No LPV approaches in UK from 26th June due to Brexit

[custardpsc]

I just stumbled upon this.

https://publicapps.caa.co.uk/docs/33/EGNOS_V4.pdf

"Without the use of the European ‘augmentation system’, and in close co-ordination with the affected aerodromes, NOTAMs are being issued to notify pilots that LPV lines of minima on the RNP IAPs are not available for use from the 25 June 2021 until further notice"

"The end of the EGNOS agreement in the UK will only impact the LPV elements of an RNP APCH (Instrument Approach Procedures) IAPs approach, so only the LPV line of minima will be NOTAM’d as unavailable, before being withdrawn. LNAV (Lateral Navigation only) and LNAV/ VNAV (Lateral and Barometric VNAV) lines of minima published on RNP APCH will continue to be available"

I did look at a few airport notams and no sign of the LPV minima being withdrawn ?

[ShyTorque]

Presumably you are aware that all IR holders now need to be PBN qualified to retain said privileges.

[Aso]

That means you are back to good old non precise systems... Great... :(

Is it correct that one Medical flight already had to divert due to this?

[gipsymagpie]

That document is dreadful; it's full of half truths and doesn't actually say what has happened. It needs to be withdrawn before everyone gets the wrong idea.

What we have lost is access to the EGNOS Safety of Life (SoL) service which is a pre-requisite for LPV approaches. However, the EGNOS Open Service (which is free) is still available so your GPS will still get a useable SBAS augmentation signal. This means that LNAV, LNAV+V and LNAV/VNAV (using SBAS for vertical guidance) will continue to be available. The CAP fails to mention nearly every aspect of that.

Practically at most airports you won't see much difference. Indeed at Cardiff the LPV and LNAV/VNAV minima are nearly identical. At some places where the LNAV/VNAV minima weren't included then the difference from LPV to LNAV minima is bigger - possibly up to 3-400 feet.

But it's the potential of LPV to replace Cat I ILS that we have lost. The Channel Islands had some of the only LPV 200 approaches in the UK but these should have been at every instrument airport by now. Hopefully someone pulls their head out of the sand at UK plc and renegotiates access to the SoL.

[ShyTorque]

As a long term IR holder, I was obliged by the CAA to qualify (like many others and at quite a large expense) to fly these approaches, or lose my existing IR privileges altogether. Now we’re told we cannot use them to the full extent of an “old tech” precision approach. That’s progress?

A disgrace.

Whats happened in effect is that the “vertical enhancement” signals still exist and will be received by the aircraft equipment but we are not allowed to use them. It’s the same as not being allowed to watch TV at all if the viewer doesn’t pay the BBC for a licence.

[FlyingStone]

Hopefully someone pulls their head out of the sand at UK plc and renegotiates access to the SoL.

Seems quite unlikely unless EGNOS drops European from its name, given the present state of UK politics.

[DCThumb]

Hopefully someone pulls their head out of the sand at UK plc and renegotiates access to the SoL.

Regrettably a negotiation requires 2 parties - my understanding is that the demands being made for access to the system were beyond unreasonable - especially as we part-funded the system in the first place.

[frenchfries4u]

NOTAM C5660/21: Newcastle Airport (EGNT)E) LPV LINES OF OCA(H) DISPLAYED ON THE RNP INSTRUMENT APPROACH CHARTS ARE NOT AVAILABLE FOR USE.

CREATED: 08 Jun 2021 13:36:00 SOURCE: EUECYIYN

[His dudeness]

Regrettably a negotiation requires 2 parties - my understanding is that the demands being made for access to the system were beyond unreasonable - especially as we part-funded the system in the first place.

Well, no one is as good in dealing out cold blooded revenge as bureaucrats are. And the EU is the top of bureaucrat mountain. They will never forgive the UK making their always save jobs less save....

[Giuff]

Well, no one is as good in dealing out cold blooded revenge as bureaucrats are. And the EU is the top of bureaucrat mountain. They will never forgive the UK making their always save jobs less save....

you've been sold a broken toy and still argument about the "bad" EU people...
Let it go mate.

[H Peacock]

Regrettably a negotiation requires 2 parties - my understanding is that the demands being made for access to the system were beyond unreasonable - especially as we part-funded the system in the first place.

How did anyone ever think the EU would be anything but!? Very naive!! 😬

Anyway, so it’s now left to me in the cockpit to deselect (or not) EGNOS to force the LNAV/VNAV to be loaded into the FMS instead of the LPV? 🤔
So why can’t KLM still use the LPV going in to Humberside, surely they are entitled to use EGNOS anywhere it’s available. I therefore assume I can still legally fly the LPV into Frankfurt!

