FAA Instrument Rating Airplane (IRA)Navigation SystemsEasy
A pilot is flying an RNAV (GPS) approach. The aircraft's GPS receiver has WAAS capability. What is the highest level of service and associated minima that can typically be used with a WAAS-enabled GPS?
- ALPV (Localizer Performance with Vertical Guidance), allowing for precision-like minima.
- BRNP 0.1, requiring specialized aircraft equipment.
- CLNAV only, due to the inherent limitations of GPS.
- DLNAV/VNAV, providing limited vertical guidance.
Show answer & explanationAnswer & explanation
Correct answer: A. LPV (Localizer Performance with Vertical Guidance), allowing for precision-like minima.
WAAS (Wide Area Augmentation System) significantly enhances the accuracy, integrity, and availability of GPS signals, enabling the highest level of RNAV (GPS) approach service: LPV (Localizer Performance with Vertical Guidance). LPV approaches provide precision-like vertical and lateral guidance, often with minima comparable to Category I ILS.
Why the other options are wrong
- B. RNP 0.1 is a very high performance level, typically for specialized RNP AR approaches, not the general highest level for WAAS-enabled GPS approaches without additional certification.
- C. LNAV is the lowest service level; WAAS allows for much higher precision.
- D. LNAV/VNAV is a higher level than LNAV, but LPV is the highest for WAAS-enabled approaches.
WAAS Enabled GPS Approach Capability
WAAS significantly improves GPS accuracy and integrity, enabling LPV (Localizer Performance with Vertical Guidance) approaches, which offer precision-like guidance and minima comparable to ILS Cat I.
- Enhances GPS accuracy, integrity, availability.
- Enables LPV approaches.
- LPV provides precision-like guidance.
- Minima comparable to Cat I ILS.
Memory trick: WAAS: Works Always, Allows LPV, Achieves Precision.