190-00709-05 Rev. D
Garmin G1000 Pilot’s Guide for the Socata TBM 850/900
693
APPENDIX D
FREQUENTLY ASKED QUESTIONS
If a particular aspect of G1000 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.
W
hat
is
sBas?
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.
h
OW
DOes
sBas
aFFect
aPPROach
OPeRatiOns
?
LNAV/VNAV, LP, and LPV RNAV 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 RNAV LP and LPV approaches further improves precision approach capabilities.
RNAV LPV approaches are designed to make full use of the improved GPS signal from the SBAS. This approach
combines localizer precision lateral guidance with vertical guidance similar to the typical Instrument Landing
System (ILS). RNAV LPV approaches allow lower approach minimums.
W
hat
is
Raim
anD
hOW
DOes
it
aFFect
aPPROach
OPeRatiOns
?
When SBAS is unavailable, the GPS receivers use Receiver Autonomous Integrity Monitoring (RAIM) to
perform the following functions:
• Monitor and verify integrity and geometry of tracked GPS satellites
• Notify pilot when satellite conditions do not provide the necessary coverage to support a certain phase of
flight
• Predict satellite coverage of a destination area to determine whether the number of available satellites is
sufficient to satisfy requirements (refer to the System Overview Section for instructions on RAIM prediciton)
• Detect and exclude bad satellites from the navigation solution (Fault Detection and Exclusion, FDE)
NOTE
:
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.
