Presentation on theme: "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."— Presentation transcript:
1 Authored by Rich Simerson 01-Jun-2007 Modified by Lt Colonel Fred Blundell TX-129 Fort Worth Senior Squadron For Local Training Rev Jan-2014
2 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.
3 Objectives Discuss the various types of ELTs. (O) Describe how an ELT can be detected. (O)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 fadeResponse when getting closeResponse as you pass over the beacon
4 Objectives (Continued) Describe the following ELT search methods: (O)HomingWing nullAuralSignalDiscuss signal reflection and interference. (O)Describe how to silence an ELT and the legal issues involved. (O)
5 Emergency Locator Transmitter Direction Finding for Aircrews Use Of Equipment Commonly Found In CAP AircraftN98987
6 Objective the Elusive ELT Automatic radio beacon (100 milliwatts)Roughly equal to that of a regular flashlightCan be heard on a line-of-sight basisRemember that the ELT may be attached to an aircraft or vessel in distress!
7 The ELT Activated by g-force (when armed) Some can be activated by the pilot in the cockpitThree frequencies:121.5 MHz (VHF emergency)243 MHz (UHF emergency – military guard)MHz (third generation advanced ELT/EPIRB/PLB)General types:General aviation aircraftMilitary (“beepers” or “beacons”)Marine EPIRBTest station (training practice beacon)Advanced (406)10.1.1Objective 10.1 – Discuss the various types of ELTs.
9 Most Aircraft Have ELTs Installed But they don’t always survive a crashLess than one-third of all crashes have a survivable (operable) ELT.
10 Most Aircraft Have ELTs Installed But they don’t always survive a crashLess than one-third of all crashes have a survivable (operable) ELT.
11 Military Beacons Most common type is the URT-33/C Personnel ejecting/parachuting will have a 243 MHz beaconSome downed pilots may be able to communicate via two-way radio on 243 MHz using a PRC-90 or later military survival radioBeacon mode transmits like an ELT on 243 MHzMost often, left locked in the aircraft. You search for the signal while the pilot is asleep in a local motel.Don’t be hesitant to call the Air Force; they take alarming beacons seriously and will send someone out to silence it.
12 Personal BeaconsPersonal Locator Beacon (PLB) or Personal Emergency Transmitter (PET):Intended for hikers and other remote wilderness travelersUse a 406 MHz transmitter and a MHz homing signal (at only 25 milliwatts)Many are also equipped with a built-in GPS receiver that provides lat/long coordinatesEach PLB must be registered[See discussion of Advanced ELTs]
13 Marine EPIRB Emergency Position Indicating Radio Beacon Similar to an ELT, an EPIRB is used on ships and boatsMandatory on certain commercial vesselsSome activate automatically and others are manually activatedContact the marina operator.
14 Advanced ELTs Designed to operate with SARSAT/COSPAS MHz beacons have data burst encoding that identifies each (registered) individual beaconAlso produces a MHz homing signal and may transmit GPS coordinatesSends 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)Still cost upwards of $1700, so don’t expect large-scale upgrades anytime soon.
15 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 MHz ELT)
16 Practice Beacon Training Practice Beacons Includes ones used by CAP All should be converted from to 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 radioMay cause confusionAlways use the term ‘Practice Beacon’Its called a “Practice Beacon,” not an ELT.
17 Testing an Aircraft ELT Can test the aircraft’s ELT within the first five minutes after each hourOnly allowed up to three sweepsWhen was the last time you tested the ELT in your aircraft?Do you regularly monitor MHz after you land?Ensure your ELT didn’t activateThis isn’t considered a test, by the way, but you can try this excuse if you like
18 Inadvertent Activation Excessively hard landings (Welcome aboard, Ensign!)Inadvertent change of switch positionDuring removal/installationMalfunctionNon-ELT source on MHz (computers, broadcast stations, even pizza ovens!)Monsieur MurphyCheck after landing. It’s very embarrassing to search for an ELT signal and find it in a CAP aircraft!
19 False AlarmsApproximately 97% of received ELT signals are false alarmsFor MHz ELTs abut 1 in 1000 are actual emergencies(2 in 100 composite alerts)For 406 MHz ELTs abut 1 in 10 are actual emergenciesWhat’s the big deal?SARSAT can only monitor 10 ELTs at onceEasy to overload the systemThey block emergency communications on and 243 MHz (guarded by towers, ARTCC, and the military)
22 Accuracy of SARSAT/COSPAS For a regular MHz beacon:Said to be a nautical mile radius (~ 452 square nm)Actually an oval shape with a 50% probability of being 15 nm wide and 7 nm highSystem is more accurate North to South (latitude)Average six-hour detection/alertFor a 406 MHz beacon it’s a 1-3 nm radius (~ 12.4 square nm) with 45 – 60 minute detection/alertFor a 406 MHz beacon with GPS it’s a 0.05 nm radius (within 100 yards) with an average five-minute detection/alert
23 So how should I treat an ELT Mission? AS AN EMERGENCY!Its not possible to know whether an ELT signal is a distress signal or a false alarmAlthough the statistics are against it, you must act as though it is a distress callIf you take advantage of them, every ELT mission allow you to keep your skills sharp!
