Transcript CAPR 60-series Review slides

Authored by Rich Simerson 01-Jun-2007
Modified by Lt Colonel Fred Blundell
TX-129 Fort Worth Senior Squadron
For Local Training Rev 5.0 03-Jan-2014
This Training Slide Show is a project undertaken by Lt Colonel Fred
Blundell of the TX-129 Fort Worth Senior Squadron, Fort Worth, TX for
local use to assist those CAP Members interested in advancing their skills.
The information contained herein is for CAP Member’s personal use and is
not intended to replace or be a substitute for any of the CAP National
Training Programs. Users should review the presentation’s Revision
Number at the end of each file name to ensure that they have the most
current publication.
2
Objectives

Discuss the various types of ELTs. (O)

Describe how an ELT can be detected. (O)


3
Describe how the aircraft DF works in both the Alarm and DF
modes. (O)
Discuss using the DF during a typical ELT search (O)
• Response during initial phase, including signal fade
• Response when getting close
• Response as you pass over the beacon
Objectives
(Continued)



4
Describe the following ELT search methods: (O)
• Homing
• Wing null
• Aural
• Signal
Discuss signal reflection and interference. (O)
Describe how to silence an ELT and the legal issues
involved. (O)
Emergency Locator
Transmitter
Direction Finding for Aircrews
Use Of Equipment Commonly Found In CAP Aircraft
5
Objective
the Elusive ELT



6
Automatic radio beacon (100 milliwatts)
• Roughly equal to that of a regular flashlight
Can be heard on a line-of-sight basis
Remember that the ELT may be attached to an
aircraft or vessel in distress!
The ELT



7
Activated by g-force (when armed)
• Some can be activated by the pilot in the cockpit
Three frequencies:
• 121.5 MHz (VHF emergency)
• 243 MHz (UHF emergency – military guard)
• 406.025 MHz (third generation advanced
ELT/EPIRB/PLB)
General types:
• General aviation aircraft
• Military (“beepers” or “beacons”)
• Marine EPIRB
• Test station (training practice beacon)
• Advanced (406)
ELT Aircraft Antenna
8
Most Aircraft Have
ELTs Installed
But they
don’t always
survive a
crash
9
Most Aircraft Have
ELTs Installed
But they
don’t always
survive a
crash
10
Military Beacons

Most common type is the URT-33/C

Personnel ejecting/parachuting will have a 243 MHz beacon

11
Some downed pilots may be able to communicate via twoway radio on 243 MHz using a PRC-90 or later military
survival radio
• Beacon mode transmits like an ELT on 243 MHz
Personal Beacons

12
Personal Locator Beacon (PLB) or Personal Emergency
Transmitter (PET):
• Intended for hikers and other remote wilderness travelers
• Use a 406 MHz transmitter and a 121.5 MHz homing signal
(at only 25 milliwatts)
• Many are also equipped with a built-in GPS receiver that
provides lat/long coordinates
• Each PLB must be registered
• [See discussion of Advanced ELTs]
Marine EPIRB




13
Emergency Position Indicating Radio Beacon
Similar to an ELT, an EPIRB is used on ships and
boats
Mandatory on certain commercial vessels
Some activate automatically and others are manually
activated
Advanced ELTs

Designed to operate with SARSAT/COSPAS
• 406.025 MHz beacons have data burst encoding that
identifies each (registered) individual beacon
• Also produces a 121.5 MHz homing signal and may
transmit GPS coordinates
• Sends a coded signal that can be used to obtain the
owner's name, address and type of aircraft, so AFRCC can
call the number to see if the aircraft is really missing
(70% resolved)
14
Advanced ELTs
(Continued)
• Since geostationary satellites process the signal it will be
heard more quickly and allow a much faster response (~ 6
hours). If the unit has a GPS receiver, it can transmit lat/long
coordinates to further speed the search. The signal can also
penetrate dense cover (e.g., trees)
• Still very expensive (~ three times as much as a 121.5 MHz
ELT)
15
Practice Beacon




16
Training Practice Beacons
• Includes ones used by CAP
All should be converted from 121.6 to 121.775 MHz by now (if
it isn’t, don’t use it)
During practice searches, avoid calling the practice beacon an
‘ELT’ when communicating over the radio
• May cause confusion
Always use the term ‘Practice Beacon’
Testing an Aircraft ELT


Only allowed up to three sweeps

When was the last time you tested the ELT in your aircraft?

17
Can test the aircraft’s ELT within the first five minutes after
each hour
Do you regularly monitor 121.5 MHz after you land?
• Ensure your ELT didn’t activate
• This isn’t considered a test, by the way, but you can try
this excuse if you like
Inadvertent Activation

Excessively hard landings (Welcome aboard, Ensign!)

