E1-09_Using TACAN_(8.. - e-HAF

87th Stray Dogs
Using Tacan
Introduction
Tacan comes to use when GPS is unservicable, and when bad weather necessitates an instrument
approach, but ILS is not available. In excercising this aid, skill is developed enhancing situational
awareness, based on bearings and headings.
Setup
independend of heading.
Press T-ILS, check TCN TR
is displayed. If not press
SEQ on the DCS. Enter the
frequency. Check the Nav
Selector is in TCN. All set.
TACAN beacon
The Tacan Beacon
gives information
about the radial the
airplane is on. It is
The radials are bearings FROM the beacon. This is important to remember.
We can fly Radials Inbound or Outbound, but the name of the radial is
always the number FROM the beacon. You see right away that it is logical
when you fly a certain radial Inbound that the Course (roughly heading) of
the airplane will be the opposite to that of the name of the radial.
So, if you fly Radial 360 Inbound, your Course will be 180. Passing the
beacon will get you on Radial 180 Outbound. 030 inbound will be course
210, etc etc.
Needles
Let's look at the needles.
This is the technical story, don't look at it for too long !

The trick is Visualization.
Imagine the airplane symbol in the middle displays the TACAN
beacon. Sounds strange, but try. Than imagine the Tail of the
Beacon pointer (red needle) is the airplane, and the airplane is
always flying up. That's actually the heading.
Now it's getting easy.
The airplane is displayed on Radial 060. Again: radial is OUT the
beacon.
The radial 030 is displayed in yellow, and the course selected is
210. If we want to intercept radial 030 Inbound, and continue over that line, you see we will end up on
210 Outbound.
Notice here that when a radial has to be flown Inbound, it is the Tail of the yellow needle. The point of
the yellow needle is for the Outbound radial, so you could say radial 210 Outbound is selected here as
well.
If you want to make a mental map of how the situation is on a
north-orientated map, you can, but you don't have to. Here's how it
would look:
Example Radial 340 Outbound
Lets see how this works. The departure route says Radial 340 Outbound
untill 18 NM. Outbound, so the course is going to be 340 as well. And
when established, 340 will be the heading, corrected for wind.

Start situation. Look at the HSI
and as yourself where you are,
where the radial is and how to
attack that radial.
The Visualization. Check ownship is at
Radial 090 flying on heading 025.
Apparently an intercept would start
with a left turn.
The mapview. North
is up.
This is how it looks when we first
fly heading 340.
Now continuing on heading A (340)
won't get that Red tail towards that
radial in a fast way. It will look close,
but never on it.....B is an attack
heading of 45 degrees towards that
radial.
To attack the radial on 45 degrees, just
put it under the tickmark. While our
little airplane flies up, it will drag that
red-tail towards the radial.

Almost there. Turn 340 and ready.
Visualization of being quite close to
the radial
Stabilized. Now follow the yellow
Course Deviation Marker while
correcting for wind.
Now let's look at Intercept of Radial 030 Inbound.
At each stage, practice visualizing the Airplanesymbol as the Tacan Beacon,
the Tail of the Red Beacon Pointer as ownship, flying up, pulling that needle along...
Where are we ? At Radial 059
Heading 075, 030 Inbound, so
Course 210 selected.
Notice that the desired radial is the
Tail of the Yellow Needle when
Inbound is requested.
Red tail will have to be pulled to the
left, to get on the 030, than left
again. Visualization here.Looks like
we have to make a left turn. 90
degrees onto the radial.
Mapview. Shouldn't
need it though.

stabilized.
Wondering about 030 Outbound ? Well, a right turn at the last phase instead of a left turn would have
done it.
Time for something more difficult
Now a different situation, where we have to fly past the beacon first. Good oppurtunity to show you
how it works when you imagine the airplane is a Red Tail and the airplane symbol the beacon.
Intercept Radial 270 Inbound
Let us intercept R270 Inbound,so Course will be 090. Check the circled location of the desired radial.
Red Tail sais we are on R 070, and we
have to find a way to pull the Red Tail
towards the Yellow tail. Imagine we are
the Red Tail, the airplane symbol is the
beacon, the Radial is yellow.
Visualization:

The Plan !
The start of a good plan.
We are flying parallel to the radial, but
our Red Tail is pulled up. Again
imagine the airplane symbol is the
beacon and we are at the end of the Red
Tail.
14 NM right abeam the beacon.
Free to choose when to turn in,
depending on the length of the inbound
leg you want.
Not sure ? Visualize that airplane
symbol and Tacan symbol again. See
how it matches the map view.
Around 18 miles seems good for now.
Put the Yellow Needle at the 90 degree
tickmarks untill the Deviation Marker
starts to move inwards. Again the Red
Tail is pulled upwards, and as
advertised, towards the Yellow Tail.

Endgame. Small left turn and we are on
the Radial 270, Inbound, thus flying
heading 090.
See ? Easy....
By (v)cpt. Gerben "Coffin" Verrips
dec. 29, 2004
This article comes from 87th Stray Dogs
http://www.87th.org
The URL for this story is:
http://www.87th.org/modules.php?name=Sections&op=viewarticle&artid=35