WAAS is SBAS. SBAS is the overarching name for the various regional systems.
WAAS is the US SBAS system, there's others as well like EGNOS in Europe, GAGAN in India, MSAS in Japan, SDCM in Russia. China are bringing one on line too I think.
Interestingly Australia and New Zealand are about the only two places in the world outside of Africa and South America that don't have an SBAS system or at least an SBAS system in development. I hear there is a push at the moment to get a system in this part of the world. Not before time if you ask me.
RNP doesn't require any augmentation systems like GBAS or SBAS.
As I understand it under PBN, RNP ops require on board integrity monitoring systems i.e. RAIM and allow ops outside of controlled (radar) airspace whereas RNAV ops don't require on board integrity monitoring and are therefore conducted inside controlled airspace, the integrity being provided by the radar controller.
Both RNP and RNAV ops can use a variety of nav sensors to calculate the nav solution. i.e. INS, VOR/DME, DME/DME, GNSS.
The plate will either say LNAV for just lateral guidance, or VNAV for vertical guidance. Baro VNAV is another option using a baromertic input to the nav computer to give vertical guidance, this is pretty well only available on the like of an FMS system and not available for pure GNSS ops.
The plate labeling (i.e. LNAV or VNAV)will be beside the minima info for that approach.
If you're looking at a GNSS approach without the availablity of SBAS it's very unlikely there'll be any reference to VNAV, there might be a Baro VNAV option.
Then you have RNP AR approaches which do have curved segments and vertical guidance, but they're only available to operators who have approval (hence the AR tag). Right gear on board the aircraft with appropriate crew training.
Last edited by 27/09; 20th Sep 2014 at 23:56.