Radio-NAV = Radio Navigation
Navigation-Systems are very different in type, construction, and
integration - but they are all the same in function! Here in the Cessna
you see the "basic style" in which each function had it's own unique
unit, which is integrated into the instrument-panel and operated from
the unit itself. In modern aircrafts those "functional units" are more
and more "black boxes" which are installed somewhere out of sight, and
their displays and operating components are often integrated into other
units. Let us learn about the functions based on the neatly arranged
unites of our well equipped Cessna.
We will describe the Units in the order they are physically installed,
from top to bottom (see the picture
Audio Control UnitAll the Radio Units do produce some audible signals, may it be words,
Morse-codes, or any other kind of signal. All these sounds on one
loudspeaker at the same time may not really be understandable by the
human ear. The "Audio Control Unit" enables the Pilot to switch on/off
audio-output of each device to unique loudspeakers or keep them quiet.
In our Cessna this unit is non functional (yet) - it can be switched
etc. - but the sound is not differentiated! But because each unit has
its own individual Audio-Control button, that is no major problem for
||The rotary-switch at the left side connects the microphone with the transmitter wanted.
Below that there are the 3 lights with special meanings during the final approach:
light and a sound of 400 Hz,
positioned between 4-7 mi out
light and a sound of 1300 Hz,
positioned between 0.5 to 0.8 mi out
Marker: The white
light and a sound of 3000 Hz -
signaling you are over the Touch-Down-Area of the runway!
A "Non Directional Beacon" (the picture on the right)
basically broadcasts a signal that says “I’m over here”, which the "Automatic Direction Finder" (the picture on the left) inside the plane receives and thus tells you, the pilot, “the station is
over there” (i.e. it points into that direction with the needle (picture in the center)). For that
to happen you just tune the ADF to the
NDB-frequency and watch the ADF-Display (needle). (the picture in the center).
In the above case the NDB would be 20° to the right -- independent of
the actual course! To get to the NDB we just follow the yellow pointer!
In this case we would turn right until the pointer is in line with the
ocher triangle at the top of the instrument - for that procedure the
compass rose is of no
importance at all -- you may set it as you like!
You find the location of the NDBs on charts marked with a red circle
surrounded by a red cloud (see the
right picture above, that one is from the MPmap). Like VOR's, NDB's
a full name (e.g. "REIGA"), and an ID (e.g. "LV"), and of course a
frequency (e.g. 374).
Like with VOR's we need to hear the indent to be
sure we’re really tuned into
the right station! Like all radios,
the ADF receiver has a dedicated volume control, labeled “VOL”.
The volume control also functions as an on/off switch, so if you turn
the way counter-clockwise, it will shut the receiver off.
Unfortunately, at the time of writing, the indent function does not
so for now you cannot verify the NDB-Station by listening to the
transmitted Morse-Cod. So double-check that you are on course by other
means, e.g. MPmap or Map
Notice there’s no OBS to set for an ADF — the
needle just points to the station.
Operating: (Compare the pictures in the heading)
that smaller rotary-button labeled Off/VOL. You can operate it as usual
by mouse-clicks into the hotspots or by the mouse-wheel.
- When turned all the way left it will switch off (and the
gets dark) - in all other positions it will vary the volume of the
Morsecode transmitted from the NDB.
- Unfortunately, at the time of writing, the indent function
does not work yet, so for now you can only use the "on/off" function.
- ADF/ANT: In
the most left side of the display there may be written"ADF" or "ANT",
you switch between those two modes by pushing the ADF-button:
- You need the "ADF" mode to
navigate - so watch that this one is active when flying
- The "ANT"
mode is used in reality to indent a NDB, because it gives better audio
reception. While in this antenna mode, however, the ADF will not point
the station - the needle will then be parked pointing directly to the
- So make
sure you always have the "ADF" sign in the display!
- BFO: The
additional BFO-mode enables the device to receive the Morse-code also
from "non modulated transmitters" -- we do not use this!
- FRQ: Switches
between the 2 preselected frequencies:
- The "selected"
(active) frequency, displays on the left
- that is the the NDB-frequency where our ADF-needle points to. Watch
it: If the needle just points straight to the right and does not
when changing the heading - then you are not receiving any signal! (Check that you are in "ADF"-mode and that
the "selected" frequency is in range!)
- The "standby"
frequency is the one you will use when pushing "FRQ". Only this
frequency you can change by the big dial on the right! Use that as
- by moving the mouse-pointer over the dial and rotate the
- or click with the mouse into the hotspots left or right, left
button for small steps, center button for big steps
- or use the "Easy-Setup"
- FLT/ET: pushing
this button will replace the displayed "standby-frequency" with a
and and when pushed multiple times it changes between the modes FLT and
- FLT = Flight Time: Displays the passed time since you started
- ET = Elapsed Time: Is a Stopwatch, which is then controlled
with the button SET/RST
- To display the standby-frequency again: Push FRQ
- SET/RST: Sets
the Stopwatch to "0" and starts it at the same token. So you cannot
do a stop/continue!
- Watch it: Hitting
this button will always reset the Stopwatch, independent of if you see
it or not! e.g. even when you are in the "Flight Time" mode! That is
a little confusing (for people like me)! So watch it.
(left lower corner of the "ADF display" (see above picture in the center):
- Turning that knob will rotate the internal wind-rose in the
instrument. That does not influence our course etc. - but if you
(manually) set that to the same heading as the "Heading Indicator",
then the ADF-needle does not just point to the NDB-location, but also
gives you the real heading to it.
- May be you want to change your course at a certain point of your course (e.g. 46° to a certain NDB), then you
- adjust the NDB-scale to indicate the same as the "Heading Indicator"
- then you turn when the ADF points to 45°
- (That is laborious? Yes, it is. And Yes:
There are instruments that link the scale automatically with the
"Heading Indicator", but those cost extra money - what we poor Private-Pilots do not have!)
When using the ADF/NDB for navigation, be aware that you always just
follow the pointer directing you to the transmitter - you are not following
a unique course or radial (like e.g. when using a VOR)! See what
happens if e.g. there are considerable crosswinds:
We will fly to that "green NDB" directly north of us
(a) shows us the "perfect" setup: It is a wonderful day with no wind:
So we just turn till the needle points straight up, and take some rest
we are at the NDB. This, by the way, is the only situation in which
heading and course are the same!
