FAA Instrument Flight Instructor (FII)IFR Procedures and ApproachesMedium
A pilot flying an RNAV (GPS) approach notices the equipment displays 'LNAV/VNAV' active but the LPV line of minimums is not being flown despite WAAS coverage in the area. What is the most likely explanation?
- AThe pilot must be receiving radar vectors to use LPV minimums
- BLPV minimums are only usable at towered airports
- CThe aircraft's WAAS receiver has lost the required integrity or vertical guidance for LPV service
- DLPV requires a barometric altimeter setting from the destination airport
Show answer & explanationAnswer & explanation
Correct answer: C. The aircraft's WAAS receiver has lost the required integrity or vertical guidance for LPV service
LPV (Localizer Performance with Vertical guidance) requires the WAAS receiver to have sufficient satellite geometry and integrity. If integrity or vertical accuracy is lost, the receiver automatically reverts to a lower level of service such as LNAV/VNAV or LNAV, even if WAAS coverage generally exists in the area.
Why the other options are wrong
- A. Radar vectors are unrelated to which line of minimums the receiver can display.
- B. LPV availability has nothing to do with whether the airport is towered.
- D. LPV uses WAAS-derived vertical guidance, not a local altimeter setting requirement, for eligibility.
LPV (Localizer Performance with Vertical Guidance)
A WAAS-based approach service providing precision-like vertical and lateral guidance; it requires sufficient WAAS integrity and satellite geometry, and automatically downgrades to LNAV/VNAV or LNAV if not available.
- Requires WAAS-capable GPS receiver
- Provides ILS-like minimums without ground equipment
- Automatically reverts to lower service if integrity is lost
- Charted as its own line of minimums on RNAV approach plates
Memory trick: LPV needs a 'Locked-in Precise View' from satellites — lose it, drop a level