[Torquetalk]

This means that LNAV, LNAV+V and LNAV/VNAV (using SBAS for vertical guidance) will continue to be available. The CAP fails to mention nearly every aspect of that.

When you select type of approach, your guidance system will select the sources to display,.If you fly the LPV, you are not seeing the baro generated -VNAV cue, you are seeing the SBAS-generated cue.

The CAP document cannot say that the signal is still available, as this would encourage people to fly unlawfully. And it isn’t available. The NOTAM says that. It is just still there.

[gipsymagpie]

When you select type of approach, your guidance system will select the sources to display,.If you fly the LPV, you are not seeing the baro generated -VNAV cue, you are seeing the SBAS-generated cue.

The CAP document cannot say that the signal is still available, as this would encourage people to fly unlawfully. And it isn’t available. The NOTAM says that. It is just still there.

You are confusing what has been lost here. It’s the SoL service we have lost (LPV only) not SBAS. You can absolutely still use this as it is part of the Open (free) part of EGNOS. LNAV/VNAV in most light aircraft has only ever been based on SBAS Open Service and never the SoL. I know we are not seeing the Baro VNAV as it is highly unlikely to be fitted to non-airliners. The LPV and LNAV/VNAV are the exact same flight path in the sky. PANS OPS, the ICAO spec for approaches, CS-ACNS the certification spec for navigation equipment and the appropriate information in the older AC-20 all highlight that any LNAV/VNAV certified for VNAV Baro may be flown with VNAV SBAS (and checked via NATS and the CAA).

So provided you fly to the LNAV/VNAV minima not the LPV minima you are perfectly legal even if your navigation equipment says LPV (that’s just a prioritisation logic). I understand why you might think that from the archaic information pushed out by the CAA in their latest CAP but some reading around the topic will confirm everything outlined above.

LNAV/VNAV may be flown with SBAS VNAV - fact - see CS-ACNS
Only LPV minima have been NOTAMed as unavailable - fact
Therefore you can fly LNAV/VNAV using SBAS where the minima are shown. The anomaly that your particular nag kit shows LPV will be remedied in the next AIRAC.

[gipsymagpie]

You are confusing what has been lost here. It’s the SoL service we have lost (LPV only) not SBAS. You can absolutely still use this as it is part of the Open (free) part of EGNOS. LNAV/VNAV in most light aircraft has only ever been based on SBAS Open Service and never the SoL. I know we are not seeing the Baro VNAV as it is highly unlikely to be fitted to non-airliners. The LPV and LNAV/VNAV are the exact same flight path in the sky. PANS OPS, the ICAO spec for approaches, CS-ACNS the certification spec for navigation equipment and the appropriate information in the older AC-20 all highlight that any LNAV/VNAV certified for VNAV Baro may be flown with VNAV SBAS (and checked via NATS and the CAA).

So provided you fly to the LNAV/VNAV minima not the LPV minima you are perfectly legal even if your navigation equipment says LPV (that’s just a prioritisation logic). I understand why you might think that from the archaic information pushed out by the CAA in their latest CAP but some reading around the topic will confirm everything outlined above.

LNAV/VNAV may be flown with SBAS VNAV - fact - see CS-ACNS
Only LPV minima have been NOTAMed as unavailable - fact
Therefore you can fly LNAV/VNAV using SBAS where the minima are shown. The anomaly that your particular nag kit shows LPV will be remedied in the next AIRAC.
Some bedtime reading on how LNAV/VNAV came to be flown using SBAS.

https://www.easa.europa.eu/sites/default/files/dfu/certification-docs-certification-memorandum-'final'-EASA-CM-AS-002-Issue-01_Revision-01_Clarifications-to-AMC-20-27_PUBL.pdf

[gipsymagpie]

How did anyone ever think the EU would be anything but!? Very naive!! 😬

Anyway, so it’s now left to me in the cockpit to deselect (or not) EGNOS to force the LNAV/VNAV to be loaded into the FMS instead of the LPV? 🤔
So why can’t KLM still use the LPV going in to Humberside, surely they are entitled to use EGNOS anywhere it’s available. I therefore assume I can still legally fly the LPV into Frankfurt!
It's all to do with the airport not the aircraft operator. The SoL service paried with a working agreement between the airport and EGNOS (an EWA) meant that EGNOS was legally responsible not the airport for service level provision (particularly the 6 secs to highlight a satellite failure during an LPV). Without the EWA (which are no longer valid), there is no longer teh right legal backstops in place. So airports cannot use LPC any more.

You also do not need to deselect EGNOS. The open service is still completely legal to use and that is what is required for LNAV/VNAV. You just switch to the higher LNAV/VNAV minima.