Inadvertent change of switch position

During removal/installation

Malfunction


18
Non-ELT source on 121.5 MHz (computers, broadcast
stations, even pizza ovens!)
Monsieur Murphy
False Alarms


19
Approximately 97% of received ELT signals are false alarms
• For 121.5 MHz ELTs abut 1 in 1000 are actual emergencies
(2 in 100 composite alerts)
• For 406 MHz ELTs abut 1 in 10 are actual emergencies
What’s the big deal?
• SARSAT can only monitor 10 ELTs at once
• Easy to overload the system
• They block emergency communications on 121.5 and 243 MHz
(guarded by towers, ARTCC, and the military)
20
Detection Timeline
21
Accuracy of
SARSAT/COSPAS



22
For a regular 121.5 MHz beacon:
• Said to be a 12-16 nautical mile radius (~ 452 square nm)
• Actually an oval shape with a 50% probability of being 15
nm wide and 7 nm high
• System is more accurate North to South (latitude)
• Average six-hour detection/alert
For a 406 MHz beacon it’s a 1-3 nm radius (~ 12.4 square
nm) with 45 – 60 minute detection/alert
For a 406 MHz beacon with GPS it’s a 0.05 nm radius (within
100 yards) with an average five-minute detection/alert
So how should
I treat an ELT Mission?




23
AS AN EMERGENCY!
Its not possible to know whether an ELT signal is a distress
signal or a false alarm
Although the statistics are against it, you must act as though
it is a distress call
If you take advantage of them, every ELT mission allow you
to keep your skills sharp!
Locating
the ELT Signal



24
Route or parallel track to pick up the signal
If no SARSAT hits or definitive LKP:
• 4,000 to 10,000 AGL
• Large track spacing (start at 60 nm, then do
halves)
Once signal is located, DF the signal
Direction Finder (DF)
• A direction finder compares signal strengths from two antenna
patterns to let the user know:
 When you are “centered” on a signal
• headed directly towards OR away from the signal source


25
Which direction to turn when not centered
Similar to an ADF needle, but only points left or right, hence
the term “left-right homing”
L - Tronics DF


26
Normal: Alarm toggle in ‘up’
position
DF: toggle is ‘down’
DF Antenna
These are mounted on the bottom, but may be on top.
27
Step 1
Acquire the Signal



28
To hear the signal you can use your L-Tronics receiver or
one of your comm radios
To acquire with a comm radio, turn the squelch OFF (pull
out the volume knob out or flip the appropriate switch)
• The static you hear may be annoying, but it will allow
you to hear the signal at the earliest possible time
• Allows for a weak or distant signal to be heard
Proceed at a reasonable altitude to the SARSAT
composite hit, or to the point designated by your
incident commander
Beginning the Search
Altitude Selection
Higher altitudes allow for reception of the ELT signal at greater
distances

ELTs transmit on 121.5 MHz and 243.0 MHz, both of which limit
reception to “line of sight”


Terrain will block ELT signals

HIGHER is therefore usually BETTER to acquire a signal
Medium altitude is generally better for searching (after signal heard)
- 3,000 to 5,000 AGL

NO
SIGNAL
29
SIGNAL
HEARD!
ELT
NO
SIGNAL
Altitude Selection
EL
45 00 0
L40 00 0
G
35 00 0
A
t
e 30 00 0
e
F
, 25 00 0
E20 00 0
D
U
15 00 0
T
I
T10 00 0
L
A 50 00
0
30
Intersection Area
Step 2
Track (DF) the Signal

32
There are many different ways to DF an ELT
signal:
• Left-Right DF Homing (L-Tronics DF)
• Wing Shadow Method
• Aural Search
• Metered Search
• Combinations of the above techniques
Wing Shadowing


33
By flying the airplane in a circle, at some point the wing will block
the ELT signal to the receiver antenna
• This causes an audible decrease in volume, called a “null”
Almost any VHF-AM aircraft communications radio may be used
with this method
Wing Shadowing
Antennas



34
To properly use the Wing Shadowing method, you MUST know
where the antenna for the radio you are using is installed &
located on the aircraft
Communications radio antennas are usually, but not always,
located above the wings
• Can be above the fuselage, in the tail, etc.
L-Tronics Aircraft DF antennas may be above or below the
aircraft
• Below the aircraft is the preferred installation
Communications
Antennas Above the Wing
Antennas Above
the Wing
35
DF Antennas
Below the Wing
Antennas Below
the Wing
36
How to DF
by Wing Shadowing
N

E

W

Fly a constant bank angle 360°
turn
the audio will “null,”
or get significantly quieter,
when your wing blocks the
antenna’s reception of the
ELT signal
S

37
Wing Shadowing-Signal Blocking
For Antennas Above the Wings
NULL
NULL
NULL
SIGNAL
ELT
38
Wing Shadowing
Antennas Above the Wing



