NEXTGEN AVIONICS (Next Generation Air Transportation System)
NextGen is the 21st century's new satellite navigation and digital communication technology which will eventually replace all the old 1940's ground based technology of surveillance and navigation which we use today.
It will become operational in the next 5 years, and be nationwide by 2025. It is not clear yet as to how much airspace access will be available to aircraft that do not have NextGen avionics when the system is completely up and running, however with about 15 years before that happens, it is fairly certain that most pilots will do some kind of upgrading of their equipment before then, so the real issue is how to make certain that you are purchasing equipment that will be appropriate for the transition to NextGen.
The basis for NextGen is an increased performance level over previous equipment, for example in an IFR situation, the NextGen equipment is required to provide positional accuracy to within 0.3 nautical miles. The latest GPS units with WAAS (Wide Area Augmentation System) achieve better than this accuracy, so they would be a logical option to consider in the upgrade scenario.
As a VFR pilot you could think about either a handheld system, or a traditional panel mount. Handheld systems are not approved for IFR, so if that is your flying, you will have to go with a panel mounted unit.
Panel mounted GPS/WAAS units are covered by two TSO's (Technical Service Orders). TSO-C145a is Airborne Navigation using the WAAS, and TSO-C146a is Stand Alone Airborne Navigation using WAAS. The latter is the better option as it certifies GPS/WAAS as the primary source of navigation, and therefore replaces VOR's.
ADS-B (Automatic Dependent Surveillance-Broadcast ) will replace radar and ultimately your transponder. It is expected to be running nationwide by 2013. By utilizing 794 ground based transceivers the ADS-B system will send out GPS/WAAS information to Air Traffic Control, and also to any aircraft equipped to receive and display the information. Traffic (TIS-B) and weather (FIS-B) can and will be displayed on appropriate cockpit display equipment.
ADS-B is a 2 box system, and although the rule making process is not completely finalized, it seems that you will need box 1; a Universal Access Transceiver (UAT) for all flights under FL240, and for operations over FL240 you will need that same UAT, plus box 2; a 1090 ES (1090 is the transmit frequency, and ES is Extended Squitter- a Mode S signal)
Most of the ADS-B display interfaces are currently linked to panel mounted Multi-Function Displays (MFD's), but there are several handheld GPS/WAAS units that will display the UAT data, overlaying onto internal database information.
GPS/WAAS Instrument Approaches
LNAV: Lateral navigation is the name given to a non-precision GPS approach. No vertical guidance with a minimum descent altitude (MDA) just as a conventional non-precision approach. Typical figures for an LNAV MDA is 400ft above the runway.
LNAV/VNAV: Lateral navigation/vertical navigation. Approach information is provided by an approved GPS/WAAS, and with electronic glidepath the decision altitude is usually 350ft above the runway.
LPV: Localizer performance with vertical guidance is a new approach requiring an approved WAAS unit. More precise than LNAV/VNAV, LPV is the equivalent of a Category 1 ILS approach, and has a decision altitude between 200 and 250ft above the runway.