[pilot dude]

You are confusing what has been lost here. It’s the SoL service we have lost (LPV only) not SBAS. You can absolutely still use this as it is part of the Open (free) part of EGNOS. LNAV/VNAV in most light aircraft has only ever been based on SBAS Open Service and never the SoL. I know we are not seeing the Baro VNAV as it is highly unlikely to be fitted to non-airliners. The LPV and LNAV/VNAV are the exact same flight path in the sky. PANS OPS, the ICAO spec for approaches, CS-ACNS the certification spec for navigation equipment and the appropriate information in the older AC-20 all highlight that any LNAV/VNAV certified for VNAV Baro may be flown with VNAV SBAS (and checked via NATS and the CAA).

So provided you fly to the LNAV/VNAV minima not the LPV minima you are perfectly legal even if your navigation equipment says LPV (that’s just a prioritisation logic). I understand why you might think that from the archaic information pushed out by the CAA in their latest CAP but some reading around the topic will confirm everything outlined above.

LNAV/VNAV may be flown with SBAS VNAV - fact - see CS-ACNS
Only LPV minima have been NOTAMed as unavailable - fact
Therefore you can fly LNAV/VNAV using SBAS where the minima are shown. The anomaly that your particular nag kit shows LPV will be remedied in the next AIRAC.

Not knowing how your airplane works on most of the airplanes I’ve flown you have to download the approach from the database. As soon as you download a LNAV/VNAV approach it will load this approach and will use a BARO calculated VNAV path and not an SBAS glide path. It will use a more accurate GPS position for determining the position of your plane but the VNAV path and the SBAS path are two entirely different path systems. with the BARO VNAV the GS beam is straight and a dot deviation at 6 miles will be the same as a dot deviation at 0,5 NM from the runway. The LPV glide path will get more sensitive as it gets closer to the runway. In short, UK doesn’t have LPV capability and an LNAV/VNAV approach is not the same as an LPV approach.

[gipsymagpie]

Not knowing how your airplane works on most of the airplanes I’ve flown you have to download the approach from the database. As soon as you download a LNAV/VNAV approach it will load this approach and will use a BARO calculated VNAV path and not an SBAS glide path. It will use a more accurate GPS position for determining the position of your plane but the VNAV path and the SBAS path are two entirely different path systems. with the BARO VNAV the GS beam is straight and a dot deviation at 6 miles will be the same as a dot deviation at 0,5 NM from the runway. The LPV glide path will get more sensitive as it gets closer to the runway. In short, UK doesn’t have LPV capability and an LNAV/VNAV approach is not the same as an LPV approach.

Ah fair point. My system is only certified for the LNAV/VNAV SBAS not LNAV/VNAV Baro. The LNAV/VNAV SBAS approach is a combo of an LNAV (linear) and a VNAV SBAS (angular). But the Garmin 750 we have actually flies LNAV as angular (go figure). This means the indications for an LPV (angular lateral and vertical) are identical to the LNAV/VNAV SBAS (angular lateral and vertical on a Garmin). Hence practically in my installation LPv and LNAV/VNAV are the same.

[ShyTorque]

Thank goodness, now that horribly complicated ILS is obsolescent, it's all so simple..... :\.
That's what they call progress...:ugh:

[H Peacock]

You also do not need to deselect EGNOS. The open service is still completely legal to use and that is what is required for LNAV/VNAV. You just switch to the higher LNAV/VNAV minima.

Thanks Gipsymagpie, however the Garmin G1000 doesn't allow you to choose which type of PBN approach you load. If it sees SBAS as active, you can load the LPV but not LNAV/VNAV, the latter can’t be seen as an available approach. The only way to see and load the LNAV/VNAV is to disable SBAS before you load the approach; SBAS can then be reselected leaving the LNAV/VNAV approach active.

[DCThumb]

I think the TV license analogy is perfect. The EGNOS signal is still there. The UK based RIMS 'will continue to operate' (I do hope we have increased the rent accordingly!) and 'there is no need to de-select the EGNOS signal from GPS' - according to the CAA.

The CAA update states that 'only the LPV line of the minima is unavailable' which to me reads as 'you can still fly an angular approach, but it must be terminated at the LNAV/VNAV minima' and this is reinforced by the article in Flyer where the man from the ministry says:

"The CAA is not expecting pilots to disable EGNOS within the equipment and indeed, on some models such an action may not be straight forward."

"The CAA is therefore content to let the avionics box select the highest integrity approach mode available, but any approach should only be flight-planned and flown to the LNAV minima. LPV operations are not available.”

So the colour TV signal is still there....you just have to watch in the non-HD channels!

[ShyTorque]

DCThumb,

Its obvious what is going to happen in reality….