Turn in a circle until you hear the null (significant
decrease in volume)
The ELT is 90º to your LEFT
SUBTRACT 90º from your
heading
ELT
39
Wing Shadowing-Signal Blocking
For Antennas Below the Wings
NULL
NULL
SIGNAL
ELT
40
Wing Shadowing
Antennas Below the Wing


Turn in a circle until you hear the null (significant
decrease in volume)
The ELT is 90º to your RIGHT: ADD 90º to your
heading
ELT
41
Aural (Hearing)
Search Method
This is based on the assumption that the area of equal beacon signal
strength is circular: do NOT adjust volume during this search; you
will need it to determine equal levels of signal

Begin by plotting your position as soon as you receive the ELT signal

Fly that course for a short distance, then turn 90º left or right and
proceed until the signal fades

Turn around (180º) and mark where the signal fades on the other
side of the circle


Plot chord lines similar to that of the diagram

Bisect the chord lines at a perpendicular
Plot a course to the location where the perpendicular lines intersect:
this should be the location of the target!

42
Aural Search
Equal signal strength circle:
barely audible signal in aircraft
receiver at search altitude
ELT
SIGNAL
HEARD
SIGNAL
FADES
chord 2
SIGNAL
HEARD
SIGNAL
FADES
SIGNAL
HEARD
43
Metered Search
Build & Fade Method





This search requires a signal strength meter (like that on the L-Tronics
DF units-if the DF portion of the unit is inoperative you can still use
this type of search as long as RECeive is OK
Note your signal strength when beginning the search
Fly a straight line until the signal gets lower, then increases to your
original level
Turn 180º and return to the lowest level of signal, then turn 90º left or
right
You should now be headed directly towards or away from the
transmitter

If the signal increases in strength, you are headed directly for the ELT

If the signal decreases in strength, turn 180º
44
Metered Search
3
ELT
2
MAXIMUM SIGNAL
THEN DROP
6
4
5
1
45
FIRST SIGNAL
Left-Right DF Homing


46
Most CAP corporate aircraft have L-Tronics LA-Series
Left-Right Homing DF units
These units operate virtually the same, but there are
two major varieties:
• Single Meter Models
• Dual Meter Models
L - Tronics DF Types
Single Meter Model
m SENS
REC
243
ALARM
AUX
121.775
VOL
DF
121.6
VHF-DF
121.5
OFF
L-Tronics
Dual Meter Model
DF
ALARM
STRENGTH
m SENS
VOL
243
121.775
AUX
121.6
121.5
47
VHF
DF
OFF
L-Tronics
Frequency Switch

Selects frequency to be used

Use 121.5 MHz for actual ELTs/EPIRBs

243.0 MHz may also be used for all actual electronic
searches

Use 121.775 MHz for training

Refer to owners manual for use of the “AUX” position
m SENS
REC
243
121.775
ALARM
AUX
VOL
DF
121.6
121.5
VHF-DF
OFF
L-Tronics
48
Mode Switch
Only Single-meter units have this switch
• Dual-meter units use two displays, so both REC and DF operate
continuously and simultaneously

REC is short for RECeive mode
• REC makes the unit’s dial work as a strength meter

DF is short for Direction Find
• DF gives left-right homing to the ELT/EPIRB signal

ALARM is for NON-MISSION flights only
• Use only during normal flying to alert the presence of an ELT or
EPIRB

m SENS
REC
243
121.775
ALARM
AUX
VOL
DF
121.6
121.5
49
VHF-DF
OFF
L-Tronics
Volume & Sensitivity



Volume controls the audio level to the speaker or headsets
Sensitivity controls the amount of signal that enters into the DF unit
• It is critical that the proper amount of signal enters the DF: halfscale, or the middle, is an optimum starting place
As the signal gets stronger, reduce SENSITIVITY, not volume
• The DF will be unreliable as too much signal is received, so you
must cut out part of it by reducing the sensitivity
• More than three-quarters scale is too much
DF
ALARM
STRENGTH
m SENS
VOL
243
121.775
AUX
121.6
50 121.5
VHF
DF
OFF
L-Tronics
DF Settings For
Single Meter Models


51
MISSIONS
• Select 121.5 (or 121.775 for training missions)
• Select DF Mode
• Turn Sensitivity to Maximum (Full Clockwise)
• Turn Volume to About Mid-Scale
• DF Needle Will Move Slightly Left and Right
NON-MISSION FLIGHTS
• Select 121.5
• Select Alarm Mode
• Turn Sensitivity To Maximum
DF Settings For
Dual Meter Models


52
MISSIONS
• Select 121.5 (or 121.775 for training missions)
• Ensure Alarm Toggle Off
• Turn Sensitivity to Maximum (Full Clockwise)
• Turn Volume to About Mid-Scale
• DF Should Stay About Centered
• Strength Meter Will Move Up-Scale to Right
NON-MISSION FLIGHTS
• Select 121.5
• Turn Alarm Toggle On
• Turn Sensitivity To Maximum
Pre-Flight
Functional Check