(b) shows us the more realistic situation: Usually there will be some
wind, in our case coming from the West (left). So if we just set the
heading (e.g. let George hold it) and take a rest -- ... --- until we are out of fuel! We very definitely will never arrive at
(c) this time we do not just set the heading - but we continue to
ADF-needle. And doing that we will notice that over
time we do change
our heading - actually we are not flying a "straight course" but a
somewhat funny curve! But at least we will arrive at the NDB - somehow!
(d) so we should find a compromise between heading and course! If you
were good in mathematics you could calculate which heading you have to
hold to fly the wanted (360°) course. Real Student-Pilots have to
do/learn that - but for our fun-flying that might not be necessary.
Just watch the heading and the ADF-pointer: Try to find a heading at
which the ADF-pointer remains stable! i.e. when the ADF-pointer
deviates to the left try a heading that will not just bring the needle
to the top again - but a little further, e.g. 340° instead of the
course 360°. With some training you might get better that way then
when calculating - because my experiences were: Whenever I had
calculated the right heading for the reported wind - the wind
for an application of this see the
"IFR X-Country", chapter "1) From KRHV to
You may find further detailed
informations on http://monterey.militaryflyingclubs.com/Other%20Docs/KR87.ADF.pdf
The C172p is equipped very generously with 2 identical
Communication/Navigation radios! Each of those 2 consists of 3 units:
- The "COM"-radio (the
left half of the above unit): That is the radio for
communicating with the outside via MPchat
or FGCOM, etc., may it be
with other "Multiplayers" or with "Artificial-Intelligence Functions"
- The "NAV"-radio (the
right half of above unit): That is the radio for
Navigation to tune in to VOR and/or ILS
- The "NAV"-display" (the right
- displays the instructions from VOR or ILS
transmitters, as well for the horizontal directions (radial or
localizer) as for the vertical direction (GS = GlideSlope)
- has a knob (down left)
for setting the wanted "radial" to be tracked
The Controls of the
- Volume: Beneath each Radio there is a small
rotary knob to adjust the volume. If you turn the left one all the way
to the left, it will switch off the complete unit.
- Display: There are always 2 frequencies
shown: On the left the "selected"
and on the right the "standby".
That way you are able to preselect a frequency to be used later while
you continue to work with the "selected" one. You can only adjust the
"standby" one - and then exchange the both by clicking onto the white
button underneath the display.
- Frequency: You
set the frequency using the bigger knobs at the right, by
- clicks with the left mouse-button into the hotspots at the knob
- that adjusts the frequency in small steps
- clicks withe the central mouse-button/wheel into the hotspots
- that adjusts the frequency in bigger steps
- rotating the mouse-wheel inside those hotspots
- type the frequency into a GUI - see the following chapter about
→ Equipment → Radio Settings“
- that one has the advantage that you can set ALL frequencies for both
(standby and selected!) and at the same time also ADF, DME, TACAN,
Radials etc. - see the following chapter "Easy-Setup".
the VOR-frequencies: After you have set a VOR-frequency, first
turn up the radio-volume and
listen and check it's Morse-coded identification! Because especially in
high altitudes you will find many, many VORs and even some with the
same frequency! You only can be sure to have the right VOR when you
hear its Identification! In the simulator that may be worth a laugh -
in real life that could become very, very critical!
With the GUI "Menu
→ Equipment → Radio Settings“ you can set all
Radio-units by typing in the wanted numbers:
In the example above there are set all values as used in the two
"Cross-Country" flights, as well during the VFR
Cross Country as also for the IFR Cross
Country. In detail that are:
|KLVK ILS 25R
|only NAV1 can be used for VOR- and ILS-approaches when using
|the radial "229" for the VOR-ECA must be set later, when that
VOR gets switched to "selected"!
|KLVK – acronym title="Initial Approach Fix">IAF
|See the chapter "IFR approach"
|In the very
rare case of a DME,
that is not integrated into a VOR
|In the newest FlightGear Releases there may also be a
Transponder-field to be used with VATSIM. That one then should be set
to 7000 for VFR - otherwise as advised by
|here set for
the Carrier "Eisenhauer",
at Marseille (France)
With the button "ATC
Services in range" you open another GUI (formerly located under "Menu
→ ATC/AI → Frequencies“):
When that GUI opens it will directly present you the "nearby" airports
in the upper line. Those you can select by mouse-click.
But you also can input any airport (ICAO) and check its frequencies.
After a few seconds (voice-stream loading-time) you then should hear
the ATIS informations - if not check your COM settings and/or general
Audio-settings, see e.g. "Menu
→ File → Sound Configuration“
- e.g.: Click onto "KRHV", that will present a sub-GUI with the
available frequencies. Set the ones wanted into the COM's in above
"Easy Setup". e.g.:
- 125.20 → into COM1 Selected, to first listen to the ATIS at KRHV
- 119.80 → into COM1 Standby, which you will use after that (notice: There is no "GROUND" at KRHV!)
For FGCOM-User: The frequencies
shown here are the generally available
frequencies in FlightGear, not all of them are also available in FGCOM.
For the available FGCOM frequencies see the data-file "phonebook.txt“
in your FGCOM-directory!
In windows that is commonly inside the $FG_ROOT, in Linux it is mostly
inside your $FG_HOME.
NAV-Radio = VOR
NAV-Radios are used for wide range radio-navigation (VOR) as well as
for unique approaches (ILS). So you see that VOR and ILS are
technically very much the same - let us see what the differences are:
Please find in the following first some general explanations and
then several descriptions of how to use them (see Standard_procedures). For this we
again the area around the San-Francisco Bay, that we also use in our
flight trainings (e.g. http://runwayfinder.com/ --> KSJC):
may be located anywhere. They send out long-ranging radials, covering
all directions of the wind-rose.
