Brussels blocking UK from using EGNOS for LPV - and selection of alternates, and LPV versus +V

Some kind of a “deal” has been done and once the details (1k-2k pages) have been published, we may see something in there.

However, from the CAA/DFT press release, I suspect that the lack of an agreement is already in the stuff “provisionally agreed” so there may be no change, until a separate agreement is reached. The DFT is likely to be hoping to do some sort of an agreement before the CAA forces the relevant airfields to notam the LPV approaches as unusable, and then there will be a month or two before Jepp remove them from their database.

IMHO the +V mode will remain usable because while it does need WAAS/EGNOS (“SBAS”), it does not need any airport-specific procedure in the navigator database, and thus even if UK LPV procs were stripped out, the +V would remain available – because the signal itself will remain receivable. And, frankly, all people who are LPV capable will also be +V capable, and IMHO most of those who have +V will just fly the +V glideslope to the LPV minima You just can’t do this on your IR test.

For an approach approved for LNAV/VNAV using Baro Vnav to be used with SBAS GPS data instead for the vertical component, it requires that the FAS datablock contains an additional code letter. Originally the UK didn’t permit this although some EU countries did (Germany at least). So if we don’t have EGNOS and LPVs are removed from the AIRAC cycle, it’s likely the data-block for a Baro Vnav will also have the GPS activation coding removed.

+V would remain, however, yes?

I don’t even know what BARO/VNAV is… I vaguely recall it was blocked from the navigator options if LPV was available, but later this changed, and anyway which navigators support it, and does it do anything useful?

The GNS-W and GTN can fly Baro Vnav approaches using GPS instead of precision baro altitude data. Several UK airports have Baro Vnav approaches – these were available before LPV came along. Baro Vnav is used by aircraft that have much tighter calibrated static systems and static source error correction built in to the air data computers.

I think there are very few of these BARO-VNAV IAPs in the UK.

This has come out, on the GPS portion of the UK-EU agreement. Local copy

Maybe somebody forgot the UK hosts three of the monitoring stations – see page 2 which it should now turn off, and see if anybody in the north of Europe notices

Does anyone in avionics know if the GNS GTN and IFD navigators will pick up EGNOS/WAAS signals on other channels? I would think so because these services exist elsewhere in the world and it can’t be hard-coded for WAAS and EGNOS. Maybe @ncyankee or @steveavidyne knows. Then the UK could rent a transponder on some geostationary satellite and get the same thing. And recover some of the cost from Ireland

Peter wrote:

I would think so because these services exist elsewhere in the world and it can’t be hard-coded for WAAS and EGNOS.

There are few enough SBAS services that they could well be hard coded in the software.

The general concept of SBAS has a number of channels available and I would expect the WAAS navigator to search through these at power-up.

For example when you buy an IFD540, and install it in the US, or install it in the UK, is there a country-specific config? Looking in the IFD540 IM:

No other mention of SBAS or any kind of country setting, and it would be daft because you would not be able to cross the boundary from WAAS to EGNOS on a flight US to Europe, without reconfiguring the box.

Some info on google example wiki. More here. PRN assignments local copy. There are lots of these.

Whether the UK (and Ireland) could radiate its own SBAS signal, with some coverage inevitably straying over mainland Europe, and do it on channels which are available and are supported by current avionics, is another question… but you can do quite a lot for €30M and support some domestic expertise at the same time which is always a good proposition at these times The UK already has a high-end satellite technology industry.

Given the super low use of EGNOS in the UK so far, it would be funny to see a UK SBAS system

That’s very true; nobody will spend a single penny in the UK doing something good in the airspace/navigation sphere, for GA. However, there are some commercial LPV users, plus probably surveying applications (not sure if differential GPS uses SBAS). Also the southern UK EGNOS stations must be used to support coverage for N France… unless there are backup stations, intended for a brexit scenario, which can come online quickly.