ifr instrument navigation
TRANSCRIPT
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INSTRUMENT NAVIGATION
IFR Navigation Charts
[0Chart back page
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UNICATION FREQUENCIES
irHEER
PAC CABLE 26.7 SHOULD BE CONTINUOUSLY MO\ TOED
IN UNCONTRCLLEJ AIRSPACE AND WHE\ VF \ CON
— ROLLED ARSPACE
UNLESS ANOHER REQUENCY IS NICRE A
PRO
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AREA CONTROL C.E\TRES and TERMINAL C.O\R0 U\S
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There are three types ofTFR Charts:
1) Terminal
Charts,
wh ich provide radio navigation data for some of the
busier airports (quite similar
to
VTAs; 2) Ei2route Tow Altitude Charts, wh ich provide radio navigation data
for the en route portion of flights,
u p
to, but not including 18000' ASL, and.
3) .Enroute High Altitude
Chaf
ts.
wh ich provide similar data for the airspace at FL I 80 and above.
LE Charts are Lambert Conformal Conic Projection
charts,
and are similar to VN C Ch arts in that a straight
line on an L E represent a great circle route.
Communication
On backpage of the L E are two blocks ofiniormalion, the lirsi concerning the VHF Ircqacncics assigicd to
each oldie n'ijor airports on the chart with control towers (including .\TIS, T ower and Ground Frequencies),
and the second concerning the ,rca Control Centre and Terminal C ontrol VHF frcquencies including
peripheral station radio Jequencies
On the chart itsell the name oitbe applicable Area Control Centre
as well is the PAL ftequencs, are
I
entified using a boxed RrmaL Th e PAL box on the right shows
that
Vancouver Centre can be conlac L ed
On
1340MFE'., aswell38l.4MHz, (UHF).
PAL
VAN COUVFR
134.0
81..
Scale
The scale of
he
L B C harts vary—in the above example, tbr instance,
the
upper le±t and right corners of the
back page show that LO 2 provides a scale of 18 NM per U', while LO us scaled
at
20 NM
to 1 .
This
variation in scale, however, is of little consequence, since all distances along airways between navigation aids
and betweei intersections are published on the chart. In tho case that a n'asuremeiit is
r eqnir ed—for exaniple
between a n avigatioii aid aixi an airport—a scale b ar that appears at the top and bottom of the chart can be
used. Simply mark the distance on the edge of a scrap piece of paper and then position the paper next to the
scale to read the d istance.
Airspace
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N ote carelii]ly the L egend that appears or LE charts Or
the hottoiii tight-hand corner oFthe L egend—tinder
fVhsTcellaneous—we
are told that all
green-shaded dT&(1S
oI'the Ch art indic ncontrolled airspace below
18000' ASL, while the
white areas indicate coiitrolkd airspace
below
t f i L6
altitude, including L ow L evel
A irways. arid Transition Areas. Th e Ch art ftirL her deh neles areas wh ere coiiL rolled airspace exists
above
12500' AS T, (L ow L evel Airways and Control Area Rxinsions)—aU
green areas pattened with white
square (with green shade) /iatdng.
Finally, iiote under this section is the description of isogonic lines
(darker green and (lashed). Note also the
Area Minimum Altitudes (AMAs),
which provides 2000'
clearance over the obstacle within the quad rantat(establislied by degrees longitude and latitude).
MOCA and MEA
Perhaps the m ost important information on the bE for the 1 1 R pilot is the
MOCA (Minimum Obstruct ion
(1earance Al/it ude'i), wh ich is marked with an asterisk, and
MEA (Minimum E n Rou te Altitudes), which lack
an asterisk (sec depiction below).
M E A
0
0
MOCA
To-.al I4rV bet'ieen
Chart
radio
cI cIor
.r)rr1[)I I IiC
depictions for
airways B12
green shade)
and V334
The MOCA
provides on altitude above sea level in ejiecl between radio fixes on low level afrwavs or air
w
outes that meet the JFk obsruciion clearwe requirement /r the route segrneni.j Importantly,
tI
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11'R. obstruction clearance rcquircniit varies with whctlr or not an airway or air route is located inside or
outside a Designated Mountainous Area (DMA).
Outside the
DMAs, the MOCA provides 1000'
clearance over the h ighest obstacle within
5 N M of the aircraft; inside DM A s 2, 3, and 4, this clearance
increases to 1500', and in
DMAs 1 and
5
this clearance increases to 2000.
In contrast, the IvthA provides an altitude above sea level between specified fixes on aThvays or air
routes that assures acceptable navigational coverage, and which meets the liY? obstruction clearance
requirernents.
Accordingly. MI.A w ill always be higher than MO CA .