Depending on the surrounding area you may be able to tune to it already
100 mi out (but e.g. not in a 20 mi distance, if there is a mountain
between you and the VOR!). On maps you notice VOR's by the Windrose-Scale around them (see below).
are always located directly at a unique runway and do send out only one
single "radial" - that is the heading of the runway, called the "localizer"! You
may be able to receive a localizer up to 50 mi. out
- In addition the ILS may send a Glide-slope Signal (GS) - which
functions exactly the same as the localizer - but guides you vertically
to the "Touch Down Area" of a unique runway. The GS-signal usually only reaches 10 mi out from the threshold!
|In the graphic on the left
see 2 VORs, named "OAK"
Let us analyze line by line what a typical aeronautical chart tells us
about e.g. the "VOR
SJC" (see it outlined
in the right lower corner):
tells us, that this is a civil VOR with an integrated DME. (In the
left upper corner you see the example of a military VOR == the
JOSE: is the full name name of that VOR (which you cannot use e.g. in a
During the flight the OBS of the VOR tells the Pilot on
which magnetic bearing to or from a VOR he is flying. Most VOR's will
indicate also the distance (see DME) to it. The
bearings are in magnetic degrees and are called "radials". In the
graphic on the left you see 2 bearings:
- 114.1 Ch 88 SJC ...
: is the frequency you would have to set into your NAV-radio
- Ch 88 : is a frequency for another
type of NAV-radio (which we will not use)
- SJC : is the UID for that VOR (which you would
set into a route-planer)
- "... .---
the Morse-code for "SJC", which is transmitted and should be used by
you to identify the station! You hear those dashes and dots as longer
and shorter sounds on your radio - between each letter there is little
1. "114° FROM" coming from the
2. "002° FROM" coming from VOR SJC
Those two radials happen to meet somewhere, and this unique meeting
point is given a special name: "MISON". Thus it
is a very important "FIX"-point in
the Bay-Area! Such a FIX
is not seen during strict VFR-navigation, because it is just a crossing
of two radio-signals - so do not try any sightseeing for it! By
defining such FIXes
traffic can be routed not just by defining VORs as way-points, but also
by the crossing of two radials. Those FIXes are very
often used as "waypoints"
as Reporting-Points for ATC, etc.
OBI: The VOR/ILS-Indicator:
As already mentioned before, there is an additional instrument for the
VOR, that we will explain now:
"Omni Bearing Selector": When you rotate the knob at the lower left
corner, the wind-rose-scale inside
instrument will rotate too - placing the currently selected radial at the very top
the scale: See e.g. the value "N" (= 000° or 360°) in the picture. With
this setting you fly with a heading of 360° "TO" (=North) or "FROM" (=South) the
"Course Deviation Indicator": This is the vertical needle inside the
VOR-display. If that needle is vertically centered, it tells you that
you are on the selected radial - if not, it indicates into which
direction you have to correct your heading in order to return to the
= "Glide Slope": The horizontal needle in the instrument functions like
the CDI, but in the vertical direction! Watch it:
is only available from some ILS
transmitters, and its signal usually
reaches only 10 nm out from the "Touch down Area" of the runway.
The GS becomes active a long time later then the CDI - which is active
already 50 mi out and more!
Do you see
that little cutout at the right side of the center, now indicating
"TO"? In that window
will appear a "TO" when the radial brings you towards
the VOR -
otherwise it will show a FROM (or short "FR"). If
neither "TO" nor "FR" is indicated you are not inside a valid
range to a VOR with that frequency!
To make it
very clear: The "TO/FROM" indication does NOT
indicate in what direction you actually fly - it just tells you in what
direction the radial points - so yes: Although when flying on a radial
"FR 270" and a centered CDI you may very well be flying towards the
But in case you deviate from the radial, the CDI will indicate the
correction reverse! Have a look at all 4 possibilities and there
function when flying eastbound:
of the VOR
Showing left when you should correct to the left
of the VOR
Showing left when you should correct to the right
of the VOR
Showing left when you should correct to the left
of the VOR
Showing left when you should correct to the right
us try to analyze the above picture of the OBS: In that example we
follow the radial "TO 002°" towards the VOR - i.e. pretty much to the
- So we have used the OBS to set the compass-rose to 002°
(actually you hardly can do that very precisely with that instrument -
so I suggest to use the Easy-Setup to
input that value.)
- In the example the CDI points slightly to the left - telling us
we should correct our heading in order to get (back) onto the radial
- we obey that by turning about 10° to the left - i.e. to a
heading (on the Gyro-Compass) of about 350°
- if the needle remains as is or even moves more to the
outside, then we increase another 10° to the left (on the Gyro-Compass
now about 340°)
- if that still does not help add another 10° - but you
should not need more then 30° for correcting. Be patient: Depending on
how far you are away from the VOR it may take quite some time to see a
noticeable change! Do not overreact!
- when the needle starts to move back to the center, wait
until it is shortly before the centerline - and then turn back to your
case you have to repeat these corrections again and again
(i.e. because of heavy crosswinds), then correct your heading
(according to the Gyro) in that a way, that the CDI remains centered.
e.g. keep a heading of 355° (7° against the wind) in order to stay on
the radial/course of 002°!
HSI: Horizontal Situation Indicator
To the end a short summary:
| The Compass and/or
ADF show where your nose points to
the VOR/ILS shows the course!!
and helps you to stay on course, even when not using
an autopilot !!!!!
for an application of this see
the "IFR X-Country" chapter "Following the V334 to SUNO.."
for more technical details see e.g.: http://en.wikipedia.org/wiki/VHF_omnidirectional_range
Standard VOR ProceduresWhenever
looking for VOR's on navigational maps or MPmap etc. you should know
the different types available, together with their symbols on aeronautical
||Specifies a VOR without DME
||Specifies a DME without VOR
||Specifies a combined VOR-DME,
for both functions you need to set only the VOR frequency (the unique DME -frequency will be set automatically!)
|Specifies a TACAN (= a military VOR), those always include a DME, but no VOR for civil usage!
||Specifies a VORTAC, the all-in-one solution: It combines the civil VOR-DME + the military TACAN!