53
Just as you pre-flight the rest of the aircraft, you
should preflight your DF when going on an ELT
electronic search mission
These procedures are covered in the Mission Aircrew
Reference Text.
Six Steps



54
Use these 6 steps for locating ELTs and EPIRBs with LTronics LA- series airborne DF equipment
Use the full procedure every time for the best results
• RECeive
• HALF
• DF
• TURN
• CHECK
• SHOOT
Each of these steps will be described in detail in the
slides to follow
Step 1 - RECeive



55
Once you have started to receive the ELT or EPIRB signal
on the proper frequency
If you have a single-meter unit, turn the mode selector
to RECeive and turn the volume to a comfortable level
If you have a dual meter unit, refer to the STRENGTH
window (no need to change modes)
RECeive
Mode/Strength Window



56
In receive mode or in the strength window, the unit measures
signal strength
• Needle to the left means low; to the right means high
Values are relative depending on the sensitivity you have selected
You may still be able to use the strength meter even if the DF is
not functioning perfectly
• It is possible to locate an ELT using only the Receive Mode
• Utilize Aural Search/Metered Search methods to accomplish
• If the unit isn’t completely operable, try wing shadowing using
one of the aircraft’s communications radios and use the DF
unit’s strength meter as a backup using the aural/metered
methods
Step 2: Half




57
Now that the unit is in RECeive mode and you have a
good signal, turn the Sensitivity Knob to HALF SCALE
• This is in the center of the window
If you are flying with a dual-meter unit, turn the
Sensitivity Knob so the needle reads HALF SCALE in the
STRENGTH window
A half-scale strength reading will prevent too much
signal (over sense) from entering the unit and will
provide you with a good starting point
It is also the optimum for the DF homing antennas
Step 3: DF



58
For single-meter units, turn the mode selector knob to
DF
In DF mode, you can think of the needle as always
pointing Direct to the Flipping target.
For dual-meter models, simply refer to the DF window
(no need to change modes)
A Direction Finding
Primer Antenna Theory



Antennas can be more or less directional depending on
their design
Imagine a car radio antenna: it is unidirectional
• Its pattern looks like the one on the left
A Satellite Dish is highly directional
• It would have a pattern like the one on the right
car radio
antenna
(monopole)
satellite dish (parabolic reflector)
DF Antenna


The aircraft DF unit has a 2 or 3 “element” antenna
• Commonly, we might call this two or three antennas
• It just means there are two or three rods!
This antenna setup is directional
• One element actually receives the signal
• The other elements (rods) reflect the signal away from the
first rod
Antenna Elements
60
Antenna
Reception Pattern


When viewed from the bottom, an antenna setup like the
one pictured on the previous slide produces a reception
pattern like the one shown here
• This pattern is called “carotid,”
which means
“heart-shaped”
The pattern is the same
even if the antennas are
mounted above the
wing
Element 1
61
2
3
DF Unit Antenna Pattern
REFLECTOR
ELEMENTS
TOP VIEW
DIRECTIONAL
ANTENNA
PATTERN
RECEIVING
ELEMENT
AIRCRAFT VIEW
Direction
Finding Mode/Window





The DF mode rapidly alternates the
receiving and reflecting antenna elements
• It chooses one element as the
receiver and the other two as the
reflectors, then switches to the other
set
This produces a carotid pattern each time
the unit switches
• one is shown in blue, the other in
yellow
By comparing the two patterns, the unit
will determine when they are equal
When they’re equal, the needle centers!
When the needle is centered,
the target is either directly ahead or
behind you!
63
Step 4: Turn



64
Turn at least one FULL circle, noting where the DF
needle centers
Under ideal conditions, the needle will center twice
• When facing directly at the source of the signal
• When facing 180º away from the target
You will solve this problem (called ambiguity) in the
next step
DF Centers
ELT (Possibility 1)
Alternating
Antenna
Patterns
When The Patterns
Are Equal, The DF
Needle Centers!
Alternating
Antenna
Patterns
65
ELT (Possibility 2)
Step 5: Check



66
Use Turn to Tell
Remembering that in DF mode the needle always points
Direct to the Flipping target
When you have the needle centered, turn left or right
• If you turn left and the needle goes left, the ELT is
180º from your present heading
• If you turn left and the needle turns right, the ELT is
dead ahead
Ambiguity




ELT (Possibility 1)
When Needle Centers
• ELT is Directly
Ahead or Behind
This situation is
called “ambiguity”
To Solve
ambiguity:
Use Turn to Tell
• Make a turn left or
right
• The needle always
points
Direct to the
Flipping Target
(DF!)
67
ELT (Possibility 2)
DF Needle



