RNP APCH with LPV/LP Minima

What it is

Requires its own AMMS option file enabled. RNP approaches flown to LPV or LP minima (charted as RNAV(GPS) or RNAV(GNSS)) use Satellite Based Augmentation (SBAS) to fly an approach with vertical guidance down to a 200 ft decision height, with no airport-specific ground equipment required. LPV gives lateral and vertical angular guidance; LP gives lateral angular guidance paired with Baro-VNAV for the vertical path instead. The GNSS sensors feed the FMS pseudo-localizer (NLOC) and pseudo-glideslope (NGS) deviations that the AFCS actually couples to.

Approved for day/night VFR and IFR. Maximum glide path angle 9°. Minimum airspeed to engage APP mode for these minima is 45 KIAS, and AFCS IAS mode must be engaged below 50 KIAS. Maximum ROD approaching the missed approach point is 900 fpm. Maximum airspeed at DH is 130 KIAS below 5000 ft, reducing 2 kt per 1000 ft above that — and if PWR LIM illuminates on the way down, airspeed must be reduced enough to clear it before reaching DH.

The annunciation colors

White: the LP or LPV approach loaded correctly and the path is computed with no GNSS failure. Green: the pseudo-localizer deviation has been captured. Amber: a single or dual GNSS sensor used for the approach is degraded or has failed. These are worth reading correctly in real time, since the malfunction procedures below hinge on exactly this annunciation.

Flying it

Before the FAF: confirm the white LPV or LP advisory, DA(H) set per the approach chart, PERFINIT executed, VNAV phase at CRUISE before the vertical path capture, and TOD correctly computed and shown. Arm NAPP (and NDCL if a deceleration profile is used) on the AFCS panel. If above the FAF altitude, the FMS captures the vertical path in Baro-VNAV down to FAF altitude, then transitions to pseudo-LOC/pseudo-GS guidance inside 2 NM of the FAF.

During final approach: once APP shows green, confirm the LPV or LP annunciation is also green, with the lateral axis transitioning automatically from NAPP to NLOC, and NGS engaged. A missed approach couples automatically on the lateral axis when GA is pressed — the vertical profile still has to be flown manually per the published missed approach altitudes.

What a GNSS problem actually costs you

A single GNSS RAIM integrity failure, or one SBAS precision-approach channel going to standby, just means continue the approach — redundancy is reduced, not lost (SBAS integrity re-checks every 4 seconds and can recover on its own).

If SBAS precision mode is lost on both GNSS sensors at once, the outcome depends on whether Baro-VNAV minima are available for that approach. If they are, FMS deviations revert automatically to LNAV/VNAV and Baro-VNAV — LPV is replaced by VGP on the PFD — and the approach can continue in coupled mode by pressing APP or DCL again, unless the aircraft is already below 1000 ft AGL, in which case discontinue regardless. If Baro-VNAV minima are not available at all, there's no fallback — discontinue the approach outright.