It does have different frequencies for military and civil usage, and both set the unique DME-frequency automatically
towards a VOR:
That means we are somewhere up in the air and want to fly to a VOR
(found in MPmap, Map, Atlas,
Aeronautical Charts, etc. -- or as advised by ATC):
- Set the VOR-frequency into the NAV-radio and move it into the
left display ("selected")
- increase the volume to listen to the Morse-code - make sure it
is correct, because there may be several VORs with the same frequency!
- Rotate the OBS until the CDI centers AND the
"TO/FROM" indicates "TO"
- when you rotate the OBS "wind-rose dial" a full circle (360°)
will center 2 times: Once on the radial "TO" and once on the
"FROM". Check your little "TO/FROM" flag and continue rotating it until
the CDI is centered while "TO" is indicated.
- if you do not get any indication check for
- is the set frequency correct -- and is it in the LEFT display
of that NAV that you are tuning (remember: you have 2!) ?
- is the VOR in range (max about 100 mi) or may there be
mountains between you and the VOR ?
- is the NAV switched on? (Well: Probably it is when you can
see the frequency in the display!) ?
- Follow the CDI-indication as described before
- When the CDI suddenly deviates very fast AND the
"TO/FROM" changes to "FROM" --> then you arrived over the VOR. You
now should either:
- just continue on the same course
- report to ATC that you arrived over the VOR, if ATC advised you
to go to that VOR (and maybe go into a "Procedure Turn")
- or change the course as you planned
Turning to a new direction over VOR
This time we do not just fly towards a VOR on a "TO-radial" as
above, but we want to change our course when at that VOR. Of course you
could wait till you arrive at that VOR and then rotate your OBS to a
new "FROM-radial" or start other actions there. But usually you are
busy with other things at that point (reporting, getting new charts,
etc.). Whatever time you need to do all that: It will look bad -- you
always will fly a loop. Better, based on cost, time and looks, would be
- While letting George (autopilot, i.e.: You must use NAV-1!)
keeping the CDI centered as
described above, we already set the "red bug" within
our "Heading Indicator" to the new heading (but do not yet activate
- Wait till you notice that the TO/FROM starts
moving - then push "HDG" (button on the autopilot) and
George will directly turn, even though he might not be over the VOR
- While George is still turning set your OBS (that is not in use
now) to the new radial
- and check that the "TO/FROM" now indicates "FROM"
- or even change to the next VOR and tune it in - in that case "TO/FROM"
would have to indicate "TO"
- And then order George to follow again the CDI (e.g. push the "NAV" button on the
Intercepting a radial to follow:
most big airports you will find a VOR. By using a radial of
that VOR you can directly intercept a radial and follow your most
course to a given point - just find out which magnetic heading you need
from the airport to the destination! That way you really get there,
independent of cross-winds, Compass deviations, errors (e.g. parallax
when reading the scales), etc. etc..
See the following example for such a procedure at the EDDF
(Frankfurt, Germany) airport, when after TakeOff you want to follow the
radial "FROM 270°":
- Before TakeOff set the VOR-FFM frequency 114.20 and the
course=radial 270° into your OBS. (Just
for learning: Notice that Frankfurt also had a big Military mission -
so that VOR is mixed: See the function VORTAX and the frequency
"114.20" for the civil operations and the TACAN "089X" for military
The interception-angel of 30° is pretty ideal to intercept without
overshooting - if the angle becomes bigger than 60° you definitely will
overshoot and will need several retries prior to be centered on the
- After TakeOff (and clearance by ATC) go onto a heading
that should intercept the wanted course in an angle between 30-60°,
i.e. if the departure was
- to the north: turn left to a heading of about
- to the south: turn right to a heading of about (270+30=)
- Make sure that the OBS shows "FROM 270"! (Otherwise you may end up in Moskau
instead of in Paris!).
your instrument closely when approaching the interception point: As
soon as the CDI-needle starts to move towards the center start turning
to the heading set in the OBS (in this case 270°) and then follow the
radial by keeping the CDI centered. e.g. if the CDI-needle moves left -
turn left a little more. Start with about 10° (in this case hold a hdg
of 260°) - if that does not cause the needle to start moving back into
the center, increase the turn to the left, may be another 10°, and so
on. But be patient: As you get further and further away from the VOR
the time to see a change in the OBS will increase, because the
difference (see the red circled "1") becomes larger and larger and thus
the time for a noticeable change in numbers (i.e. instruments!) will
with 1 VOR + DME
You should verify what you did by watching the DME: Are you really
getting closer or further away? What should it be?
- Tune one of your NAV-radios to the frequency of the wanted VOR in
your area (depending of your altitude inside an area of 100 to 200 mi)
and switch the DME-Selector to that NAV.
- You should now directly see the distance to that VOR (if not:
That VOR may have no DME, or you mis-adjusted the frequency, or..)
- Now turn the little knob at the left lower side of the OBS until
the CDI is vertically aligned. It does not matter if that is a "TO" or
a "FROM" radial, but note what it is --> You will need it later to
the direction on the map!
- If you need a very exact positioning take an aeronautical map for
- if it is not that important you may also take a street-map (and
maybe convert the VOR magnetic heading to a cartographic heading!
(Compare "The Route")
a straight line crossing through the VOR location under the angel of
the radial, it does not really matter if it is TO or FROM - the line
is good for both!
- Now see the scale of the map and mark that on the straight line!
And now it is important what "TO/FROM" radial you use! (See above!)
Define your position with 2 VOR
When we do not have a nice VOR with DME
near by, then we can use two VORs (if
they both are in range)
We then set their frequencies into our 2 NAVS and turn both OBS
s are centered. On an aeronautical chart you will already find
the VORs with the compass-rose around it - so you just have to draw a
straight line from the VOR-center through the wind-rose to the outside.
The crossing point of the 2 lines is our current position. (I
admit: Sitting in a jet cruising at Mach 2 will make that a little
tricky - but right now we are in a C172p, where it might be a pleasure
to learn that --> you will need it for your Pilot-License!)
seldom use this method directly when flying - but rather the reverse
when preparing a flight. e.g. if I plan to fly low in valleys between high
mountains I define navigational points that way - and just verify my
position during the flight. Then this procedure comes very handy to
make sure you are in exactly that valley you wanted to be! (Yes: GPS (maybe even supported by the
easier - but is it as much fun??)
position will be the better the more the 2 VOR radials are close to a
right angle - and the closer the VORs are to our route! Best it is when flying on
radial of one VOR and find another at about 90° to either side! For
that we find an example in the next chapter.