Compare the YELLOW (LEFT)
and the BLUE (RIGHT)
antenna patterns
In this case, the
LEFT pattern is
stronger than
the RIGHT
In DF mode, the
needle would then
point LEFT
• The needle always points
Direct to the Flipping
Target!
68
ELT
Solving
Ambiguity


ELT (Possibility 1)
Actual ELT position
is unknown to user
Make a small turn
left or right
• As a teaching
reminder, “Use a
TURN to TELL”
69
ELT (Possibility 2)
Solving
Ambiguity



ELT (Possibility 1)
Actual ELT position
is unknown to user
Make a small turn
left or right
• As a teaching
reminder, “Use a
TURN to TELL”
Example:
• TURN LEFT
• needle goes left
70
ELT (Possibility 2)
Solving
Ambiguity



Actual ELT position
is unknown to user
Make a small turn
left or right
• As a teaching
reminder, “Use a
TURN to TELL”
Example:
• TURN LEFT
• If needle goes left
• ELT is to your left
(behind you)
71
ELT (Possibility 2)
Solving
Ambiguity


ELT (Possibility 1)
If you turn Left and the
needle moves Right
The ELT is in
Front of you!
72
ELT (Possibility 2)
Solving
Ambiguity



ELT (Possibility 1)
If you turn Left and the
needle moves Right
The ELT is in
Front of you!
Example:
• Turn left
• Needle goes
right
73
ELT (Possibility 2)
Solving
Ambiguity

Solution:
• If you turn Left
and the needle
moves Right
• The ELT is in
Front of you!
74
ELT (Possibility 1)
Step 6: Shoot


You may need to fly through a
zone of signal dropout
S

Use your DG to determine a
bearing to the target & follow it
E

W
N
Be watchful for signs of signal passage
• If you get signal passage, consider using the “pinpointing the
target” techniques listed in this presentation
Frequently repeat the full six steps to ensure you are heading in
the right direction and that you didn’t inadvertently over fly the
ELT
75
How an L - Tronics DF
Unit Works
-Summary



76
Two Main Modes of Operation
• RECeive
• DF
RECeive Mode is a Strength Meter
• Left is low, right is high
DF Mode Centers on Signal
• Always points to the signal
• Use a Turn to Tell when solving ambiguity
Aircraft and ground units work the same way
Reflections



77
Reflections of an ELT signal work just like a
flashlight off of a mirror
Any flat, hard, or wet object can cause signal
reflections
• Mountains, especially cliff faces
• Hangars and other metal structures
• Wet grass or snow
• Large bodies of water or ice
Power lines can also have a large effect on a lowpowered signal such as an ELT
Beating Reflections
Check your sensitivity at half-scale or lower
• But ensure that its high enough to receive adequate signal

Reflections will generally be weaker than the most direct path to the
target

Following reflections will generally take your closer to the target

If sensitivity is set to minimum, try DFing on a different frequency
• For example, if you are trying to locate an actual ELT on 121.5
MHz, try locating it on 121.6 or 121.775 MHz when you get close

When all else fails, fly somewhere else to get a good DF bearing-or
try that at the first sign of problems!

78
Beating Reflections
• You don’t always need to hear the ELT or EPIRB to find it
• A carrier-only signal may be broadcasting with no audible
sweep
• This is especially true with low or old batteries, damaged ELTs,
or spurious transmissions
• You can identify a carrier-only signal by DEFLECTION
• If it looks like you’re finding an ELT, even if you can’t hear it, you
have good DEFLECTION
• Good needle deflection generally indicates a signal that is strong
enough to DF
Carrier-Only Signals
• You don’t always need to hear the ELT or EPIRB to find it
 A carrier-only signal may be broadcasting with no audible
sweep
• This is especially true with low or old batteries, damaged
ELTs, or spurious transmissions
• You can identify a carrier-only signal by DEFLECTION
• Good needle deflection generally indicates a signal that is
strong enough to DF
80
Carrier-Only Signals
• Compare your deflection to another frequency
 If you are using 121.5 MHz, try it on 121.775 MHz
• If deflection is the same in both frequencies, you DON’T have
a signal, just random noise
• If deflection is different, keep at it! You have the signal
• If a signal is only received on 243 MHz, it may be a
malfunctioning antenna (e.g., an FAA tower). If you DF to the
location (particularly on or near an airport) and you keep
ending up at an antenna, investigate. Find out who owns the
antenna and its purpose. Inform the IC and let the controlling
agency troubleshoot the problem.
81
Vertical Reflections
and Signal Dropout





82
The transmission pattern (similar to the reception
pattern of the DF antennas, only for transmission) of an
ELT is not a perfect circle or sphere
It has lobes, or, stronger and weaker points
This is accentuated when the ELT is transmitting from a
location above the surrounding ground
When you get a good DF heading and the signal fades or
drops out completely you may just be outside of one of
the signal lobes
When you reacquire the signal, it should be stronger
than when you lost it
Signal Dropout



