It is TSO 129, the minimum level for RNAV enroute, terminal and approach capability. You can fly RNAV GNSS approaches with some really old TSO 129 gear including Garmin 155 and 300XL models.
I believe you need two TSO 145/6 units to enable sole means navigation.
GNS 530(A) Pilot’s Guide and Reference
190-00181-00 Rev. H
1-5
SECTION 1
INTRODUCTION
1.3 TAKEOFF TOUR
Overview
The Garmin GNS 530 provides the pilot accurate
navigational data and communication capability, along
with non-precision and precision approach certification
in the IFR environment. The takeoff tour is designed to
familiarize the pilot with:
Last edited by Two_dogs; 12th Apr 2014 at 05:35.