Also note that VHF /UHF airways are depicted in black ink, while L1/MI' airways are i n green. You will not
have d ifficulty determining the proper od d/even altitude to fly as the even altitude direction associated with
an
airway is indicated by the
pointed end
olihc airway identilicatioti box .
Th e Following show the relationship between M EA and M O CA as they are applied to airway segtmnts:
M E A
and MOCA based ort
liltrfl:
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EAndMOCA
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ssdcrinav1tron
facilities r>es
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••.•••.•••.••••••••I.•••.•••.•••••••••••••.•
........................
•••••••••••••••••.•••••••••••••••••••••
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N ote that each of the Fixes d epicted above w ill actually appear as an intersection on the L E chart, including the
means by w hich th e intersection is determined— i.e., DM E, a radial or hearing from a neigh bouring radio aid.
Minimum Reception Altitude
The TvThum urn Reception Alti tude
(MRA) should not get confiised with the
MOCA and the
MEA,
While the
latter provides obstruction clearance data, the MR A o nly provides reception altitude guidance for published
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intersections. Specifically, the MR A is provided for specific Vi 11'/L i
11'
intersections and specifics
the lowest
altitude above sea level at which acceptable navigational signal coverage is received to determine the
intersection.
Tw o intersections arc depicted Mow -1(onch and Kanoo Intersections. Ihey share the
saiir IVII(A (14000'
A SL ). N ote that th e co-ordinates for the intcrscctioiis are provided, as is the rad ial, idcnthicr, and frequency
for the VU R used to establish the positions.
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MPA
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Radio Aids, Distance and Course Data
All radio Aids—L e., ND B, VOR , VOR TA C— are orientated to magneticnorth
in
the
Southern Domestic
Airspace and
true north in
the
Northern Domestic Airspace.
While the azimuths are correctly positioned,
other navigation aid symbols may be po sitioned for sake of clarity.
lhc radio aid, distance and course data for the airway V i 12 between Calgary VO RI'AC and C ranbrook
VO R is examined in detail below. N ote that the actual distances between sinboL s arc only approxinttcd for
the sake of clarity.
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Navigation and Communication Data Boxes
The radio aid data boxes are virtually identical to the pattern wed on VFR charts. A
heavy line
around the
navigation aid dal.a box indicates the fciLl.y is co-located willi FSS. Tn the case
a thin-lined
box, FSS is not
co-located with the iàciliiy. Remote FSS communication equipment is established at rrrany radio aid sites, and
these are indicated by the appearance of a
sub-box
below the navigation aid data box.
Standard frequencies-126.7, 121.5, and 243 :tvHlz—are available for contacting FSS where FSS is cc-
located at the radio aid facility (heavy lird data boxes), unless otherwise noted. Additional frequencies used
by FSS will be published above the data box, but note that the standard frequencies will not appear here—
instead, it is implied that they are usable. If any of the standard frcqucncies are not available, they will be
shown with a line through them. N ote that the standard frequencies do not apply to thin-lined data boxes
showing reniote I'S S communication; in these cases, only the frequencies published above the data boxes can
be used,
Below appear three varieties.
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Airport Data
h e erodrome and erodromc Data depiction on L FR charts are conventional, arid d o not vary substantially
for VF Rcliart relèrences. Importantly, howev er, airports with
published Inst rurneiu approach
procedures
are displayed in
black ink.
Changeover Points
Nomially the radio aid uscd for tracking an airway is changed between the anch oring facilities at the half-way
,mrk. W here this changeover point is diffcrcnt, it is niarkcd as indicated bckw.. En route from VO R
A
to
VO R B, the VO R A is selected until the 102-N M m ark is reached, and then VU R B is selected,
ADF, VOR, and GPS Navigat ion Procedures
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el
The CPS Waypoint quacrants for the 010 Track, as
viewed frrm a properly orienLed aircraft
o n
Homing and Tracking
To home to a VOR station or GPS waypoini:
tune and identify the V O R station or (}PS wayp oint;
centre the CDT
with ()BS
that provide a "to" indication;
fly a h eading to rnahii.ain the track— if theCDI migrates icli, you are to th e right of track; if the C DI
migrates righ t, you are to th e ic ft o ['track.
To ilitercepi apre-determined track using VOR or GPS waypaint
•
tune and identify the VO R station or GPS vvaypoint;
• scicct the track desired using the O RS ;
•
orient the aircraft so iliat the desired track to or Iorn the VOR or G P S waypont is the same as the
airTa1ts bead ing (paralleling the track);
• note wheth er the VO R or G PS w aypoint is ahead oll- he lal.eral axis o['the aireralt (indicated by
a
"to"
indica(ion), or behind th e lateral axis (indiealed by a 'lrom" indica(ion);
•
ilibe CDI is on the right oientre, add the desired wilercepl angle to the current onentaicd heading and
fly the intercept; if the C DI is on left, subtract the d esired intercept ang1;
wh en the C DI centres during th e intercept, alter course to im, intainthe desired track.
