Differences between WAAS and non-WAAS gps are shown in the chart below.
| System: | non-WAAS gps | WAAS gps |
|---|---|---|
| Certification basis | TSO-C129() or TSO-C196() | TSO−C145() or TSO−C146() |
| Permitted uses | As per FAA-approved aircraft flight manual (AFM) or flight manual supplement. | As per FAA-approved aircraft flight manual (AFM) or flight manual supplement. |
| RNAV approach types available | LNAV | LPV, LNAV/VNAV, LP (some systems), and LNAV |
| Required pre-flight checks | RAIM, GPS Notams, database checks | WAAS Notams, GPS Notams, database checks |
| Means of IFR navigation | Secondary. Must be equipped with an alternate approved and operational means of navigation suitable for navigating the proposed route of flight. Active monitoring of alternative navigation equipment is not required when RAIM is available for integrity monitoring. Active monitoring of an alternate means of navigation is required when the GPS RAIM capability is lost. | Primary. Does not need additional means of navigation |
| Flight planning limits |
Pilots may file based on a GPS-based IAP at either the destination or the alternate airport, but not at both locations. At the alternate airport, pilots may plan for: a) Lateral navigation (LNAV) or circling minimum descent altitude (MDA) b) LNAV/vertical navigation (LNAV/VNAV) DA, if equipped with and using approved barometric vertical navigation (baro-VNAV) equipment c) RNP 0.3 DA on an RNAV (RNP) IAP, if they are specifically authorized users using approved baro-VNAV equipment and the pilot has verified required navigation performance (RNP) availability through an approved prediction program If the above conditions cannot be met, any required alternate airport must have an approved instrument approach procedure other than GPS-based that is anticipated to be operational and available at the estimated time of arrival, and which the aircraft is equipped to fly. |
Pilots with WAAS receivers may flight plan to use any instrument approach procedure authorized for use with their WAAS avionics as the planned approach at a required alternate, with the following restrictions. When using WAAS at an alternate airport, flight planning must be based on flying the RNAV (GPS) LNAV or circling minima line, or minima on a GPS approach procedure, or conventional approach procedure with “or GPS” in the title. |