Oh go on then.
Gps approach = Approach using GPS satellites position updating (uses the USA System of Global Positioning Satellites) Now being phased out and replaced by RNP APRCH
Gnss approach = Approach using Global Navigation Satellite System (can use present GPS and the new European Galileo Sat Nav System of the future) (eg GNSS APP LGW 26L required accuracy = 0.3nm)don't forget the Russian, Chinese and indian systems and see note above
Rnp approach = Area Nav Approach using DME/DME, VOR/DME, or Satellite system for position updating with a position accuracy of "X". (X is usually 1 nm)Includes RNP approach procedures and RNAV (GNSS-based) approach procedures designed with a straight segment, the accuracy normally being 0.3.
GNSS is the primary navigation service that supports RNP APCH procedures. The acceptability of the risk of loss of RNP APCH capability due to satellite failure or loss of onboard monitoring and alerting function must be considered during procedure design.
The missed-approach segment may be based on RNAV or conventional navigation procedure.
RNP APCH navigation specification does not include specific requirements for communication or surveillance.
Rnav approach = Area Nav Approach as above - but not necessarily to the same required accuracyObsolete term now being replaced by RNP
Rnp ar approach = Not certain - think it might be the Arrival Procedure leading to the RNAV Approach.An RNP approach procedure featuring special aircraft aircrew and approach procedure authorization by the regulatory authorities.
It normally applies to airports where there is complex terrain and limited airspace and requires accuracy normally between 0.3 and 0.1.
Only GNSS is the allowed to be the navigation source and achievable actual RNP precision shall be predicted.
The specification excludes specific communication and surveillance requirements.