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B KLN 94
Rev. 4, Jan/2003 10599I04.CDL Page 2-83
TABLE 2-2 GPS PAGE MESSAGES
GPS Page
Messages
Definition Suggested Action
RAIM not available
Cross check position
This means there are not enough
satellites available to compute
integrity (RAIM).
1. The satellites are blocked from
view by obstructions.
2. The satellites are too low on the
horizon for use or too high for
adequate geometry.
3. There is a loss of sensitivity in
the antenna, the coax or receiver
module.
The aircraft should be in an open area with good
visibility and the SNR (Signal to Noise Ratio) on the
AUX 2 page should be:
A KLN 94 will usually have 6-8 satellites shown and
the majority of their SNR values will be 7 to 9. SNR
values of 3 and below are unusable, 4 is marginal
and 5-9 are considered good.
If the SNR values are low, it could be one of the
following, in order of probability:
1. Check the antenna coax and connection for
problems.
2. Verify that 5 volts is present at the antenna end
of the coax.
3. Substitute the receiver to check for sensitivity.
4. Substitute the antenna to check for sensitivity.
RAIM not available
Approach mode
inhibited
Predict RAIM on AUX
3
This is a calculated prediction of
RAIM availability. The message
appears when integrity monitoring
(RAIM) is predicted to not be
available at either the FAF or MAP.
The GPS will not allow the unit to
go into APR ACTV mode until
conditions improve.
This is a feature, not a system failure.
Turn to the AUX 3 page to perform a RAIM
prediction. It will give you an indication of how long
it will be until RAIM is available.
This prediction can also be performed prior to
departure to insure RAIM at your arrival.