[H Peacock]

Ah, okay, so we can still fly LPV approaches in the UK, ie they are still available at Cardiff, Humberside, Newcastle etc, but they must be flown to LNAV/VNAV minima?! 🤔

Best I go and re-read the pertinent NOTAMs. 😳

[FlyingStone]

It's not an LPV approach anymore, if you apply LNAV/VNAV minima.

[EatMyShorts!]

Make it simpler: it's a 3D approach to LNAV/VNAV minima.

[gipsymagpie]

Thanks Gipsymagpie, however the Garmin G1000 doesn't allow you to choose which type of PBN approach you load. If it sees SBAS as active, you can load the LPV but not LNAV/VNAV, the latter can’t be seen as an available approach. The only way to see and load the LNAV/VNAV is to disable SBAS before you load the approach; SBAS can then be reselected leaving the LNAV/VNAV approach active.
GTN 750 is probably the same but I don't think it's a necessary step. Fly with the LPV indications but to LNAV/VNAV minima as mentioned above. It's pretty similar to a Cat III ILS. All the indications would be correct down to the runway but we usually go around at Cat I minima (yes I know Cat III to the ground would require a fail-active AFCS and lots of training but it's my analogy - you don't have to like it!)

[pilot dude]

But an LNAV/VNAV is supposed to be flown on a Baro generated G/P not a satellite generated one, ergo you can’t fly a LNAV/VNAV with an SBAS G/P

[DCThumb]

But an LNAV/VNAV is supposed to be flown on a Baro generated G/P not a satellite generated one, ergo you can’t fly a LNAV/VNAV with an SBAS G/P

The key is 'supposed to'. The CAA seem to have taken the surprisingly pragmatic view that the more precise signal is available and useable, and that if you fly that GP to LNAV/VNAV minima then there are no safety concerns.

[pilot dude]

The key is 'supposed to'. The CAA seem to have taken the surprisingly pragmatic view that the more precise signal is available and useable, and that if you fly that GP to LNAV/VNAV minima then there are no safety concerns.

that’s the same as saying a LPV is more accurate then a CAT I ILS so I can fly my LPV to ILS so I can fly LPV to CAT I minima.
LPV and LNAV/VNAV us different equipment so to substitute the one for the other is against regulations. Even for the UK
!

[gipsymagpie]

The key is 'supposed to'. The CAA seem to have taken the surprisingly pragmatic view that the more precise signal is available and useable, and that if you fly that GP to LNAV/VNAV minima then there are no safety concerns.

That's not right. The CAA haven't taken a pragmatic view it's the regulations that changed. ICAO have decided that all LNAV/VNAV can be flown with SBAS for vertical guidance - it's fine, seriously. Go read PANS OPS and CS-ACNS.

​​

[Torquetalk]

That's not right. The CAA haven't taken a pragmatic view it's the regulations that changed. ICAO have decided that all LNAV/VNAV can be flown with SBAS for vertical guidance - it's fine, seriously. Go read PANS OPS and CS-ACNS.

​​

ICAO does not have jurisdiction, the competent authority in each country does. And it can deviate from ICAO as it sees fit.

What is needed is a reference to the UK CAA permitting SBAS for LNAV/VNAV guidance, even for baro approaches, and even though it now has no agreement in place with the authority which provides the signal. The Open Skies principle will not suffice for this; ditto SoL, which is merely a standard anyway.

Perhaps it would be helpful if you could paste in, or at least reference, exactly the pertinent passages of the regulations you are referring to. That would prove the point and stop each ppruner scuttling off to scour the regs.

Once these NOTAMS get worked into the AIP, assuming the matter is not promptly resolved, an update of your Garmin database will simply see the SBAS option disappear for all UK airfields. That could be in about 56 days time. Or 28 if they are really snappy.

[gipsymagpie]

Thanks, this is worth clarifying. As Alex mentions this is worth explaining properly - below is a holding message to wet your appetite. I will provide the full explanation interfrastically.

ICAO does not have jurisdiction, the competent authority in each country does. And it can deviate from ICAO as it sees fit.

Yes, completely correct. The CAA can deviate if it sees fit BUT it must inform ICAO as a contracting state (thank you Alex for a good education at your establishment!). A summary of the non-conformities is published helpfully on the net.

GEN 1.7 DIFFERENCES FROM ICAO STANDARDS, RECOMMENDED PRACTICES AND PROCEDURES (nats.co.uk) (https://www.aurora.nats.co.uk/htmlAIP/Publications/2018-11-08-AIRAC/html/eAIP/EG-GEN-1.7-en-GB.html?amdt=show)

Scroll to the bottom to the section entitled Doc 8168 - Procedures for Air Navigation Services — Aircraft Operations Vol I (Flight Procedures) (4th Edition).