Of course you can do the same with 1
VOR and 1 NDB
or even 2 NDB
s, if you make sure the NDB
scales are set
exactly to the actual Gyro-Compass-Heading (and stay in sync with it, in case you make a turn or similar!)! Then you can set the
readings of the NDB
into the chart - but that will become significantly less precise! Also
s do not extend to far distances like VORs (although they may be very helpful in
marking airports and special points in valleys!).
Finding a "FIX"-point
- First we need to intercept the Radial "NAV-1 FROM 002" (See above
how to do that). And we make sure we are and remain centered on that
radial (may be the Autopilot could
help during our first tries!)
- Then we wait until the NAV-2 CDI starts moving
- then it may be a good idea to check if it is moving into the
direction - i.e. are we still before or already after the crossing?
- I admit: I always had problems with that - nowadays I just
move my "mind" into the VOR2 and look from there onto the NAV-2 CDI:
- If that points to the right it tells me: Correct the
heading to the right to
get back onto the radial -- i.e I am left of it --> that means I
- If that points to the left it tells me:
Correct the heading to the left to get back onto the radial -- i.e. I
am right of it --> that means I did not yet cross
- Compare: The_NAV-Display
- When both CDI's are centered you are exactly over that
FIX. But do not look out of the window trying to find anything: It is
just the crossing of two radio-signals -- there is nothing to be
are always located directly at runways in order to guide incoming
traffic to the "Touch Down Area" of a unique runway. They do function
exactly like VOR's, but:
- they do send only one very unique radial with the exact runway
heading, which is called the "localizer" -
i.e. you cannot change it! "Wonderful
- I do not have to care about the radial!!" you might say - and you are
right: You do not have to set it - in the "modern" Cessna -
- but there are
other models, where the CDI is not automatically tuned. In those models
you will not see how far you are off the "localizer" if you did not set
- and if some day you have enough money to effort a modern, expensive HSI, then you do have to set the runway direction for it's operation (have a look above at the HSI!)
- ==> So it is a good practice to set it always - to make sure you do not forget it when needed!
- most of them do send an extra signal, called the "glide-slope"
(GS). That works like a CDI - but in the vertical direction. The
function is the same: The horizontal needle tells you in what direction
- if the needle points upward: Do add power to
the speed of your descent
- if the needle points downward: Do reduce
power to increase
the speed of descent
- watch it:
The GS usually gets active only in a range of
about 10 mi - thus you might be following the CDI since a long time (up
50 mi out) prior that the GS gets active - most students get nervous
and believe the GS does not work, but I hope you know now - and just be
Did you notice: We did not mention a DME
within the ILS - because technically there is none! For a DME you might
use a VOR (in NAV2!) that is located on the airport - or look if there
is a standalone DME near the ILS! See e.g.:
localizer is 4 times as sensitive as a VOR-CDI
|In KSFO you see the example of an "ideal " setup: There is a VOR-DME
in the center of the Airport. So here you can use the VOR as support
to get you onto the ILS-localizer, and have a pretty exact distance
measurement as well for the VOR as the for the ILS and or Glideslope! So you can use the your
- NAV1 for the ILS
- NAV2 for the VOR (inclusive DME)
|In EDDf it is just a little more
challenging. There also is a VOR - but a little outside, which is still
good enough for aerial-navigation. But see the symbol - it does not have
a DME! But there is a standalone DME in the center of the airport. (For
that one is shown in FGFS only the military frequency. If you look into
other (newer) navigational maps you see it has a distinct civil frequency of
115.9 MHz (see e.g. http://www.ourairports.com/navaids/FRD/Frankfurt_DME_DE/).
That means you need to set 3 frequencies:
1) Set the VOR 114.2 into NAV2
2) Set the DME 115.9 into NAV1
3) Set the DME-Selector
4) Set the ILS-frequency into NAV1
first to "1" to get the DME
119.5 indicated in the DME
then switch to "HOLD" --> that holds the DME
, even when changing the NAV-frequency
The procedure for an ILS-landing:
- Set the ILS frequency into the NAV - if you want to use the
autopilot it must be the NAV-1!
explained above it is suggested also to set the localizer/radial to the
- Between 30 to 50 mi out, the ILS should become active, .i.e. the
CDI starts to point into some direction AND the "TO" flag should get
visible. Be aware of:
- When you come from a direction opposite to the runway-heading,
that indication is most probably reversed! (e.g. during Downwind)
- The same happens when executing a GoAround and thus flying in
the reverse direction of the localizer!
In a range of 5 to 20 mi out you should intercept the ILS
localizer. If your airport informations do not say otherwise do that a
little higher then the pattern altitude, which usually is about 800 to 1000 ft
above airport altitude.
- If the NAV + CDI + TO/FROM do not start to indicate about 30 mi
out, it is time to recheck the set frequency, look for mountains in your
Follow the CDI on that altitude, till:
- Starting about 10 mi out, the GS will become active.
- At that point your altitude should be LOWER then the GS! i.e.
the vertical needle should point upward.
- Most students then get nervous and try to follow the needle -
that is wrong - wait till the needle gets down into a horizontally
centered position, indicating that you intercepted the GS!
- That is especially important if you use the AutoPilot: If
you activate the GS when you are not already on the GS then the plane may jump upward/downward and you may loose control!!
problem seems to be solved in the newest version of the c172p (higher
than FlightGear 2.0!) - but you better stick to the above procedure to
used to it for other models!)
Start the descent only AFTER the GS-needle crosses the centerline
- from now on you can follow the needle (or activate the Autopilot GS)
- If at that point you are much higher then the GS you
definitely should consider a "GoAround". Because when forcing the
plane down at that point, it might destroy all your nicely balanced
for the "Final" - and you are the first who is (should be) ashamed of yourself!
Remember: It is fun - no emergency or air-show!
Being on "Final" you should notice on your instrument panel 3
signals before "Touch-Down":
As an ATC I hear lots of excuses about a not working ILS etc. - so be
assured that real technical problems are very, very rare (but famous Pilot-errors are not!)
