Ibra wrote:
During planning: before staring the aircraft one has to check RAIM for RNAV1 terminal legs (departure SID, arrival STAR) and RNP0.3 legs
Here,
https://augur.eurocontrol.int/tool/During flight: by actually pressing Navigator menu and run the check themselves before starting RNAV1/RNP0.3
What you do before the flight is not checking RAIM but checking RAIM prediction for the duration of the flight (or at least the times when you actually need RAIM). There’s no point of doing that once you’re airborne. The box will tell you at once if RAIM is no longer available.
Assuming SBAS is not available or flying non-SBAS TSO129, like KLN or GNS430
Sorry will have to introduce new names & objects 
yes there is RAIM PREDICT: prediction of integrity, this can be run manually by PIC on AUGUR, PIC on GPS and automatically by GPS near FAF, then there is an automatic RAIM FDE: actual integrity check using fault detection and exclusion
Indeed, pressing GPS for “RAIM PREDICT” during flight is largely unessessary but it’s more complicated than that:
1) On ENR cruise, if you are within your IAP EAT the RAIM PREDICT check will be exactly the same one you did in AUGUR before takeoff: it will not notice that giant dinosaur did swallow the whole orbit, I also understand RAIM PREDICT is not required for RNAV5 and RAIM FDE will not run on RNAV leg, 4 satellites to get a position and you are good for RNAV5 cruise?
2) On TERM cruise, RAIM FDE will not run BUT the pilot is expected to have RAIM PREDICT to fly RNAV1 legs (STAR, IAP or simply if you are 30nm from FPL destination without even loading an approach), it does not make sense but it’s a planning rule
3) On IAP approach, RAIM PREDICT will run automatically before FAF to show a final leg annunciation then RAIM FDE will run if it’s an RNP leg
I agree on 3) it is unnecessary (done by the box anyway before FAF) but I would carefully to check RAIM for 2), especially if STAR has 50nm or my if EAT changes: I think you will need to check RAIM even of not flying an RNP approach at destination as you expect to fly RNAV1…
Maybe this “tradition of mannual RAIM check during flight” comes from old days where no offline site was available? or when some approaches were designed with RNAV1 for final segment? will GPS run RAIM predict and actual magic before or after FAF on these @NCYankee?
Some examiners or instructors tells you to check RAIM on descent from cruise because 3) which I agree is not necessary but maybe it’s a mis-understanding of one way to comply with 2) or “legacy” reasons?
PS: you definitely need RAIM check during flight before DIY IAP on GPS, unless you code RNP0.3 leg in navigator yourself, everything will be on RNAV1 near destination without FDE 
If SBAS is available and box is TSO146: RAIM does not exit
RAIM is always running on most GPS navigators. The criteria changes based on the mode being used. Enroute, Terminal, or Approach. RAIM prediction is determining if RAIM will be able to run at a point in space and time based on the navigation mode.
Ibra wrote:
If SBAS is available and box is TSO146: RAIM does not exit
It does it exist and is used anytime outside an SBAS service volume or a failure of the SBAS system.
Yes that what I said SBAS signal AND TSO146 = NO RAIM