Check the list for the following paragraph number in Vol 1....para 5.4.4.2. You won't find it which means your instrument procedure is designed to that standard in the UK.

And what does 5.4.4.2 say? Ta da! If you look in the FLM supplement for your particular nav equipment it will indicate whether your device is certified to take advantage of this.
https://cimg3.ibsrv.net/gimg/pprune.org-vbulletin/1697x509/sbas_4_b19820380fd04aa7ee2456b16e67e58bd3f395c2.jpg




What is needed is a reference to the UK CAA permitting SBAS for LNAV/VNAV guidance, even for baro approaches, and even though it now has no agreement in place with the authority which provides the signal. The Open Skies principle will not suffice for this; ditto SoL, which is merely a standard anyway.

CAA has permitted it in accordance with conformity with ICAO SARPS above. As per the following document "...UK businesses and organisations are able to use the freely available ‘open’ signal to develop products and services for consumers, and can use the open position, navigation and timing services provided by Galileo and EGNOS." but "...Any UK users of the EGNOS Safety of Life (SoL) service should make preparations for mitigating the loss of this service from 25 June 2021." SoL signal is only required for LPV (it is very specific - further explanation later) not for LNAV/VNAV and SBAS in general.

UK involvement in the EU Space Programme - GOV.UK (www.gov.uk (https://www.gov.uk/guidance/uk-involvement-in-the-eu-space-programme))

Perhaps it would be helpful if you could paste in, or at least reference, exactly the pertinent passages of the regulations you are referring to. That would prove the point and stop each ppruner scuttling off to scour the regs.

Holding explanation above - detail to follow.

Once these NOTAMS get worked into the AIP, assuming the matter is not promptly resolved, an update of your Garmin database will simply see the SBAS option disappear for all UK airfields. That could be in about 56 days time. Or 28 if they are really snappy.

Not quite. The next AIRAC is 8 days away, so probably then (25 June 2021 fell midway between AIRAC hence NOTAMs required). You will probably see the LPV minima disappear leaving LNAV/VNAV minima where provided (eg Cardiff). As highlighted above SBAS can be used for LNAV/VNAV. Longer explanation to follow once I extract the info from the remaining regulations.

[Torquetalk]

Good job gipsymagpie 👍

I didn’t actually count the days til the next cycle, how diligent of you 😉

I suspect the LPV minima won’t just disappear off the approach plates, but that the database provider will also delete the approach. So even if the signal is there, you won’t be able to load the approach anyway. That is, until the authorities can get an agreement in place so there is a regulatory bias for continuing to do LPV approaches.

Importantly, does 5.4.4.2 mean what you would like it to? I read it as a basic rule to approve the use of SBAS capable equipment to fly a published SBAS overlay procedure of an existing VNAV baro approach. That isn’t the same as flying the baro VNAV approach whilst actually looking at GNSS signals for vertical guidance.

Your Garmin doesn’t need Galileo or EGNOS; it can use the GPS system (and GLONASS?) - but only for lateral guidance without EGNOS…

[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_files/files/000/051/183/51183/1c4033ae6/original/European_Geostationary_Navigation_Overlay_Service_%28EGNOS%2 9-Frequently_Asked_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.

[H Peacock]

The CAA need to get a grip of this now! What a ridiculous wording of a NOTAM:

NOTAMs are being issued to notify pilots that LPV lines of minima on the RNP IAPs are not available for use from the 25 June 2021 until further notice"

It’s absurd that we have 2 opposing ‘answers’ to this: Fly LPV to LNAV/VNAV minima, or don’t fly LPV.

Forget the bloody minima issue, can one now fly an LPV in the UK, yes or no? 😡

[Torquetalk]

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_files/files/000/051/183/51183/1c4033ae6/original/European_Geostationary_Navigation_Overlay_Service_%28EGNOS%2 9-Frequently_Asked_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

[Torquetalk]

The CAA need to get a grip of this now! What a ridiculous wording of a NOTAM:


It’s absurd that we have 2 opposing ‘answers’ to this: Fly LPV to LNAV/VNAV minima, or don’t fly LPV.

Forget the bloody minima issue, can one now fly an LPV in the UK, yes or no? 😡

I can’t see how you can lawfully fly an LPV to LNAV/VNAV minima personally. But conducting a CDFA to LNAV minima using the LPV profile should be, as those minima do not require precision minima and the profile is almost identical.

Don’t forget the minima; that’s really not a good idea 🙂

[gipsymagpie]

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. 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 hasn’t.
What they might do is code the approaches as they were before 2018. LNAV/VNAV wouldn't load on an SBAS receiver unless you had baro VNAV (I think its via means of changing one parameter on the approach to allow angular vertical VNAV - bit rusty on my ARINC 424 coding).

