Garmin G950 Tecnam 2006T - Manual (Page 333)

190-01146-00 Rev. A Garmin G950 Pilot’s Guide for the Tecnam P2006T
SY
STEM
O
VER
VIEW
FLIGHT
INSTRUMENTS
EIS
AUDIO P
ANEL
& CNS
FLIGHT
MANA
GEMENT
HAZARD
AV
OID
ANCE
AFCS
ADDITIONAL
FEA
TURES
APPENDICES
INDEX
321
APPENDIX D
FREqUENTLY ASkED qUESTIONS
If a particular aspect of G950 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
Waas?
The Wide Area Augmentation System (WAAS) 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 one of two geostationary satellites. This correction information can then
be received by any WAAS-enabled GPS receiver.
WAAS is designed to provide the additional accuracy, availability, and integrity necessary to enable users to
rely on GPS for all phases of flight. WAAS is currently available in the United States, including Alaska and
Hawaii.
h
oW Does
Waas
affect aPProach oPerations
?
Both LNAV/VNAV and LPV approaches use the accuracy of WAAS 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 WAAS. 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.
If WAAS is not available for the final approach course, the approach downgrades, as indicated by the “Approach
downgraded. Use LNAV minima.” message.
W
hat is
raiM
anD hoW Does it affect aPProach oPerations
?
When WAAS 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 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 prediction)
• Detect and exclude bad satellites from the navigation solution (Fault Detection and Exclusion, FDE)
RAIM ensures that satellite geometry allows for a navigation solution calculation within a specified protection
limit (4.0 nm for oceanic, 2.0 nm for enroute, 1.0 nm for terminal, and 0.3 nm for non-precision approaches).
Without WAAS or RAIM, GPS position accuracy integrity cannot be monitored.