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6-20
The destination waypoint will, by default, be the missed
approach point of an approach loaded in the flight plan. If
there is no approach in the flight plan, then the default
waypoint is the last waypoint in the active flight plan. Of
course it is possible for you to enter any waypoint in this
field.
The time used for the RAIM prediction will be the current
ETA to the destination airport or the MAP. This time is
automatically updated by the KLN 90B so there is usually
no need to enter a value. If you are making a RAIM calcu-
lation for planning purposes, it is also possible to enter a
time in this field. An important point about this time is that
the time used for RAIM prediction is always in the future
and limited to 24 hours from the present time. For
example, if the time is now 19:30 and the time entered for
the ETA is 18:30, then the prediction will be made for the
next day not one hour ago.
To perform a manual RAIM calculation use the following
procedure.
1. Turn the left outer and inner knobs to select the STA
5 page.
2. Press the left C. The cursor will be over the DEST
field.
3. Enter the desired waypoint identifier by using the left
inner and outer knobs just like you do for any other
waypoint entry.
4. Once the desired waypoint identifier is entered press
E (figure 6-29). Press E again if the waypoint
information is correct.
5. The cursor will now be over the ETA field. Use the left
inner knob to enter the desired hour. Note that the
current time zone is displayed below the ETA field. Use
the left outer knob to move the cursor over the minutes
field. Use the inner and outer knobs to select tens of min-
utes and single minutes as required. When the desired
time is selected press E. The RAIM calculations will
start.
6. The RAIM calculation will usually take a few seconds
before an answer is reached. During this time the STA 5
page will be as shown in figure 6-30.
7. Once the RAIM calculation is complete, the STA 5
page will indicate the results of the test. This is done
graphically in a bar graph format. The center of the bar
graph represents the ETA that you entered in step 5.
Each bar represents 5 minutes of time. The RAIM
calculation is good for ±15 minutes of the ETA. Bars that
are above the line indicate that RAIM is available and
bars below the line indicate when RAIM is not available.
An example is shown in figure 6-31. Notice in the figure
that the first four bars are below the line and the other
three are above the line. This means that RAIM is not
available at the ETA, nor during the 15 minutes prior to
the ETA. RAIM is predicted to be available five minutes
after the ETA and the next 10 minutes. By showing the
times when RAIM will be available it is possible for you to
alter your ETA to ensure that there will not be any RAIM
problems.
Even more rare will be the case when the KLN 90B
cannot provide sufficient integrity monitoring or if there is
an actual satellite failure while the aircraft is on the leg
from the FAF to the MAP. In these cases the KLN 90B
will FLAG the navigation solution and a missed approach
will have to be flown. The KLN 90B will provide the
following message:
PRESS GPS APR FOR NAV
This message is telling you to cancel the approach mode
by pressing the external switch/annunciator. This will
change the unit to the approach-arm mode and
navigation information will be restored.
Rev 1
Figure 6-29
RAIM STATUS|
DEST: 3K1 |
ETA: 14:35|
CST|
COMPUTING |
-15 0 +15|
STA 5|
Figure 6-30
RAIM STATUS|
DEST: 3K1 |
ETA: 14:35|
CST|
èèèèééé |
-15 0 +15|
STA 5|
Figure 6-31
RAIM STATUS| 3K1
DEST: 3K1 |ALVA MUN
ETA: --:--|
CST|
êêêêêêê |N 36^46.39'
-15 0 +15|W 98^40.20'
CRSR| ent|APT 1