[gipsymagpie]

The CAA need to get a grip of this now! What a ridiculous wording of a NOTAM:



It’s absurd that we have 2 opposing ‘answers’ to this: Fly LPV to LNAV/VNAV minima, or don’t fly LPV.

Forget the bloody minima issue, can one now fly an LPV in the UK, yes or no? 😡

you absolutely cannot fly to lpv minima. But it specifically says lnav/vnav minima are unaffected. And as shown above lnav/vnav can be flown using SBAS VNAV. So fly the lnav/vnav. Which is identical in 3d space to an lpv. Clear as glass (that opaque stuff in block walls in toilets)

[Alex Whittingham]

Fascinating. Gipsymagpie, thank you. Can't help thinking that when ICAO/EASA accepted SBAS 3D guidance to fly to LNAV/VNAV minima they were assuming SoL or some equivalent was available to provide integrity control, because who would use SBAS without integrity control? Oh...

[gipsymagpie]

Turns out I was wrong. The UK government have utterly thrown us into the dark ages. There is now quite literally no basis for using SBAS for aviation in the UK.

The SoL service as it turns out (do you ever feel like you shouldn't have turned over that stone?) is the whole basis of SBAS usage for any use of SBAS for safety critical aviation use. This means LNAV, the advisory glideslope of an LNAV+V, LNAV/VNAV etc.

So scrap everything I wrote above. Without being able to legally use SoL (which we cannot), you cannot rely on the information at all. This means:

You must check RAIM prior to any approach.
You cannot use the +V advisory glideslope


You cannot fly an LNAV/VNAV unless you have Baro Nav.

The CAA need to actually provide better guidance- they need to highlight these key points about the +V and the VNAV (we have just started using it in anger to log 3D approaches for recency - guess that's in the bin).

The awkward truth is in these two documents. First the service definition of the SoL service from EGNOS:

https://egnos-user-support.essp-sas.eu/new_egnos_ops/documents/egnos-sdd/egnos-safety-life-service-sdd
You can clearly see it mentions NPA, APV and LPV200 as capabilities. And here's the open service...

https://egnos-user-support.essp-sas.eu/new_egnos_ops/documents/egnos-sdd/egnos-open-service-sdd
No mention of any aviation application whatsoever. Indeed it states:

EGNOS OS can only be used for non-safety critical purposes, i.e. purposes that have no impact on the safety of human life and where a failure in availability, integrity, continuity or accuracy of the EGNOS SIS could not cause any kind of direct or indirect personal damage, including bodily injuries or death.

Next time anyone thinks about answering a question on pprune, be careful what you wish for.

[Alex Whittingham]

That's where I got to, although it is difficult information to find and I am still not sure. I think it may come down to legal liability, and although SoL will probably practically provide integrity control for all PBN approaches there is are no longer any legal relationship or obligation on ESA to provide the service and, absent an agreement, continuity of service etc is obviously not guaranteed. My tentative conclusion is that Air Nav Service Providers in the UK should not publish RNP APCH procedures of any sort. I'm finding it very difficult to locate the document that actually says ANSPs have a legal responsibility, though.

This document too (https://egnos-user-support.essp-sas.eu/new_egnos_ops/sites/default/files/library/official_docs/egnos_sol_sdd_in_force.pdf)

[Torquetalk]

My tentative conclusion is that Air Nav Service Providers in the UK should not publish RNP APCH procedures of any sort.

This document too (https://egnos-user-support.essp-sas.eu/new_egnos_ops/sites/default/files/library/official_docs/egnos_sol_sdd_in_force.pdf)

No, that cannot be right Alex, because pretty much all modern devices on board have performance monitoring capability, so RNP is assured for the approach selected OR you get a warning that it is not. GPS signal provision is also unaffected. So LNAV APP no problem; VGP also possible as this is an LNAV non-augmented 2D approach, even if it looks like vertical guidance (and even if your AFCS will couple to it!). That V stands for virtual - you are only supposed to be using it to assist your managed CDFA.

[gipsymagpie]

So somewhat helpfully, one of our GTN 750 equipped types has a full list of what we still have, even though EGNOS SoL (and hence SBAS) is gone. So:

LNAV are fine.
LNAV+V are fine (provided you have the latest firmware in your GTN).
LNAV/VNAV, LP, LPV, LP+V all not fine.

