Garmin Flight Deck 100 User Manual

190-00728-04  Rev. A

657

If a particular aspect of system operational capability is not addressed by these commonly asked questions or in 

the index, contact Garmin (see the copyright page or back cover for contact information) or a Garmin-authorized 
dealer.  Garmin is dedicated to supporting its products and customers.

The Satellite Based Augmentation System (SBAS) uses a system of ground stations to correct any GPS signal 

errors.  These ground stations correct for errors caused by ionospheric disturbances, timing, and satellite 
orbit errors.  It also provides vital integrity information regarding the health of each GPS satellite.  The signal 
correction is then broadcast through geostationary satellites.  This correction information can then be received 
by any SBAS-enabled GPS receiver.

SBAS is designed to provide the additional accuracy, availability, and integrity necessary to enable users to rely 

on GPS for all phases of flight.

There are several SBAS systems serving different parts of the world.  The Wide Area Augmentation System 

(WAAS) is currently available in the United States, including Alaska and Hawaii.  The European Geostationary 
Navigation Overlay Service (EGNOS) offers coverage of Europe, parts of the middle east and northern Africa.  The 
Multi-functional Satellite Augmentation System (MSAS) covers mainly Japan and parts of northern Australia. 

Both LNAV/VNAV and LPV approaches use the accuracy of SBAS to include vertical (glide path) guidance 

capability.  The additional accuracy and vertical guidance capability allows improved instrument approaches to 
an expanded number of airports throughout the U.S.

The implementation of LPV approaches further improves precision approach capabilities.  LPV approaches 

are designed to make full use of the improved GPS signal from the SBAS. This approach combines the LNAV/
VNAV vertical accuracy with lateral guidance similar to the typical Instrument Landing System (ILS).  LPV 
approaches allow lower approach minimums.

RAIM is an acronym for Receiver Autonomous Integrity Monitoring.  RAIM is a GPS receiver function that 

performs the following functions:

• Monitors and verifies integrity and geometry of tracked GPS satellites

• Notifies the pilot when satellite conditions do not provide the necessary coverage to support a certain phase

of flight

• Predicts satellite coverage of a destination area to determine whether the number of available satellites is

sufficient to satisfy requirements

If RAIM is not predicted to be available for the final approach course, the approach does not become  

active, as indicated by the “RAIM not available from FAF to MAP” message and the LOI annunciation 
flagging on the HSI.