If you encounter a signal dropout, continue to fly on your last good DF
heading
You should reacquire the signal in a few minutes
• Actual time will depend upon your distance to the target
If you are unable to reacquire, return to where you last heard the signal
and re-DF
NO SIGNAL
SIGNAL
HEARD
83
Signal Strength



The rate of change in signal strength increases as you get closer to the
transmitter, and RECeive mode or the STRENGTH window measures
signal strength
This is due to Maxwell’s inverse square law:
• When you double the distance from an object, the energy it you
receive from it is 1/4 of what you originally received, or the inverse
square: 1/(22) = 1/4
 After Scottish Physicist James Clerk Maxwell, 1831-1879
You will therefore need to turn down the sensitivity to keep the unit at
half scale in the RECeive mode or STRENGTH window much more often
as you get close to the source of the signal
• This should let you know that you’re getting close
84
Signal Strength
Rate of Change
m SENS
3
2
1
85
4
VOL
5
6
7
1
2
4
8
16
32
64
“Cone of Confusion”



86
Antennas receive best when the
pole is perpendicular to the signal
When you approach the directly
overhead position on an ELT, your
DF will become unreliable
• It may swing left and right
• It may center regardless of your heading
You should practice to see what this
“station passage” reading looks like
• It is similar to crossing a VOR
Cone of
Confusion
Reception in the “Cone of Silence”


You may also get a significant drop in ELT signal since the antennas
don’t receive well directly off of their tips
Although called a cone of silence, you will probably only see & hear a
large decrease in signal instead of complete silence
POOR
antenna
signal
87
GOOD
Pinpointing the ELT



If you get a station passage indication, make an approximate 180
degree turn and DF back to the target
Repeat this process using different approach angles
each time, remembering that
your path may be curved due
to wind (like uncorrected
NDB holding)
The point where station
passage is received
several times
should be the
location of
the target
2
3
1
88
Pinpointing the ELT


89
After you think you have the target located
• make a low pass over the suspected location and
visually scan
• if signal strength decreases significantly or drops out,
climb back and try again
• this is not the target: sometimes false targets will
appear due to reflections or other interference
If you hear the ELT at low altitude, you probably have
the right place
• a low pass down a runway might be a good idea if
you suspect a particular airport
Becker SAR-DF 517





Completely different theory of operation
from L-Tronics DF
• Pseudo Doppler Shift
• Beyond the scope of this course
• The advanced ELT course has an
explanation
Easy to use
Displays a delayed average heading to
the beacon
Can be used on 121.5, 243.0, or
406.025 MHz
Able to process newest ELTs, EPIRBs, &
PLBs
Becker Operation







Power
Mode
Page
Tune
Squelch
DF
Locate
Power



POWER Press the
ON/OFF button—unit
should power up and
illuminate
Be prepared to execute
the next steps…
If you’re not fast enough,
you may need to recycle
power (turn it off and
back on)
Mode

MODE Using the PAGE knob (upper
right knob), select:
• EMERGENCY for an actual SAR or
• TRAINING for a training mission
• This setting can only be changed on
power up




Recycle power to change the Mode
After setting EMERGENCY or TRAINING,
just WAIT until the unit automatically
goes to the next page
The “wait time” is about 15 seconds
Don’t push any buttons or turn any
knobs during this period
Page

Use the PAGE knob to cycle to desired page

Page 1 is most like an ADF

Page 2 is good for forward quarter only

Page 3 is most easily read by the entire crew, but only in
relative bearing
Tuning







The lower-right +/- knob changes the
frequency
You want 121,500 for an actual SAR or
121,775 for training
You can alternately use 243,000 or
243,550 respectively
You will only be able to select training
frequencies while in the training mode
Similarly, you can only select actual SAR
frequencies in the emergency mode
156,800 is for Marine Band Channel 16
EPIRBs
Notice the commas: the Becker is made in
Europe; the commas replace a decimal
point
Squelch

Squelch Knob




Squelch Setting Triangle
Ambient Noise Level


Adjust the squelch knob on the upper left
of the unit
The squelch knob may be marked SQL or
DIM (depending when your Becker was
made)
Adjust the small triangle arrow until it is
pointing barely above the solid bar
The solid bar represents static or
ambient noise, but you will want to listen
and make sure that the “static” is not
actually a signal
When trying to acquire a signal, you may
want the squelch all the way down
You may also want to do this to make
sure you can hear audio from the Becker
Turn the lower left knob to adjust the
volume to a comfortable listening level
Direction Finding (DF)