From the flight manual:

https://cimg3.ibsrv.net/gimg/pprune.org-vbulletin/707x366/sbas_10_74c96202264f7a139d9f119a8dfe138ddab4248e.jpg

[Alex Whittingham]

I'm at the limits of my understanding here, but as far as I can determine integrity control comes from 2 sources. 1. ABAS which incorporates RAIM and the normal multi-sensor FMC operation (called AAIM) 2. The GNSS/SBAS signal itself which in the case of EGNOS is the SoL signal as far as RNP APCH is considered. Failure of either #1 or #2 will give you an integrity warning. I believe that RNP APCH requires system integrity control (#2, in other words independant from the aircraft equipment) in order for the approach to be published, it cannot just rely on #1. But I'm really at the limits of what I can find in documentation. Lack of agreement about SoL, for instance, seems to mean no NOTAMs are issued when service is expected to fall below Annex 10 standards in that location.

I have to say I have no confidence in the CAA getting it right. I mentioned the loss integrity control issue implying loss of RNP APCH to Rob Bishworth, the CAA director responsible to Flight Ops, last summer and asked him what he was planning to do about it. He had no idea what I was talking about, it hadn't been 'flagged up in briefings'.

[Alex Whittingham]

From that linked document, in various places, my bold:

The EGNOS Safety of Life (SoL) Service is provided openly and is freely accessible without any direct charge. It is tailored to safety-critical transport applications in various domains, in particular, the service is compliant with the aviation requirements for Approaches with Vertical Guidance (APV-I) and Category I precision approaches1 , as defined by ICAO in Annex 10 [RD-1]

Two EGNOS SoL Service levels (NPA and APV-I) were declared with the first issue of the EGNOS SoL SDD v1.0 in March 2011 and an additional one (LPV-200) was declared with the EGNOS SoL SDD v3.0 in September 2015 enabling the following SBAS-based operations in compliance with requirements as defined by ICAO in Annex 10 [RD-1]: • Non-Precision Approach operations and other flight operations supporting PBN navigation specifications other than RNP APCH, not only for approaches but also for other phases of flight. • Approach operations with Vertical Guidance supporting RNP APCH PBN navigation specification down to LPV minima as low as 250 ft. • Category I precision approach with a Vertical Alert Limit (VAL) equal to 35m and supporting RNP APCH PBN navigation specification down to LPV minima as low as 200 ft.

The European Union, as the owner of EGNOS system, the European GNSS Agency (GSA) as EGNOS Programme manager and ESSP SAS, as EGNOS services provider, expressly disclaim all warranties of any kind (whether expressed or implied) to any party, other than Aviation Users specified under 2.2.2 above [see below], and/or for any other use of the EGNOS SoL Service including, but not limited to the warranties regarding availability, continuity, accuracy, integrity, reliability and fitness for a particular purpose or meeting the users´ requirements. No advice or information, whether oral or written, obtained by a user from the European Union, GSA or ESSP SAS and its business partners shall create any such warranty.

[from para 2.2] EGNOS SoL signal covers also territories outside the EU. However, authorising and safety oversight of the use of EGNOS in civil aviation outside the EU falls within the sole responsibility of the respective third country. ESP will support the operational use of EGNOS based procedures via the signature of the EGNOS Working Agreement (EWA) provided that the level of safety at least equivalent to the Single European Sky requirements can be demonstrated by the interested parties on a case by case basis and that there is an agreement between the EU and the third country on the use of EGNOS SoL

The EWA includes ...... NOTAM Proposal Origination: Outlining the terms and conditions under which the ESSP SAS will provide EGNOS NOTAM proposals to the NOFs of the organisation providing Aeronautical Information Services (AIS) under the scope of a signed EWA

[Torquetalk]

From that linked document, in various places, my bold:

The EGNOS Safety of Life (SoL) Service is provided openly and is freely accessible without any direct charge. It is tailored to safety-critical transport applications in various domains, in particular, the service is compliant with the aviation requirements for Approaches with Vertical Guidance (APV-I) and Category I precision approaches1 , as defined by ICAO in Annex 10 [RD-1]

Two EGNOS SoL Service levels (NPA and APV-I) were declared with the first issue of the EGNOS SoL SDD v1.0 in March 2011 and an additional one (LPV-200) was declared with the EGNOS SoL SDD v3.0 in September 2015 enabling the following SBAS-based operations in compliance with requirements as defined by ICAO in Annex 10 [RD-1]: • Non-Precision Approach operations and other flight operations supporting PBN navigation specifications other than RNP APCH, not only for approaches but also for other phases of flight. • Approach operations with Vertical Guidance supporting RNP APCH PBN navigation specification down to LPV minima as low as 250 ft. • Category I precision approach with a Vertical Alert Limit (VAL) equal to 35m and supporting RNP APCH PBN navigation specification down to LPV minima as low as 200 ft.

