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6-16
6.1.8 Example Approach: DME Arc
DME arc procedures with the KLN 90B are completely
different from using traditional VOR and DME equipment.
Don’t worry though because DME arc procedures using
the KLN 90B are also easier than using traditional equip-
ment. This is because the KLN 90B provides left/right
guidance around the arc. No more having to watch dis-
tance in one place and radial in another!
A DME arc is really a whole bunch of initial approach
fixes placed one next to each other to form an arc. Very
rarely do you actually fly to the beginning of an arc.
Instead, the flight path of the aircraft generally intersects
the arc at some point. Once the aircraft is near the arc, it
is then possible to turn so that the arc distance is main-
tained until time to turn to the inbound fix.
The following example will show how DME arc proce-
dures are flown using the KLN 90B. This example
approach will be to use the VOR RWY 12 approach to
Owatonna, Minnesota, KOWA. The approach plate for
this approach is in figure 6-23. Assume that the aircraft is
approaching from the North.
1. ATC assigns the VOR RWY 12 approach. Turn to
the APT 8 page for KOWA to select the approach. You
select the VOR 12 approach and the KLN 90B presents
the IAF selection page (figure 6-24).
2. There are five choices for the IAF. Three of these
choices you can recognize but the other two, D040L and
D220L, are unfamiliar and not shown on this chart.
These two waypoints are the database identifiers for the
ends of the arc. D040L means DME arc point, 040 is the
radial which the waypoint lies, and L indicates the dis-
tance of the arc. L is the twelfth letter of the alphabet so
the L indicates that this is a 12 DME arc. In a similar
manner D220L can also be decoded. In this example the
aircraft is approaching from the north so the D040L IAF
will be selected.
3. The KLN 90B knows that this point is associated with
a DME arc. Once an arc waypoint is chosen, the KLN
90B determines what radial of the reference VOR the air-
craft is presently located on. A waypoint is created that is
located at the intersection of the present radial and the
DME arc. This waypoint is the first waypoint in the list of
waypoints presented on the APT 8 page before loading
the approach into the flight plan (figure 6-25). This way-
point is named using the same convention discussed
earlier.
NOTE: If the present radial from the reference VOR is
outside of the defined arc, then the KLN 90B will default
to the beginning of the arc.
CAUTION: The KLN 90B does not take into account
the geometry of the active flight plan when determin-
ing the arc intercept point. This point is defined
Rev 1
Figure 6-24
|V12-KOWA
| 1 D011Lì
| 2 D310L
| 3 FOWî
| 7 FOWï
|LOAD IN FPL
ent CRSR
Figure 6-25
|V12-KOWA
|IAF 1 ALMAY
| 2 D040L
| 3 D220L
| 4 FOW
| 5 MKT
ent CRSR
Figure 6-23