FAA Aircraft Dispatcher (ADX)Navigation and ATCMedium
An aircraft is conducting an RNAV (GPS) approach and the approach chart displays LPV minimums. What does LPV rely on to provide vertical guidance comparable to an ILS glideslope?
- ASatellite-based augmentation system (SBAS) signals such as WAAS
- BA DME-derived descent profile calculated by the aircraft's FMS
- CA ground-based glide slope transmitter co-located with the localizer antenna
- DBarometric vertical navigation computed solely from static pressure
Show answer & explanationAnswer & explanation
Correct answer: A. Satellite-based augmentation system (SBAS) signals such as WAAS
LPV (Localizer Performance with Vertical guidance) minimums use SBAS, such as WAAS in the U.S., to provide angular lateral and vertical guidance similar to an ILS, without requiring ground-based glide slope equipment.
Why the other options are wrong
- B. DME-based descent profiles are unrelated to how LPV vertical guidance is generated.
- C. LPV does not use a ground glide slope transmitter; it's satellite-based.
- D. Baro-VNAV provides vertical guidance but is a separate line of minima (LNAV/VNAV), not LPV.
LPV Approach Minimums
LPV minimums use WAAS (a form of SBAS) to provide precision-like lateral and vertical guidance on an RNAV (GPS) approach, achieving ILS-like decision altitudes without ground-based glide slope equipment.
- Requires WAAS-enabled GPS receiver
- Provides angular guidance similar to ILS glideslope
- Distinct from LNAV/VNAV, which may use baro-VNAV
- Can achieve DA as low as 200 ft in some cases
Memory trick: 'LPV Loves Satellites' — WAAS in the sky replaces the glide slope on the ground.