The European Union, as the owner of EGNOS system, the European GNSS Agency (GSA) as EGNOS Programme manager and ESSP SAS, as EGNOS services provider, expressly disclaim all warranties of any kind (whether expressed or implied) to any party, other than Aviation Users specified under 2.2.2 above [see below], and/or for any other use of the EGNOS SoL Service including, but not limited to the warranties regarding availability, continuity, accuracy, integrity, reliability and fitness for a particular purpose or meeting the users´ requirements. No advice or information, whether oral or written, obtained by a user from the European Union, GSA or ESSP SAS and its business partners shall create any such warranty.

[from para 2.2] EGNOS SoL signal covers also territories outside the EU. However, authorising and safety oversight of the use of EGNOS in civil aviation outside the EU falls within the sole responsibility of the respective third country. ESP will support the operational use of EGNOS based procedures via the signature of the EGNOS Working Agreement (EWA) provided that the level of safety at least equivalent to the Single European Sky requirements can be demonstrated by the interested parties on a case by case basis and that there is an agreement between the EU and the third country on the use of EGNOS SoL

The EWA includes ...... NOTAM Proposal Origination: Outlining the terms and conditions under which the ESSP SAS will provide EGNOS NOTAM proposals to the NOFs of the organisation providing Aeronautical Information Services (AIS) under the scope of a signed EWA


Too complicated Alex. We have arrived at the info we need to make flight decisions and know why we are making them:

1) Can you load the LPV approach from your on-board NAV system and do you have a plate? Yes? Then you could fly an SBAS approach which is not approved. Should you? What would Jesus do?

2) You cannot load an LPV or don’t have it on the plate: Fly the LNAV approach, which may also be RNP (so what?), using vertical guidance if available to help you fly your CDFA.

3) Fly the Baro-NAV approach to LNAV/VNAV minima if your aircraft is capable of this.

[MarcK]

Is there some physical reason SoL service is no longer authorized for the UK? Is there a UK ground station that is no longer being utilized for corrections? Are the broadcast corrections now being limited to the EU airspace?

[Alex Whittingham]

Too complicated Alex. We have arrived at the info we need to make flight decisions and know why we are making them

Yes, maybe. Well its your little pink body involved in this, not mine, so I will sit back and watch!

[Torquetalk]

Is there some physical reason SoL service is no longer authorized for the UK? Is there a UK ground station that is no longer being utilized for corrections? Are the broadcast corrections now being limited to the EU airspace?

The docs referenced above show no ground stations or coverage UK and NI, unsurprisingly. It is the RIM stations that monitor the geostationary satellites (4 now?), and correct, encode and transmit the SBAS signals to the satellites. Each approach has a specific EGNOS channel and reference, so how hard would it be for these to be delisted?

[gipsymagpie]

The docs referenced above show no ground stations or coverage UK and NI, unsurprisingly. It is the RIM stations that monitor the geostationary satellites (4 now?), and correct, encode and transmit the SBAS signals to the satellites. Each approach has a specific EGNOS channel and reference, so how hard would it be for these to be delisted?

2 RIMS in the UK. They’ve said they will keep them running. The Channel listed against each LPV has nothing to do with any transmission or receipt of a signal. It’s a legacy of how approaches are encoded in FMS. They use the same format as GBAS approaches which were associated with local augmentation transmitters at each airfield. The channel was the output of a mathematical formula based on the VHF frequency used. The aircrew plugged it into their GBAS kit like an ILS frequency. Of course LPV doesn’t have any VHF transmitter but they do need to be unique in the nav database so a big long list of new “channel” numbers were invented. ICAO and the FAA were at various times responsible for allocating these codes to approaches. There is no way of “switching off” channels in the EGNOS system - it’s just a legacy of days gone by.

Also interesting to note all the RIMS in non EU and arguably 3rd world countries who seem perfectly capable of having access to EGNOS from outside the EU….I feel an FOI request coming on here….
https://cimg7.ibsrv.net/gimg/pprune.org-vbulletin/1241x1293/rims_933cb1615f6cf4670a4b634278d37d2d645db19b.png

[gipsymagpie]

Is there some physical reason SoL service is no longer authorized for the UK? Is there a UK ground station that is no longer being utilized for corrections? Are the broadcast corrections now being limited to the EU airspace?
No signal still available - we are surrounded on 4 sides by people who are members of EGNOS…

[tennana]

Gipsymagpie, thanks for trying to come back to me. I'm a new user on PPRuNe and so it seems my inbox is blocked.

[tennana]

I also attach a link to a CAA document Alex had found.
This contradicts itself unfortunately.
www.publicapps.caa.co.uk/docs/33/General%20Aviation%20Partnership%20Slides%20February%202023% 20Quartlerly%20Final%20Slides.pdf