GPS (GNSS-RNAV) approach training
Flying a GPS approach requires associated skills and knowledge. The FAA regulations are not too demanding, however a GPS approach should not be conducted without the specific knowledge and training (if the behavior of the avionics is unclear in flight, the User Guide will be of no help!).
A GPS approach does not fundamentally differ from an ground based aid approach, VOR, LOC or ILS. However there are a number of points to be taken into account to comply with the regulation and guaranty safety. Somes examples:
- Rules regarding the destination and alternate airports;
- Sensitivity of the CDI according to the present GPS mode: en-route, terminal, approach, direct-to (a half-deviation of the CDI indicates an offset from the selected axis of 280 to 4500 m depending on the mode!);
- Update of the database;
- Alternate action plan;
- Availability of the signals (RAIM);
- Availability of procedures;
- Availability of the required fixes in the GPS flight plan. For example, it happens that the PN406 fix of the GPS approach at Toussus does not appear on display, why? How to retrieve it? Is it recommanded and safe to select a ‘direct-to’ PN406?
- Type of final approach, CDFA vs non-CDFA;
- Pilot action required in case of missed approach (without specific action, the GNS 430-GNS 530 will not sequence the missed approach fixes);
- The pitfalls of overlay approaches;
All these points, and others, can be discussed in a 3-hour briefing (with PPS-like slides) and 2 hours on simulator (see precision of the simulator).
The simulator training can be supplemented or replaced by a flight on your own aircraft with the avionics to which you are accustomed.
If you are not familiar with the GPS approach or if the acronyms like LNAV, VNAV, LPV, BARO, FPA, CFDA, RAIM are unclear, then this training is essential for the safety.