-- so do not be shocked if neither ATC, nor your instructor, nor the
FAA will believe an accident report, based on a technical ILS-problem!
Anyhow: You as pilot are responsible to take over manual if problems
arise! I hope you trained "Landings without Autopilot"!
light and a sound of 400 Hz,
positioned between 4-7 mi out
light and a sound of 1300 Hz,
positioned between 0.5 to 0.8 mi out
Marker: The white
light and a sound of 3000 Hz -
signaling you are over the Touch-Down-Area of the runway!
A final Warning: Most models are not able to do a "Touch Down" with the
Autopilot - so you might want to switch the Autopilot off soon enough,
to have a little time to get a feeling for the controls again!
It is fun and good for exercises, using the ILS - especially without the AutoPilot!
Please find more details e.g. on: http://en.wikipedia.org/wiki/Marker_beacon
The second radio is exactly the same as the first -- but you cannot
use it for controlling the autopilot!!
The Autopilot (AP) shall support the pilot, especially on
long-range flights, by taking over the controls based on predefined
data. The AP can do standard procedures much better then a pilot - but
it has a very limited understanding of the data it is using, and
interprets those data without any intelligence! As an example: If you
program the AP to climb to 10.000 ft it will do that perfectly - but at
an altitude of about 7.000 ft you will crash! Remember from our first
flights? The Mixture has to be adjusted - and the AP does not know
There are thousands of such happenings!
So never forget: You are the Pilot in Command -- not the
Let us see the functions behind all the controls from left to right:
- Switch off
the Autopilot before any "TakeOffs" and "Landings"! Otherwise
you are up for very funny surprises! Even when landing with AP-ILS: Do
switch off prior to Touch-Down!
- Yes, I know: There are models that can do a complete landing (including speed and leveling off - the
Concorde is a perfect example for it!) -- but that are only a
few - and for sure not the Cessna!!
- When you
switch off, switch off the whole device
because it is very difficult to predict which functions will remain
active or become active when you switch off only certain functions
(e.g. the "ROL" will stay active, etc.)
- Remember the delay! The AP
will never switch off at once - it always first blinks some time to
warn you - and then switches Off after that! Try it and notice how long
- AP (Autopilot) switches
the AP-unit on/off.
- When you switch on the AP the very first time, it will read all
the needed status-informations and controls at that time only. The
typical values displayed in the upper line after the initial start:
- "ROL“: The AP keeps the wings leveled
- "VS“: The
"vertical speed" continues active - e.g. the current climb or descent
the wanted cruise altitude is reset to 0 !!
- You should set the wanted altitude as soon as possible!
Otherwise the AP will try to climb to the moon or descent to sea-level!!
- Change that soon - see "ARM" below
- For cruising we will change the AP-settings to show that first line like in the picture
The AP will hold the heading set in the Gyro-Compass
The AP will hold the current altitude
The Altitude to be hold is 5000 ft
Above the AP-button there may show up 2 error-indicators as red letters:
- P: The AP
cannot control the "Pitch" (elevator/trim) - the AP may switch off.
- R: The AP
cannot control the "Rolling" (ailerons) - the AP may switch off
- HDG (Heading) will switch the
upper left indication between "ROL“
just keeps the wings leveled
will turn to and hold the heading defined by the "red bug" in the
Gyro-Compass. When you move the bug the AP will immediately follow that
new setting (even while in transfer!). And it will always take the
shortest way to the new setting. That may result in a
- let us assume you are flying a heading of 000° and ATC
you to "turn left to
- then you probably start turning the red bug to the left to go
to the new heading - and the plane follows turning left
- BUT: You can turn the bug that fast, that there will occur a gap of more
than 180° between the bug and the actual heading achieved
- that means: The plane suddenly turns the other way -
because the initial turn is now greater 180° - thus the other one now
is less than 180° - and thus shorter!
- so when turning more then 180° you must turn in steps smaller
180°. e.g. in this case you first turn the bug left to 190° - and
shortly before the actual heading reaches that 190°continue to move
the bug to the 090°!!
- NAV (Radio-Navigation) switches
to follow the course set in "NAV1“. The AP will then try to intercept
the radial set in the OBS and follow it according to the CDI. You
should be on an course fitting for an interception (<60° deviation
to the radial) - otherwise you cannot be sure if the interception ends
up in the "TO" or "FROM" direction! In any case verify the course after
- APR (Approach) activates the
ILS-Approach - i.e. the Glide-Slope will be activated too (if
- The newest version of the c172p does not require any more to
wait till the GS-needle is horizontally prior to activating the
- But older version (prior 2.0) will need it - for other models
you have to find out yourself (or be careful and just do not activate
the GL too early)
- REV (Reverse) switches to the reverse
of the localizer radial. When you are on APR it will switch off the GL
- ALT (Altitude) activates the
- if the actual altitude is different to the wanted ALT we will
climb or sink as defined by the UP/DN! Did you notice the problem? The
UP/DN is winning! So if you are at 2000 and set the wanted ALT to 4000
ft -- it depends on the UP/DN whether you climb or descent. If in this
case UP/DN is set "-500 ft" you will descent from 2000 ft down do
crash, because you never cross the wanted altitude of 4000 ft!
- clicks on "UP" or "DN" switch into the "VS" mode and increases
or decreases the rate of climb/descent - see the following UP/DN.
- click on the ALT switches the indicated function from "VS“
- There may appear a blinking, vertical written "<PT>"
indication between the displayed "ALT" and "4000" in the above picture.
That is a suggestion to you to trim into the indicated direction. (Remember: The big trim-wheel on the
center-console? Use the keys 7/1 or mouse-wheel over the trim, etc.).
There will be no direct problems if you do not trim - except: As soon
as you switch off the AP the airplane is not trimmed at all - you might
be in for a surprise!
- UP/DN (up/down) increase/decrease
the rate of climb/descent (watch the
negative sign in front of the number - that is often overlooked!)