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The NDB quadrants for the 030 Track, as
viewed from a properly orientated aircraft
03
0
To
home to a station using ADF:
• tune, idcnti1 and test the NDB;
•
note the relative bcaring
to
the
N
DB and turn the aircrdi so that the rclativc bcariig is 360' (ic., the
magnetic heading of the aircraft equaL s the magnetic bearing to the 1\t)B);
•
fly to maintain a relative bearing of 360'.
To intercept a pre-deterinined track using ADE:
•
tune, idcntify, and test the N L )B;
• orient the aircraft so that the d csircd track to or from the NDB iq the
same as the aircraft's heading
(paralleling the track);
•
note wlictlicr the bearing indicator (the needle) is indicating right or left of the 1ongtudinal axis of the
aircra Ii;
• if the bearing indicator points to the right oflongii.udinal axis, add the desired intercept angle to the
current orientated heading and fly the intercept; if the bearing indicator points to the right oflongitudinal
axis, subtract the desired iiiercepi. ange;.
• iFyou are intercepting a trackfrom the NDB, you slowly'pull the tail" o['the bearing indicator to nttc1i
the intercept angle—wh en the tail "opens" to match your intercept angle,
you
are "on track" and should
now L urn on course iF you are intercepting a L rack
to
the NUB, you slowly "push the head" o[the
bearing indic(or to match the intercept angle—w hen lie tail "opens" to rnaleh lie intercept angle, again
you are "on (Tack" trid should now turn on course.
Th e irfiereept angles used are the sanie (unless otherw ise prescribed): a 45' angle is used w hen intercepting
a
track ti
-
urn a sL a(ion (radio navigation aid), and a 900
angle is used w hen inlercepling a track to
a
slaLion.
Orientation—Paralleling the Track
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The key to intercepting a desired track is first paralleling the track. When you get comfortable with
interceptions, you will start skipping this phase, but u ntil you get proficient at it, always parallel the track before
you intercept it. By paralleling the track, you are ectivcFj orienting yourself and the aircraft to the ground
transmitter or waypoint.
Is it located in front of o r beh ind the airerafi2 is it located to the left or to the rir?
W ith a VO R or (IPS waypoint, once the track is paralleled, the hifomtioii derived from the instrument
display can be directly applied to your mental picture of your location—you are looking for the "F o" or
1rom" indication to determine if it is ahead or behind, and you look for the needle deflection to determine W it
is right or left. Consider the depiction below:
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Intercepts and Tracking
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NavigationFormula
Relative Bearing
Magnetic bearing,
sontirncs shnply referred to as
bearing, denotes the horizontal irngtictic direction to or
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from any p oint. If the mag netic bearing (or hearing) to a station is 27 0°, for example, this m eans that we are
directly
east of
the station similarly, if our bearing to a station is 1 80c
,
we are directlynorth.
Relative bearing is the
position of an object relative to the longitudinal axis of the aircrafl. If
an object
lies directly oft'the
right wing of
an aircraft, it would be considered to be at a relative bearing of 090'. If the
aircraft is eastbound and an object is directly to the north of the aircraft, the o bject still remains at a relative
bearing of 27 0°, even though the inagnel
t: bearing
is 360°.
An aircraft is flying on a tmgnctie heading of 27 0', An A DF indicator shows a relative hearing to a local N DB
as 010°. To proceed directly to the NDB, what magnetic heading would he flown?
Here iF, the krnuh to he used:
Magnetic Bearing = Magnetic Heading
+
Relative Bearing
or,
MB=MH RB
MB =270
I 010
MB = 280
10 fly to the N DB (or beaco n), the pilot would fly 280
N ow, what would happen if the
niagn elk heading and
relative hearing,
added togethcr.
equalled a value
greater than 360.
The solution is straightlbnvard—s'imply take the sum and subtract 360. For example,
an aircraft is flying a heading of 2 70
0
and the relative hearing to the station is 190'. What magnetic hearing
should the pilot fly to proceed d irectly to the station?
MB – MH+RB
MB-
70 + ISO
MB –
451)
MB
– (450 –360)
MR
= 090
10 fly to the 1 . JiB (or beacon), the pilot wou ld
fly
090O .
A similar variation on the formula can be encountered w hen d etermining the relative bearing. To establish
relative bearing by itself on one side of the eq uation, simply sub tract Ml I from b oth sides:
MB–MH+ RI)
MB-MH–(MH+RB)-MH
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1v1J3-M1I=RB or,
I II II II
O n occasion you will find that the
magnetic hearing Ls greater than the aircrafi .c magnetic heading. A
negative answer will not do, of course, but the solution is quite straight forward —cfinp1v add 36O' to the
magnetic hearing.
