Originally Posted by
gipsymagpie
Sorry - but cheeky about the AIRAC date - I see the date on the GTN every time I start the aircraft and know with a sinking feeling that I’ll be the one doing the update in the aircraft if I actually want the database to be up to date.
So I don’t think the whole approach will go, just the minima - laterally an LNAV is identical to an LPV and can be flown without any SBAS at all so the LNAV will definitely endure.
I can see where you are coming from regarding the “overlay” but that’s something very specific to “overlaying” SBAS on a lateral conventional procedure. Certainly our aircraft are certified to 3D couple to the SBAS generated 3D LNAV/VNAV information. They will not couple to the advisory glideslope published for LNAV+V.
So here’s an interesting document from the CAA to ponder:
https://www.euroga.org/system/1/user..._Questions.pdf
At question 6:
The end of EGNOS EWA agreements will only impact the LPV elements of an RNP APCH IAP, therefore only the LPV lines of minima within RNP IAPs will be NOTAM’d as unavailable, before subsequently being withdrawn.
LNAV (and LNAV/VNAV) lines of minima published on RNP APCH IAPs will continue to be available. There is currently no alternative to the EGNOS SoL service available in the UK or envisaged in the short term.
Perhaps Alex with your status in the real world could ask the CAA the following:
Can LNAV/VNAV be flown using SBAS in the UK in accordance with para 5.4.4.2 of Vol 1 of PANS OPS?
If not could the CAA please provide a clear statement to the community?
I for one will continue to use LNAV/VNAV in accordance with my ops manual.
I feel a terrible sense of dread that whilst I have a comprehensive set of references for this, there is a Luddite in the government who is going to spring up and say we cannot use SBAS for anything and we have to turn it off to prevent contamination of this country with Euro influences.
joy.
Yes, LNAV isn’t affected by this as you say. And as GPS will do the job, those pesky burocratic Europeans can keep their satellites. Fortunately the UK has a pragmatic government that has thought all this through in the years it had to consider the ramifications of Brexit. And its not like it would let stuff like this happen through lack of preparation or to cut off noses our to spite the EU’s face.
A lot of 2D LNAV approaches are flown coupled baro VNAV, because FMS systems default to this when LPV is not one of the approach options (even though the SBAS signal could be received - thus easily programmed out). As we fly CDFAs, there really should be no effective difference as you say. More a question of which minima you are flying to. But it begs the question as to why you cannot fly couple baro-VNAV if your aircraft are IFR certified and otherwise capable of SBAS coupling. Is it because the certification standard for 3D guidance does not extend to the pitot-static system, or that it does not feed into the AFCS?
If the VNAV approach using the EGNOS signal can still be selected, there is little doubt that this is exactly what a lot of people will do. But this is why I believe the database providers will programme this out until the matter is resolved. I mean, seriously, you can’t have people flying down to CAT 1 minima using a system which isn’t bedded in a regulatory framework of agreements. And the use of the only augmentation signal isn’t