Follow the relative bearings to the ELT
Use homing procedures like an ADF
Correct for strong winds, if known
Remember that these are RELATIVE bearings with the
nose of the aircraft being 360°/ 000° !!!
If you are showing a >006> that means turn right 6°
If the unit shows <354<, then turn LEFT 6°
This is similar to a fixed-card ADF
“Rub The Tub” RB + TH = TB
Relative Bearing + True Heading = True Bearing
This is also true if we replace magnetic bearing and
heading instead of the trues: RB + MH = MB
Therefore if the Becker DF indicates >010> and you are
flying a 270° heading, the magnetic bearing of the ELT is
280°. Add right, subtract left.
Becker Direction
Finding Notes
DARK MARBLE


>020>
CLEAR MARBLES

The clear marbles indicate when the Becker first and last
receives the ELT signal in its circle
Watching the clear marbles will give you an indication of
how coherent your DF solution is
• The marbles will always jump around; if they jump
around a LOT you don’t have a good DF
• You can test this by seeing what your indications are
when you reduce the squelch enough to “DF” static
• The clear marbles will jump all over the place
• Static can sometimes look like a carrier-only signal
The dark marble should be fairly stable on an actual
signal because of signal-averaging software
Locate

After flying over the ELT, you should get a “station
passage” indication

Turn around and re-DF to locate the target

This is similar to locating with the L-Tronics DF


If you keep the signal at 090 or 270, you can fly a “turn
around a point” using the DF
If the target isn’t visually significant, this will give your
Scanner(s) the opportunity to put eyes on the target
Bearing on more than
One Transmitter






If bearing from a long distance, the DF will be
pointing at the middle of the two transmitters
This is because the Becker averages the
signals it gets
Exactly in the middle between two
transmitters, the DF will display an unusable
bearing value
The clear marbles will swing WIDE (180
degrees or more) when in the middle of 2
averaged signals
Exactly over one transmitter the DF will be
pointing to another (garbling cone)
Tactic for this situation: don’t fly the approach
exactly following the indicated averaged
bearing: fly about 20 degrees left or right
Becker Thoughts




The Becker unit is not as sensitive as the L-Tronics DF, so you must
be significantly closer to the ELT to get initial signal
Because it uses averaging functions, it will not instantaneously point
to an ELT like the L-Tronics unit—there is definitely a delayed
reaction
The displays on the Becker lead you to believe that it is a pseudoRMI or ADF type pointer. This is not the case. Even when the
complete circle (page 1) is displayed, the arrow only indicates left or
right, NOT how much (such as an ADF). The same is true for the
“pie” display, page 2
Look to the “dark marble” to indicate the relative direction of the
signal; this acts as an ADF-type pointer
Becker Thoughts




Look to the “dark marble” to indicate the relative direction of the
signal; this acts as an ADF-type pointer
If you do not have an operable training beacon to practice with, pick
an AWOS, ASOS, or other continuously-transmitting source that is
within the training frequency range. If you tune it in (see the
manual, training mode only) you can DF it. A caution with this
method, however, is that an AWOS transmits at least 250 times the
power level of an ELT. This makes DFing an AWOS much easier than
an ELT
Be careful with the unit as it costs roughly $10,000. MAKE SURE
THE UNIT IS OFF DURING ENGINE START/SHUTDOWN. Some
installations have the DF independent of the avionics master and the
unit is sensitive to surges from start/shutdown.
The complete user manual is available at http://www.beckerusa.com
After Locating
the ELT



After location, coordinate with ground teams to bring
them on-scene
Use radio communication and relay GPS coordinates
Pick up the ground team at a predetermined location and
lead them to the target

Alternately, coordinate a pick up point on the radio

Practice your air-to-ground coordination skills often
• try it both with and without radio communication

103
Air-to-ground is CAP’s best unique ES skill!
DF Upon Landing


You can use a hand-held radio or hand-held DF unit

The most commonly used in CAP is the Little L-Per

104
Many times the ELT is located at an airfield where it is easier
for you to land and locate the ELT than it is to get a ground
team to the scene
You did remember to put one of these (with charged
batteries) in the aircraft before you left, didn’t you?
Little L - Per

Six Steps
• Receive
• Half
• DF
• Center
• Turn
• Shoot
105
Which of these
planes is it in?

