King Air C90GTi, Pilot Training Manual

Page: 381 / 557

Once an altitude restriction is inserted either
automatically or manually, the FMS will gen-
erate the associated glidepath. The glidepath
will be displayed at the appropriate point. As
long as the proper conditions are met, the FGS
will capture and track the vertical glidepath.
The conditions are as follows:
• The altitude must be entered into the
LEGS page
• The VNAV mode of the FGS must be
selected (indicated by a “V” prior to the
active vertical mode)
• The Preselected Altitude must be set at,
or beyond, the VNAV altitude
Figure 16-86. Active Legs Page with
VNAV Altitudes
The default VNAV glidepath is a 3.0˚ descent
angle unless otherwise published in an instru-
ment procedure. The pilot has the ability to
modify this angle on every leg except for the
final approach segment between the Final Ap-
proach Fix (FAF) and the Missed Approach
Point (MAP). The FMS may create an angle
other than 3.0˚, if required. The glidepath is
based on aircraft position relative to the asso-
ciated waypoint, a commanded vertical direct-
to, or the associated waypoints position relative
to a prior waypoint with an altitude restriction.
When two or more waypoints in a flight plan
have altitude restrictions, and they are suffi-
ciently close in proximity to each other the
FMS will compute the best glidepath to meet
the requirements of all altitude restrictions. In-
stead of flying a 3.0˚ path to a waypoint, level-
ing off, and then flying another 3.0˚ path to the
next waypoint, the FMS will adjust the paths
to varying angles resulting in a continuous de-
scent. This is sometimes called “smoothing”
the descent.
A magenta Top Of Descent (TOD) circle will
appear on the display maps to indicate the
projected point where this descent will occur.
The TOD point will indicate when the vertical
deviation indicator nears the center position
on the vertical deviation scale (Figure 16-87).
This indicator is sometimes called the
“snowflake” or “star”. As with Glideslope op-
erations, these GPS Glidepath operations will
only capture VNAV when initially below the
projected angle. If the aircraft is already
passed the descent point, manual intervention
is required to place the aircraft in a position
where the FGS can capture the glidepath.
When the FGS captures a glidepath, the verti-
cal mode will be annunciated as VPATH when
NAV is selected or VGP when APPR is se-
lected (Figure 16-88).
VPATH will allow the FGS to level at either
the preselected altitude or VNAV altitude,
whichever it encounters first. It is necessary to
be aware of the armed altitude mode when ac-
complishing this maneuver. ALTS indicates
that VNAV will reach and level off at the pre-
selected altitude even though there may be
multiple step downs in between. This indicates
that smoothing the descent is possible and an
intermediate level off is not required. ALTV
indicates that VNAV will reach and level off
at the next VNAV altitude posted in magenta
above the VSI. This indicates that smoothing
the descent is not possible and the aircraft
must accomplish an intermediate level off. An-
other TOD will appear indicating where the
descent will begin if there is another altitude in
the FMS. The use of NAV and VNAV should
EXEC
NEXT PREV
MFD
DATA
MFD
ADV
CLR
DEL
BRT
DIM
DEP
ARR
PERF LEGS FPLN DIR
MSG
TUN
IDX
MFD
MENU
A B C D F G
H I J K L M
O P Q R T U
V X Y Z
SP
/
E
N
S
W
1 2 3
4 5 6
7 8 9
+ -
/
0
/
ACT LEGS
HUT
2/6
[
[
LEG WIND>
---/ 3100A
---/ 3600A
CEPGA
FEBIT
FAXIM
THEN
054
o
6.0NM
144
o
6.0NM /
/ /
- DISCONTINUITY -
---/ 3600A
3.0
o
0.0
o
3.0
o
//
//
//
/
/ /
/
307
o
9.5NM
/
---/-----
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FOR TRAINING PURPOSES ONLY
16-48
KING AIR C90GTi/C90GTx PILOT TRAINING MANUAL
16
A
VIONICS