defined AFAIK but an auto slewing course pointer i.e. an EHSI is one possibility) and certification level..... probably the majority of European planes with IFR GPS installations cannot legally fly these procedures (usually there is the "advise ATC of you can't" option). This one is a bit of a worry, if large chunks of airspace become "mandatory PRNAV". Anybody with GPS-based RNAV capability can fly there practically (and easily to the required accuracy) but not legally.

[TotalBeginner]

Now I'm confused

Would you mind explaining BRNAV a bit more?

The reason for my question was because of a situation that arose a few days ago. I work in an FBO, and one of our customers had to have their FMS removed from a C525. They wanted to know if they could FPL back to their base in spain without being RNAV equipped. I didn't think it would be a problem provided they remain below RVSM airspace, but I guess it's probably more complicated?

[wigglyamp]

BRNav

The requirement for BRNav is given in EASA AMC20-4. It requires that the aircraft is equipped with a Nav system that can navigate to an accuracy of +/- 5NM cross-track error (RNP-5) and allows the pilot to select a direct-to waypoint which can come from a suitable current database, or can be manually entered (as in the case of a VOR/DME based RNav). Where the system is based solely on GPS data, there is a minimum spec for the GPS of TSO C129a, and additional inputs such as altitude aiding is required.
The system is mandatory for all IFR flight above FL95 in Europe, so your CJ crew shouldn't legally be able to operate without their FMS (as it's their only BRNav source). Some CJ's have a stand-alone GPS in addition to the FMS (possibly a KLN90B or GPS400). However, the requirement in the AMC requires that cross-track error must be presented to the pilot on a standard deviation indicator within the pilot's normal scan, and if two pilot's are required, both must have this display, so a stand-alone back-up GPS cannot be used to meet the BRNav compliance.

The requirements for PRNav are laid down in JAA TGL-10 and require RNP-1, which is more stringent, and have lots of additional certification hurdles before EASA will approve the required AFM supplement.

Hope that helps.

[IO540]

One could work out a Eurocontrol route down to Spain at FL090.

This one has just been tested - Luton to Malaga

-EGGW0900
-N0152F090
CPT N859 DRAKE A34 LGL A55 POI B19 ENSAC R10 BTZ R299 PPN R10 CJN G5 BLN
-LEMG0633
-DOF/080829