You land at an airport with multiple hangars and each hangar
is full of aircraft

This can make it difficult to find the ELT

Two methods can help:
• Signal-offset
• Using a hand-held radio without its antenna

106
If the suspect aircraft has an external DF antenna and you
can’t get inside to turn the ELT off, try placing an aluminum
foil ‘sleeve’ over the antenna to see if the signal strength
decreases significantly
Which of these
planes is it in?
(Continued)

Signal-offset: reflected signals are generally weaker so by
tuning your radio further away from the primary frequency
you can isolate the signal:
• Assume ELT transmitting on 121.5; set to 121.55
• As you home in set in 121.6 (you may even work up to
121.7)
• As you get further away from 121.5 the area where the
signal will break through the squelch becomes smaller and
smaller (you can even turn up the squelch to get further
isolation)
107
Which of these
planes is it in?
(Continued)

Using a hand-held radio without its antenna:
• Once you’ve narrowed the suspects down to one or two
aircraft (usually side-by-side), remove the radio’s antenna
and hold it next to one of the ELT antennas
• Turn the volume down until you just hear the signal
• Don’t key the radio’s transmitter with the antenna
removed!
• Move to the other aircraft’s ELT antenna
• If the signal is stronger you probably have it; if weaker, its
probably the other aircraft
• May also put an aluminum foil ‘sleeve’ over the antenna
108
• Can also combine this with the signal-offset method
Which of these
planes is it in?
(Continued)

Use Little L-Per or…
• Use Body Shielding
• With any hand held aviation band radio, you can locate an ELT
• A Jetstream radio also works great
• Same concept as wing null method, you are just using your body to
block the signal to the antenna
• When you get very close, there will be too much signal to get a null
• Use Frequency Offset Method—try 121.6 instead of 121.5
• As you home in, tune in 121.6—you can tune further away the
closer you get
How to Body Shield - The Null
SIGNAL

No
•
•
•
Signal To Your Receiver
The Sound Gets Softer!
The ELT Is Directly To Your Back
Throw your thumb over your shoulder to
point to the ELT
NULL!
ELT
Airmobile UDF
Team 101

Once you’ve narrowed the suspects down to one or two
aircraft (usually side-by-side), remove the radio’s antenna
and hold it next to one of the ELT antennas

Turn the volume down until you just hear the signal

Don’t key the radio’s transmitter with the antenna removed

Move to the other aircraft’s ELT antenna

If the signal is stronger you probably have it; if weaker, its
probably the other aircraft

May also put an aluminum foil ‘sleeve’ over the antenna

Can also combine this with the frequency-offset method
Where is the thing?

ELTs are usually located in or near the rear of the aircraft. Also look for
remote switches.
• Single-engine Cessna: right side of the upper baggage area
immediately aft of the baggage door
• Multi-engine Cessna: left side of the fuselage just forward of the
horizontal stabilizer. Accessed through a small push-plate on the side
of the fuselage.
• Single- and multi-engine Piper: in the aft fuselage. Accessed through a
small access plate on the right side of the fuselage.
• Single- and multi-engine Bonanza: in the aft fuselage. Accessed
through a small access plate on the right side of the fuselage.
• Large piston twins (e.g., King Air) and small jets: if installed its
probably in the rear section. No visible antenna. May have a small
round push-plate that lets you manipulate the ELT switch.
112
Silencing the ELT


The preferred method is to have the owner (or someone
designated by the owner) turn it off and disconnect the
battery
Second best is to just turn it off
• The owner may take the switch to ‘Off’ and then back to
‘Armed’
• If this is done, stick around and monitor 121.5 to ensure it
doesn’t go off again

113
If you can’t find the owner, you may have to build a foil ‘tent’
(refer to CAPP-2)
Silencing the ELT
(Continued)





114
Foil Tent
1’ x 5’
Encloses antenna
Flaps at least 18”
beyond antenna
on fuselage
Securely taped
(masking tape
preferred)
Silencing the ELT
(Continued)


115
Ensure that the owner is notified that the ELT was disabled
If you can’t get a phone number, you can place a note on the
aircraft (not the window)
Legal Issues





116
Per CAPR 60-1 Chapter 1, CAP members will not enter private
property and should not do anything that could cause harm or
damage to the distress beacon or aircraft/boat
Entry to the ELT should be made by the owner or operator or
law enforcement
A transmitting ELT is under the legal authority of the FCC, and
federal law requires that it be deactivated ASAP (a crashed
aircraft is under the authority of the NTSB)
CAP members do not have the authority to trespass onto
private property, either to gain access to the aircraft or to
enter the aircraft to gain access to the ELT
Besides the owner/operator, some owners give FBO personnel
permission to enter their aircraft
Legal Issues
(Continued)


117
While entry upon private property may be justified if such an
act is for the purpose of saving life, every effort should be
made to obtain the controlling agency's and/or the property
owner's consent
If you need entry onto private property in order to search for
an ELT, law enforcement authorities such as local police, the
county sheriff's office or game wardens may be contacted for
assistance.
Legal Issues
(Continued)




118
Normally, local law enforcement officials are happy to assist
you; if they are not familiar with CAP and your
responsibilities, a simple explanation often suffices
If this doesn't work, try calling AFRCC and have them explain
the situation
The most important aspect is the manner in which you
approach the matter
The local civil authorities are in charge, if they tell you go
home, then phone the IC and/or AFRCC and close the mission
QUESTIONS?
ALWAYS THINK SAFETY!