Here is an example: Th e aircraft's magnetic heading is 27 W
,
and the m agnetic bearing to
an N DE3 is 1
hat is the relative bearing to the N
Dif?
RB - MB - MH
RP - 10-27()
RB - (180-360)-270
RB = 540-270
1113 = 270
So, let's see if this uxikcs sense. T hc aircraft is flying
westbound (i.c., from right to bft across your piece of
paper). '1he magnetic bearing to the station is 180', so that would p u t
the station below th e aircraft
at
the
bottom ofth c page (i.e., the south). W hat wo uld be thc relative bearing of this station with respect to the nose
of the aircrafl—ycs it would be directly off the left wing, or
2700
measured clockwise from the aircraft's
longitudinal axis
Time and Distance to Station
Th ere are two lörmu las to lie aware o[w liicli allow a pilot to determine the
time or distance
to an NDB or
YO R station. To use the lbrrnu la, the pilot must first he tracking directly
to the
station in question; then the
aircraft is turned 90° frorri that heading to a perpendicular track. The pilot L hen notes the ch anges in L he
bearing to the station and the am ount of urne required prod uce the bearing chan ge.
Th e two equations are as Ibilows:
Time (seconds) required for degrees or radials change
Time to Station (minutes) =
Number of degrees/radials changed
I'AS x Time to station in (minutes)
Distance to Station ([NM) =
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60
A pplying these formulas to VO R s, for example, let us assume that an aircraft is tracking inbound o n the 27 00
Radial of a VOR. Fhc pilot wishes to know the aircraft's distance from the
VOl? slatiün. To do this, the
pilot then turns the aircraft to a head ing of 360"', and starts tinning After two minutes the pilot notes that the
CDI has deflected I '/ dots—or what is three degrees. Here comes the math:
129
Time to Station (minutes) =
Time to Station (minutes) = 40
The arrali is 40 minutes from the VOR.
Assuming that the airerafi travels at 120 KTS lAS, the pilot then wishes to estimte the distance of the aircraft
fi-om the VOR. here we go:
120x 40
Distance to Station (NM)
60
Distance to Station (NM) =
U
Th c aircraft is 9 () N M from the VO R.
N ow let ui apply tFese lhrwitilas to u.SC o['NDR s. Again the aircraft iF. tracking directly to an ND B and the
pilot wishes to determine the exact time and distance required Iör station passage Using a fixed card ADF the
pilot tL uns
900
W orn the course and notes that it takes 2 minutes lbr the relative hearing to the N DB to change
from
2700
to 262'. Again, here comes the nttb: 120 seconds divided by 8 eqwils 1 5— the airerdit is
IhereJjre 15 minutes Worn the NDB. Tithe TA o[the aircraf is 150 KTS,
150
is multiplied by 1
5
L o equal
2250, arKi 2250 is divded by 60 L o equal 37 .5--the aircraft is ihereR,re
37.5
NM from the
NDB.
Track Measurement
W hericvcr it is required to produce a qu ick measurement of csdniatcd cii route along an airway with a dogleg,
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8/17/2019 IFR Instrument Navigation
15/15
or a series o ['airways with dilrcrcnt tracks, an effective way
to do th is is to "eyeball-estimate"
an
average
track. When the average track is dctcrinincd, the forecast winds can be applied to dctcrrninc the average
groundspccd and the total distance
of the actual routing can be applied to the avcragc ground spced to
determine th e total tinic on route.
Here are sonic examples of average tracks
References:
AIM
G L L N
5.1 (Glossary of Aeronautical Terms)
2 ibid.
3 Unlike a VOR, the NDB signal is tested every tint a new NDB is selected. If the APP is equipped with a
"test' hiaion, this is pressed and the bearing indicator will nioc to the 090'relative hearing position; ifthe
A DF d oes not have a lest lcatL irc, move the liinclion scicetor switch W orn the AD F position to the AN T
position (the ANT position removes the directional loop antenna" from the systern allowing only the non-
directional "sense antenna" to receive the
signal), and
again the 090° relative bearing w ill be received.
In lad, you do not add or subtract, but instead simply glance at
t h e A D F rotating card and read the intercept
beading—presui -
ning, oftourse that you have "bugged" the orientttion heading.
In
the event ola Fixed card
A DF , simply transpose the bearing indication onto the h eading indicator; as you turn to the intercept heading
you should see the desired track under either the 45'or
900
marker on the h eading indicator.
.This
is quite tricky business and you should spend titne on the ground re-viewing this tail pulling" and "h ead
push ing; on a scrap of paper—b ut of course it is best seen in the air.
Mary Bar/ed a/er llarv Dad Roast IJeef or Mary 1/ad Roast Bee/—i4arv Bar/ed.