- As said before: These settings take precedence over the ALT
setting - so there are some very remarkable actions possible
climb to 4000 ft with a rate of 500 fpm
descent to crash
with a rate of -500 fpm
climb until crash
with 500 fpm (or land on the moon)
descent to 2000 ft with -500 fpm
500 then -500
over an obstacle and then return to the set altitude
- ARM activates
the dial below it to preselect the wanted (cruising) altitude.
Use the mouse-wheel or push the left mouse-button to change by 10 ft
each, or the center button (or wheel) for changes in 100 ft each.
Once more 2 points:
- BARO activates
the dial below it to define the barometric pressure.
That "barometric pressure" for the AP is independent of the barometric
pressure set (usually) by the knob at the altimeter!!!
- A blinking display does not indicate an error - it is just the
warning you that a new function has been selected and will be
when switching off the AP it may take some time before
you get back full control. The active settings will be saved for
You find examples for how to use the
Cross-Country" for a " first setup for cruising"
Cross-Country" for "Climbing" and "Cruising" and
There is only one DME for both radios - so you can only watch one
distance at a time - but you may switch between the 2 VORs very fast by
the selector on the left!
- With the switch in the center you switch the unit on/off
- The selector at the left switches between the two NAV-radios N1
and N2 (but
be aware that not every VOR has a DME!)
- the center position "HLD"
stands for “hold”, and means “retain the current frequency, regardless
of whether NAV1 or NAV2 are getting re-tuned”. For example, if we switch from N2
to HLD, the DME will continue to display (and update) the DME-information of
the last NAV-2 setting. Even if we re-tune NAV2, the DME will remain tuned to
e.g. Manteca. This is handy, because it basically represents a third
independent receiver, and on IFR-flights two receivers just never seem to be enough. (see the above ILS-example at EDDF!)
- In the display above "Miles" there is shown the distance to the
- With the white button in the center you select to display on the right either
You find an example of using the DME
in the part "IFR Cross-Country" chapter "SUNO to NDB REIGA"
- the "Speed
above Ground" in KTS
- or the "Minutes"
until you will arrive at the VOR (in case speed and direction remain
As you recall from the previous tutorials, when flying VFR, you don’t
just point your airplane to the nearest runway to land. Even under VFR
you need to fly a pattern. This helps you line up, and helps prevent
planes from crashing into one another, which is a Good Thing.
Similarly with IFR landings. There’s a procedure to follow. In fact,
there are procedures to follow. Because of the complexity of landing in
IFR conditions, there’s no single procedure for all airports. You need
to check for your particular airport. In fact, you usually need to
check for your particular airport, runway, and navigation equipment.
You can find those IAPs where you also find aeronautical informations
for airports, that are e.g.:
- for the USA e.g.:
- http://flightaware.com/resources/airport/KLVK (just change the Airport-ID at the end)
- → "IFR-Diagrams“ = IFR Airport Procedures (/IAP)
- → "ILS Runway 25R“ (the only ILS equipped rw. at KLVK) – this one we need to use
for our IFR approach!
- for Germany e.g.:
- see e.g. for EDDF the "IAC VOR RWY 25R“ etc. ect. - EDDF
has some more procedures than KLVK (yes: There are even more at KJFK,
- but also see that tiny little Sylt (EDXW, e.g. "NDB/DME 14“) (in that same table): Also
that one needs those approaches because of the vacation-guests coming by
air! Of course you also need it to make sure that these
stupid pilots do not always fly over the houses of the V.I.P.s.
- You might want to study this tiny IAP first, in order to
get the general idea!
e.g.: KLVK ILS RWY 25R
During our "IFR Cross-Country" we will
land at Livermore on runway 25R
under IFR conditions. So let us take that one as an example to explain:
Livermore has only two instrument approach procedures, big
airports have many many more. If you look at nearby San Francisco,
you’ll see they have a slew of procedures. There are ILS procedures,
GPS procedures, LDA procedures, VOR procedures, . . . I wouldn’t be
surprised if they had a procedure for someone with a sextant and an
hourglass in there. To learn IFR flight, you’ll need to master all of
them (maybe nowadays you can miss on
the "sextant" - although old captains of the DC6, Superconstallation,
and similar will tell you, that they still had to know how to operate
them, e.g. during Transatlantic Flights!).
For Livermore there are only listed 2 IAPs (e.g. on) http://www.airnav.com/airport/KLVK,
down near the bottom:
Because we want to exercise our ILS-Equipment (and do not have a GPS-equipment)
we use the "ILS RWY 25R":
one is the ILS
(Instrument Landing System)
the other a GPS (Global Positioning System)
approach: Radio-NAV (GPS) RWY 25R
||These Approach-charts are not
really standardized worldwide - but they all contain some common
informations: (Sorry. usually those
are not as nicely colored as seen here!)
together shall give you a 3D view of the IAP. I admit: That is not
really easy to read and understand if you are not a graduated Architect
or Mechanic - but try to use it more often and your
problems will disappear (I hope!).
- In the upper white part you
see general informations like the name, frequencies, etc.
- In the central pink part is the
actual plan, as seen from above, especially for the headings to use
- In the lower yellow part you
see the same from the side, for the altitudes to keep
There are usually a lot more informations at changing locations on the
charts. e.g.: There may be "minimum values" for an approach, e.g.
- You may approach only if there is a minimum visibility,
you have a minimum Radi-Equipment,
etc. (See here in the green box)
"Missed Approach Procedure", i.e. what to do next if you cannot
Touch-Down. (See here in the white box at the top)
per direction you come from, e.g. when on one side are mountains, or
buildings, or so. Those restrictions are in a little circle, cut
into directional pieces. (See
the circle at the right, inside the pink area)
- and an airport-layout.
(See the white box at the left side).
Analyzing the IAP:
First let us find the beginning of the procedure, lucky enough there is
a special mark for it: The IAF (Initial Approach Fix). Looking
into the above pink area we find 2 of those:
- In the center of the pink area you find the LOM/IAF REIGA: This is a NDB with 2 functions:
- As LOM it defines a unique point on the final-approach (we will see/use that later. It is located
6.1 nm out from the Touchdown Area of the runway at an altitude of 1039
ft). Did you find those values?
- "6.1 NM" in the yellow part at the bottom,
- "1039" at the NDB symble in the center of the pink part!
- As IAF
it is the starting point for the IAP.
