(2011) Service Advisory 1141 Rev A: Garmin SBAS-capable receivers may experience loss of LPV or LNAV/VNAV capability due to incoherent EGNOS satellite GEO ranging data

AFFECTED PRODUCTS

G1000, G1000H, G950, G900X, G500, G500H, G600, Cirrus Perspective™, and Embraer Prodigy® integrated flight deck systems, GPS 400W, GNC 420W, GNS 430W, GPS 500W, GNS 530W, GNS 480 (CNX80), and GTN 625/GTN 635/GTN 650/GTN 725/GTN 750 navigation systems using EGNOS to conduct satellite-based augmentation system (SBAS) required terminal operations are affected.

PURPOSE

Refer to EASA Safety Information Bulletin (SIB) No. 2011-24. EGNOS satellites occasionally transmit incoherent data in the geo ranging messages. When incoherent EGNOS satellite GEO ranging message data is received by a Garmin SBAS-capable receiver there is no impact in the accuracy or integrity of the position determination; however, a loss of vertical guidance for the RNAV (GPS) approach may occur.

PILOT ACTION

Loss of vertical guidance during an LPV or LNAV/VNAV approach will cause the receiver to annunciate that the approach has been downgraded to an LNAV approach for the selected runway and the pilot is to use LNAV minima. If an LNAV approach is not available, the pilot must execute the published missed approach procedure. When planning flights to aerodromes with LPV or LNAV/VNAV approaches, always ensure
availability of required contingency procedures.