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

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

Old 6th Jul 2021, 07:57
  #21 (permalink)  

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DCThumb,

Its obvious what is going to happen in reality….
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Old 6th Jul 2021, 08:22
  #22 (permalink)  
 
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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. 😳
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Old 6th Jul 2021, 08:59
  #23 (permalink)  
 
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It's not an LPV approach anymore, if you apply LNAV/VNAV minima.
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Old 6th Jul 2021, 09:33
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Make it simpler: it's a 3D approach to LNAV/VNAV minima.
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Old 6th Jul 2021, 20:52
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Originally Posted by H Peacock View Post
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 canít 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!)
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Old 7th Jul 2021, 09:12
  #26 (permalink)  
 
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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
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Old 7th Jul 2021, 10:44
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Originally Posted by pilot dude View Post
But an LNAV/VNAV is supposed to be flown on a Baro generated G/P not a satellite generated one, ergo you canít 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.
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Old 7th Jul 2021, 11:20
  #28 (permalink)  
 
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Originally Posted by DCThumb View Post
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.
thatís 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
!
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Old 7th Jul 2021, 11:40
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Originally Posted by DCThumb View Post
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.

​​
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Old 7th Jul 2021, 16:49
  #30 (permalink)  
 
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Originally Posted by gipsymagpie View Post
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.
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Old 7th Jul 2021, 18:11
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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.

Originally Posted by Torquetalk View Post
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)

Scroll to the bottom to the section entitled Doc 8168 - Procedures for Air Navigation Services ó 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.





Originally Posted by Torquetalk View Post
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 Ďopení 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)

Originally Posted by Torquetalk View Post
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.

Originally Posted by Torquetalk View Post
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.
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Old 7th Jul 2021, 18:46
  #32 (permalink)  
 
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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…
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Old 7th Jul 2021, 21:18
  #33 (permalink)  
 
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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 Iíll be the one doing the update in the aircraft if I actually want the database to be up to date.

So I donít 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 ďoverlayĒ but thatís something very specific to ďoverlayingĒ 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 hereís 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 NOTAMíd 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.



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Old 7th Jul 2021, 22:03
  #34 (permalink)  
 
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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? 😡
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Old 7th Jul 2021, 22:36
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Originally Posted by gipsymagpie View Post
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

Last edited by Torquetalk; 7th Jul 2021 at 22:47.
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Old 7th Jul 2021, 22:42
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Originally Posted by H Peacock View Post
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 🙂
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Old 7th Jul 2021, 22:44
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Originally Posted by Torquetalk View Post
Yes, LNAV isnít 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 EUís 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 canít have people flying down to CAT 1 minima using a system which isnít bedded in a regulatory framework of agreements. And the use of the only augmentation signal hasnít.
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).
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Old 7th Jul 2021, 22:48
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Originally Posted by H Peacock View Post
The CAA need to get a grip of this now! What a ridiculous wording of a NOTAM:



Itís absurd that we have 2 opposing Ďanswersí to this: Fly LPV to LNAV/VNAV minima, or donít 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)
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Old 8th Jul 2021, 12:26
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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...
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Old 8th Jul 2021, 12:45
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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....fe-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....en-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.

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