Sorry guys but I have another question!
Are the RAIM predictions issued by airservices (below) based on a 2-D or a 3-D navigation solution?
[attachment=1044]RAIM.PNG[/attachment]
Ignoring Baro-aiding, for a 2-D nav solution, the GPS requires
[ul]
[li]3 sats for a nav solution[/li]
[li]4 sats for RAIM FD[/li]
[li]5 sats for RAIM FDE[/li]
[/ul]
For a 3-D nav solution add one extra sat.
[ul]
[li]4 sats for a nav solution[/li]
[li]5 sats for RAIM FD[/li]
[li]6 sats for RAIM FDE[/li]
[/ul]
Now given that all RNAV[sub](GNSS)[/sub] approaches in Australia are 2-D approaches, RAIM predictions based on a 3-D approach would be unduly restrictive. Does anyone have any thoughts on this?
The answer to this question may affect the answer to Q7 on page 106 below.
[attachment=1047]RAIMQ7.PNG[/attachment]
We have been researching this and have been unable to find a specific reference. However the implication would surely be that since RNAV 3D approaches are still in the developmental stage and are only available with special approval, the current RAIM prediction service is based on the 2D approach criteria. This paragraph from CAAP 179a indicates that.
[attachment=1048]CAAP 179a.png[/attachment]
