L/VNAV and LNAV specs are always available anytime you have the SBAS signal which covers as low as Canaries, Tunisia, Morocco, Iceland…these do not require any “EGNOS licence” paperwork both allow 250ft DH for L/VNAV (APV SBAS) and 350ft DH LNAV (+V with SBAS), I can use these specs in my grass strip in UK without asking anyone !
LPV200 is very special in the sense that one needs an “EGNOS licence” agreement to use SoL it in every AD (@Airborne_Again suggested this happens at national level for EU countries and I think it’s likely AD level outside EU)
The LPV agreement has not much to do with the operational quality of the signal and anyway these are internally checked by our GPS 2nm before the FAF if LPV is loaded in the navigator database, so one should not worry much about it but it has to do with “some EGNOS newsletter” that is sent to AD manager, stuff like “EGNOS wish you a happy Xmas ans safe New Year Eve”…
As far as the pilot is concerned, if LPV leg is coded in GPS database, the GPS will check the quality of signal on final approach and if LPV sign is on HSI one can descend to LPV minima assuming some LPV OCH is published (there could be an AD NOTAMS that prevents the use of that OCH temporary or permanetly but it’s unlikely that RNP NOTAM have any effect on the physical world unless it’s about some dark thermonuclear sky, breeding masts or uncut trees at EDAY)
The LPV final approach course data in the database is contained within a FAS (Final Approach Segment) block. The data block includes a CRC. If any of the data in the data block becomes invalid, then a NOTAM would be issued and a new procedure would need to be developed. I recall in a US situation, a runway number was changed because of drift in the magnetic variation, so the LPV procedure was withdrawn as the runway number designation is part of the FAS data block. Here is a link to a description of the contents of the FAS data block FSIMS Appendix 12 FAS Data Block
Thanks @NCYankee , why the change in runway magnetic number in FAS data block will impact the LPV but not the LNAV?
I expect things like SBAS identifier, HAL/VAL, Visual Descent Angle or GlidePath…would be way more relevant to an LPV than LNAV, but the runway number should impact both?
An LNAV or LNAV/VNAV does not need to have a FAS data block, only an LPV or LP requires the FAS data block.
Got it thanks (LNAV with LP and angular sensitivity would still require FAS, it’s legacy LNAV with lateral sensitivity that does not need one?)
The LP (probably not used in Europe) and LPV require the FAS data block as they are SBAS based procedures. LNAV and LNAV/VNAV do not.
If any of the data in the data block becomes invalid, then a NOTAM would be issued and a new procedure would need to be developed
The Q is how could this have happened? The data block isn’t going to become invalid just by itself.
Peter wrote:
The Q is how could this have happened? The data block isn’t going to become invalid just by itself.
In the example I cited, the runway number was changed. The true course of the runway and all the other data was still the same, but since the approach procedure in the database included the FAS data block, a new procedure had to be issued with the updated data block. It should have been better coordinated so that everything changed at the same time. My guess is that COVID played a hand in the lack of coordination.
Thank you everyone for your inputs. We will see whether the LPV approach will be available again in the future.
Best regards
Christian
Someone on the German PuF forum called the airfield and enquired. The suspension has to do with bureaucratic reasons. Something to do with an official QNH reading needing to be provided to the pilot and the airfield needing to be properly equipped and approved to do this.
Obviously, this is all mostly theoretical only, since even with that NOTAM in place, the glideslope signal remains and it‘s the pilot only who determines when the airfield is in sight or not. Rememer that there are no LPV approaches as such. There are only RNP approaches, and these may be flown down to different minima.
The one strange things that remains is why this lack of local QNH only affects the LPV minima, but not the LNAV minima.
The other strange thing remains why this apparently temporary problem led to a PERM NOTAM.