Based on the NDB it is easy to find: Just set the frequency 374 into
the ADF and follow the needle. Defining the minimum altitude to start
is a little
more complicated, because of the dual function of this point! As
defined here that minimum altitude is 1039 (for the LOM) plus 2409 above that
- At the right center of that pink area you see the second IAF, that one is named TRACY. There is
a "Procedure Turn" attached
to that one - so in real life ATC might send us there to wait, when
much arriving traffic. Finding this one is not that easy - but we
learned how to do that in the chapter" Finding
a FIX-point": Here we would
find it for e.g. a "missed
(see in the white box at the top!) by two VOR-radials:
- 157° FROM VOR "SAC" (SACRAMENTO) on 115.20
- 229° FROM VOR "ECA" (MANTECA) on 116.0
Having found the IAFs we can start following the IAP-procedure:
- We are coming from the south so we will use the IAF nearest to
us: The "IAF REIGA"
- On first sight that looks very easy from there: We just turn left and follow
the localizer to the runway - BUT:
- we are not on the right altitude of 1039 ft as required at that
point (the: LOM)
the IAP shows a big fat line to the right that ends in a line with a
half-arrow pointing to the north-east (marked with 030° and 210°)!
- That means we
have to do a "Procedure Turn" to the right,
away from the airport!
- So we follow the advise of the chart, ending in an ILS approach
- from the NDB REIGA we
follow that fat line on a heading of 075°
- away from the airport (above the
other traffic on final approach!)
- before the outer 10 nm circle (see
the mark in the yellow field, top right) we turn left to a
heading of 030°
- we follow that 030°
while slowly starting to descent to 3300
- after 2 min we turn
right to a heading of 210°
- Now we start a standard
you forgot how-to: See above)
- we stay on 210° until
intercepting the Localizer
I-LVK (heading 255°, frequency 110.5)
- then we follow that localizer while descending to 2800 ft
- and stay on 2800 ft until we intercept the Glideslope for our final descent
- Next we cross our old friend NDB REIGA on
- REIGA is now not our IAF but welcomes us as "Outer Marker" (LOM) with a blinking blue light and a sound of 400 Hz
- and thus we know: We are 6.1
nm before "Touch Down"!
- But you also need to be prepared for a "MISSED APPROACH": If
you look into the upper right corner of the IAP there is a box telling
about a Missed
Approach (Procedure), and
in the lower green part you see the infos to it:
- i.e. for the "S-ILS 25R" you must initiate a "Missed Approach"
if you do not see the runway at an altitude of 597 ft (200 ft above the
Parts of that procedure are shown in several places on the
- at the top, where it says “MISSED APPROACH”
- in the plan view, where
you can see a dashed arrow coming off the end of the runway at the
dashed oval on the right,
- a pattern symbol at the right of the picture
- and a series of boxes at the bottom repeating graphically
what to do.
In our case, these all tell us to:
1. Climb straight ahead to 1100 feet
2. Make a climbing right turn to 3000 feet
3. Fly to REIGA (compare the frequency and Morse-code!)
4. Fly outbound from REIGA at 062◦
5. Fly a holding pattern at the TRACY intersection
The holding pattern, as you might have guessed, is a place where you
can “park” while sorting things out, and has its own set of procedures
and techniques which we won’t go into here, because . . . (but have a look into the chapter "Procedure-Turns" in the part "KnowHow".)
Since FlightGear version 2.4.
"Map" is an integrated part of FlightGear , although it is still in an
experimental mode. (See "menu --> Equipment --> Map").
This current stage of Map covers
especially the "Radio-Navigational" needs, for further informations see
If you have problems understanding those pictures and comments compare
it with the "IFR Cross-Country" flight, and
especially it's "flight-planning"
|You (the yellow plane symbol in the lower right)
just started at KRHV,
now flying on
runway-heading 310° towards the "airway 334", which follows the
Radial "SJC 009",
which we have set before into our NAV-1, and which we will intercept
The next check will be the crossing of the radials "SJC 009" and "OAK
114" (which is set in NAV-2) near the fix "SUNOL", which
is not marked here by name, because
the "Fixes" are not activated (see in the upper left corner!)!
But because "Navaids" are activated you see
» the VORs "OAK" and "SJC" in cyan,
because they are active in your 2 NAV-radios
» e.g. in the lower left quadrant
you see another VOR "OSI" not in cyan
and without Radial, because we do not use it.
" (in the right upper corner)
is the identifier for the NDB
", which is
for our planned approach to KLVK
Because "Traffic" is activated, you see the Multiplayers flying
area. See e.g. "alex" to the left of you and "Godwin" on the dark blue
You should also notice the pointers at those targets:
» "alex" is flying
in direction SW and is relatively fast
» compared to "Godwin", who is
relatively slow on Final to "KSFO runway 28"
|In this picture we changed
already the NAV-2 from "OAK 114" to "ECA 229", and
are on our way from Fix "SUNOL" to the
The two radials cross at fix "SUNOL" - this time its
name is visible because "Fixes" is now activated.
Also activated is "Data", thus we see additional descriptions to the
major navigational aids. See e.g.
» KLVK with the
runways "07L/25R" that are 5236 ft long. The magnetic headings are
with the identifier/morse-code "LV" and
frequency 374 Khz
See also the Fix's "FOOTO"
to which we will turn over "REIGA" on
heading 75°. And also notice that this segment of way is directly
traffic on the ILS towards KLVK - so we better keep a safe altitude.
|In the above we headed for
"REIGA". In the meantime
» we turned to a hdg of 075° over
» which is defined by our course
of 075° and the crossing radial "ECA 229
» there we turned to 030°
» and after 2 Min. we turned 180° to a new heading of 210°, back
towards the ILS-Localizer REIGA
On this heading 210° we are now going to intersect the ILS 25R of KLVK.
notice that that ILS is now in color "cyan"? And the radial "SJC
009" is not shown any more! Sure: We do not need the "SJC 009"
any more and thus switched the NAV1 to the "ILS 25R"!
Also notice that we are close to "TRACY
" - the
" (Initial Approach Fix)
and thus very close to the 10 nm radius, that we were not allowed to