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					For more information                  DME ARC with                       NEVER GET LOST
www.nevergetlost.at                  STANDARD–VOR


Intercepting the ARC
The DME arc is intercepted while flying towards or away from a VORTAC or VOR/DME
station. Usually a 90° turn is required to intercept a DME arc.
Avoid an over- or undershooting of the DME arc. The point of starting the turn (Lead Point)
has to be plotted according to the ground speed. A standard turn has to be maintained.
With a ground speed of less than 150 KT, 1NM will do. The curve diameter is about 1% of
the TAS, for example: 160 KT would be 1,6 NM.
Before crossing the Lead Point make sure the direction of the turn and the heading is
plotted for the roll out. During the turn the pilot has to maintain the CDI needle of the VOR
in the center. If the CDI is centered and the heading on the VOR indicates an abeam
position: level out. If the DME distance is too short, turn to a heading which is indicated in
the lower part of the VOR instrument. Again this applies only if the CDI is centered. While
following a heading from the lower part of the VOR instrument, the plane will fly away from
station. The DME distance will increase since the plane flies away from the station.
If the DME distance is too big, turn to a heading which is indicated in the upper part of the
VOR instrument. The DME distance will decrease, since the plane flies towards the
station.
If a heading is followed which shows on the VOR an abeam position, the DME indicating
will not change. Again this applies only if the CDI is centered. But if a heading from the
upper part of the VOR instrument is maintained, the plane will soon overshoot the required
track. The indicated distance will increase. The CDI is maintained in the center by
constantly setting the OBS.




The DME distance remains         The     DME        distance    The    DME         distance
the same.                        increases.                     decreases.


     D 15 ARC




Lead Point D 17,0 ORI            The heading 090 points         The heading 070 points
Make a banking turn at 17        below abeam.                   above abeam.
DME tracking the ARC. see        The     DME   indicating       The    DME    indicating
page 115.                        increases.                     decreases.
For more information               DME ARC with                      NEVER GET LOST
www.nevergetlost.at               STANDARD–VOR


                                            ♦ all rules apply only if the CDI is fairly
                                              centered.
                                            ♦ the airplane flies a heading rate which
                                              is indicated in the lower part of the VOR
                                              indicator. The distance to the station
                                              will increase.
                                            ♦ see illustration on the left, heading 110.




                                            ♦ all rules apply only if the CDI is fairly
                                              centered.
                                            ♦ the airplane flies a heading rate which
                                              is indicated in the upper part of the
                                              VOR indicator. The distance to the
                                              station will decrease.
                                            ♦ if the airplane follows a heading rate
                                              which is indicated in the upper part of
                                              the VOR instrument, the distance to the
                                              station will decrease.
                                            ♦ see illustration on the left, heading 060.




Maintaining the arc
Arcs with larger radii are easier to fly due to their “flat” curve, than arcs with short
distances.
The higher the GS, the sooner a corrective change in heading has to be made.
Theoretically a DME arc is flown by keeping the heading constantly in the abeam position
shown on the VOR indicator. But in practice the DME arc consists of short and straight
legs. If the airplane maintains exactly the required distance and a heading is followed
which value is shown on the VOR in exact abeam position, maintain this heading until the
heading on the VOR will indicate 5° to 10° “below” abeam. The DME distance will increase
slowly.
The next step obtains a corrective change in course towards a heading, shown on the
upper part of the VOR instrument. The CDI has to be fairly centered by setting the OBS
constantly. Maintain the correction as long as the heading on the VOR points 10° “above”
abeam. Whenever a heading corresponds in the value, which is on the VOR indicator
above abeam, the DME distance will decrease. This is the procedure of flying a DME arc.
For more information             DME ARC with                     NEVER GET LOST
www.nevergetlost.at             STANDARD–VOR



               Radial
               090




                           ♦ The airplane is located at radial 180.
                           ♦ The airplane flies a 090° heading, which stands in exact
                             abeam position on the VOR indicator.
                           ♦ For the time being the DME distance will remain the
                             same, later on the DME distance will increase.




                  Radial
                  090




                           ♦ The airplane is located at radial 170.
                           ♦ The airplane flies a 090° heading, which stands in the
                             lower part on the VOR indicator.
                           ♦ From now on the DME distance will increase, first slowly
                             then faster.
For more information                 DME ARC with                       NEVER GET LOST
www.nevergetlost.at                 STANDARD–VOR




                     Radial
                     090




                               ♦ The airplane is located at radial 104.
                               ♦ The airplane flies a 315° heading, which stands 30° to
                                 the right on the VOR.
                               ♦ The difference to radial 090 amounts only to 14°.
                               ♦ From now on the inbound is intercepted with an angle
                                 of 30 degrees.




Intercepting a radial or a localizer
There is no big difference if a desired course is approached via a DME arc or via a straight
leg. About 20° before tracking the desired course make a banking turn to a 45°
interception heading. Normally with a 45° angle a localizer can be intercepted easily.
In most cases the “LEAD RADIAL” is given by the IAL (Instrument Approach and Landing
Chart)

                                 If an airplane is located at radial 115, make a left turn.
                                 The 45° interception heading would be then 331°. The
                                 localizer is going to be intercepted by a 45° angle.
                                 If the TAS is above 160 KT the localizer should be
                                 intercepted by a 30° angle. The interception heading is
                                 going to be then 316°.




                                     Lead Radial


Attention: If the Lead Radial is missed you will overshoot the required inbound track.
Make sure you apply immediately the necessary corrections otherwise the airplane is
going to be located outside of the controlled area, which provides obstacle free clearance.
One flies outbound with a 90° angle!

				
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