This is the KLN94 today.
However APR mode (whatever that means) was not inhibited. The paths for LFAT RNP31 and EGKA RNP02 loaded and flew perfectly.
We have many NOTAMs about GNSS jaming over France, there are military exercises on going, it may be related to this.
AIUI, RAIM is derived 100% from the satellite constellation geometry. That’s why a GPS can predict it for you. You can determine – algorithmically – whether there will be a RAIM outage 1100Z-1200Z on 25th May 2027.
No GPS (in GA usage) can detect any kind of jamming.
It is the 2nd line I don’t get, because it seems false.
Did you check RAIM availability prior to the flight?
If not the tool is called AUGUR. Click on the Terminal/Approach Tool (on top of the page) and then on the left you can enter e.g. airport identifiers etc.
https://augur.eurocontrol.int/
However, about the KLN94 I don’t have any experience.
Yesterday, right next to kaliningrad border. Garmin 430 was fine though.
That is GPS jamming, not related to RAIM.
RAIM is also not specifically related to the KLN94 although the KLN94 emits that weird message about not doing “APR”.
IIUC RAIM is not only satellite geometry, but also affected by outages of individual satellites.
On Friday, there was an AUGUR indicated RAIM outage around lunchtime – in training you always check ;-)
Also, this does not make the GPS disfunctional, it merely means that the on board integrity check couldn’t be done… increasing the risk. The indicated position is not certain.
I would guess, that APR mode inhibited to mean that the box stays in cruise sensitivity and does not switch to approach mode.
Par
I’m not familiar with Lithuania. What sort of ground based aids are they and are they sufficient?
RAIM is an algorithm based on Geometry. It can be enhanced with FDE (Foult Detection and Elimination) and with Baro Aiding. RAIM Available means the algorithm has sufficient satellites with satisfactory geometry for the algorithm to calculate a RAIM statistic, measured in meters of a radius within which the true position lies with very high confidence. A GPS lateral position requires 3 satellites, if including a vertical position, it needs 4 satellites. To calculate RAIM, one needs a fifth satellite or a valid baro altitude. So even if RAIM can’t be calculated, it does not mean the position is inaccurate, it just means you don’t know if it is trustworthy. That is why if you have RAIM available at the FAF, but lose it during an approach, you may continue the approach to the MAP.
A RAIM statistic for LNAV approach requires 0.3 NM or 556 meters. So even though there was a big solar storm on 5/10/2024 into 5/11/2024, a TSO C129 navigator would not have had a failure indication. For a WAAS/SBAS Navigator such as a GNS/W or GTN Garmin navigator, RAIM is irrelevant and not used at all to determine integrity of the position as long as the aircraft is in the SBAS SV because the Geostationary SBAS satellites broadcast the integrity information directly to the navigator. The SBAS statistic is HPL and VPL with both measured in meters. Each PBN operation requires its own HAL and VAL Alert Limits, so for RNP APCH, LNAV HAL requires less than 556 meters, LP requires less than 40 meters. For LPV, HAL is 40 meters and with those procedures with a DH >= 250 feet, VAL is 50 meters and for LPV200, VAL is 35 meters. So although the solar storm wiped out LP and LPV service, it had no impact on LNAV service.
The mystery of the “APR mode inhibited” thus remains. It worked just fine 
