from the selected course is conven-
5-
tional angular crosstrack deviation
expressed in degrees
off
course (one
dot equals
2").
In a VORlPAR mode, you have
in effect put the waypoint over the
VORTAC station and will, therefore, be
provided linear crosstrack deviation as
in
an
RNAV enroute mode. Remember,
VOR
and
DME information must be
provided
to
the
KNS
81
to
operate in
this mode.
Variations in along track
distance.
Under certain conditions, VOR
scalloping can contribute significant
variation in smoothness of the along
track distance while operating in the
RNAV modes.
VOR
scalloping is defined as'an
imperfection or deviation in the received
VOR signal that causes radials
to
devi-
ate from their standard track. VOR
scalloping is generally the result of
reflection from buildings or terrain. This
deviation or scalloping effect causes
the CDI needle
to
slowly or rapidly shift
from side
to
side.
loping include:
(1)
VOdAC location
in mountainous terrain when not a
Doppler VOR;
(2)
snow cover on the
ground around a VORTAC station.
Factors contributin
to
VOR scal-
The
effects
of
VOR
scalloping are minimized under the
followlng conditions:
1.
NT
2.
1
NT
3.
VORTAC
~
4.
m
WAYPOINT
5.
WAYPOl
NT
6.
When the waypoint offset distance is
Ion and the angle formed by the flight
small
(5)
(6).
(Note: When the angle is
large, the distance needs
to
be short.
Conversely, when the distance is long,
the angle needs
to
be
small. Another
way of saying this is that the along track
distance will have the least variation if
the geometry is such that DME infor-
mation is the major factor in computing
along track distance.)
pa
tf
and the waypoint
offset
radial is
11
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