piontyendforward,
I thought the 737 does have RAIM, just not predictive RAIM. You can get predictive RAIM at dispatch time with Wx and Notams.
Thought the GPSSU provides GPS position integrity to the FMC by GPS RAIM. RAIM computes an actual containment radius/horizontal integrity limit that is a function of the actual detected error in the GPS position. For RNP 0.3 the FMC uses GPS RAIM, to see if it has the required RNP, if it doesn't you get a "UNABLE RNP" message.
Cannot do RNP 0.3 without GPS and 2xFMC, and at least 2xIRS.
I dont belive the GPS on the 737 meet sole means of navigation, but does meet primary means down to RNP 1.0 in most latitudes (higher latitudes generally have fewer satellites avaiable), and supplementary means for less than RNP 1.0.
Airbus have predictive RAIM +/- 15 minutes for the FMC destination and calculated arrival time with an option for another destination and arrival time. Its just a function of FMC software, nothing to with capability of either aircraft, in some cases its the same FMC manufacturer in both aircraft.
The 737 has better LNAV/VNAV display when flying RNP approaches, with the horizontal and vertical RNP scale shown on the PFD, the 737 has the G/S ghoast pointer, airbus has the doughnut, both have a vertical deviation scale on the PFD, the airbus doesnt have lateral deviation on the PFD, just the ND in FINAL APP.
Personally prefer the airbus GPS position monitor page over the B737 as it serves as a backup in the event of unreliable airspeed from the ADC and/or IRS, most probable never use it in my career in anger, just nice to have real time ground speed, track, and GPS altitude available from another source.