24 Locating the ELT Signal Route or parallel track to pick up the signalIf no SARSAT hits or definitive LKP:4,000 to 10,000 AGLLarge track spacing (start at 60 nm, then do halves)Once signal is located, DF the signal10.2Objective 10.2 – Describe how an ELT can be detected.
25 Direction Finder (DF)A direction finder compares signal strengths from two antenna patterns to let the user know:When you are “centered” on a signalheaded directly towards OR away from the signal sourceWhich direction to turn when not centeredSimilar to an ADF needle, but only points left or right, hence the term “left-right homing”10.3.1Objective 10.3 – Describe how the aircraft DF works in both the Alarm and DF modes.
26 L - Tronics DF Normal: Alarm toggle in ‘up’ position DF: toggle is ‘down’
27 These are mounted on the bottom, but may be on top. DF AntennaThese are mounted on the bottom, but may be on top.
28 Step 1 Acquire the Signal To hear the signal you can use your L-Tronics receiver or one of your comm radiosTo 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 timeAllows for a weak or distant signal to be heardProceed at a reasonable altitude to the SARSAT composite hit, or to the point designated by your incident commander
29 Beginning the Search Altitude Selection Higher altitudes allow for reception of the ELT signal at greater distancesELTs transmit on MHz and MHz, both of which limit reception to “line of sight”Terrain will block ELT signalsHIGHER is therefore usually BETTER to acquire a signalMedium altitude is generally better for searching (after signal heard) - 3,000 to 5,000 AGLNO SIGNALSIGNALHEARD!ELT
32 Step 2 Track (DF) the Signal There are many different ways to DF an ELT signal:Left-Right DF Homing (L-Tronics DF)Wing Shadow MethodAural SearchMetered SearchCombinations of the above techniques10.4 – 10.7Objective 10.5 – Describe the following ELT search methods: homing, wing null (shadowing), aural search and signal search.
33 Wing ShadowingBy flying the airplane in a circle, at some point the wing will block the ELT signal to the receiver antennaThis causes an audible decrease in volume, called a “null”Almost any VHF-AM aircraft communications radio may be used with this method
34 Wing Shadowing Antennas To properly use the Wing Shadowing method, you MUST know where the antenna for the radio you are using is installed & located on the aircraftCommunications radio antennas are usually, but not always, located above the wingsCan be above the fuselage, in the tail, etc.L-Tronics Aircraft DF antennas may be above or below the aircraftBelow the aircraft is the preferred installation
37 How to DF by Wing Shadowing EW45135225315Fly a constant bank angle 360° turnthe audio will “null,”or get significantly quieter,when your wing blocks the antenna’s reception of the ELT signal10.5 – 10.7Objective 10.5 – D
38 Wing Shadowing-Signal Blocking For Antennas Above the Wings ELTNULLNULLNULL
39 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 LEFTSUBTRACT 90º from your headingNSEW45135225315ELT
40 Wing Shadowing-Signal Blocking For Antennas Below the Wings ELTNULL
41 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 headingNSEW45135225315ELT
42 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 signalBegin by plotting your position as soon as you receive the ELT signalFly that course for a short distance, then turn 90º left or right and proceed until the signal fadesTurn around (180º) and mark where the signal fades on the other side of the circlePlot chord lines similar to that of the diagramBisect the chord lines at a perpendicularPlot a course to the location where the perpendicular lines intersect: this should be the location of the target!
43 Aural Search commence low altitude pattern ELT SIGNAL FADES HEARD Equal signal strength circle:barely audible signal in aircraftreceiver at search altitudechord 1chord 2chord 3ELTcommence lowaltitude patterndescendingSIGNALFADESHEARD
44 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 OKNote your signal strength when beginning the searchFly a straight line until the signal gets lower, then increases to your original levelTurn 180º and return to the lowest level of signal, then turn 90º left or rightYou should now be headed directly towards or away from the transmitterIf the signal increases in strength, you are headed directly for the ELTIf the signal decreases in strength, turn 180º
46 Left-Right DF HomingMost CAP corporate aircraft have L-Tronics LA-Series Left-Right Homing DF unitsThese units operate virtually the same, but there are two major varieties:Single Meter ModelsDual Meter Models
47 L - Tronics DF Types VHF-DF VHF DF Single Meter Model Dual Meter Model ALARMOFFm SENS ®VOLVHF-DF243121.6AUX121.5DFRECL-TronicsALARMOFF243121.6AUX121.5m SENS ®VOLVHF DFDFSTRENGTH
48 Frequency Switch VHF-DF Selects frequency to be used Use MHz for actual ELTs/EPIRBs243.0 MHz may also be used for all actual electronic searchesUse MHz for trainingRefer to owners manual for use of the “AUX” positionL-TronicsALARMOFFm SENS ®VOLVHF-DF243121.6AUX121.5DFREC
49 Mode Switch VHF-DF Only Single-meter units have this switch Dual-meter units use two displays, so both REC and DF operate continuously and simultaneouslyREC is short for RECeive modeREC makes the unit’s dial work as a strength meterDF is short for Direction FindDF gives left-right homing to the ELT/EPIRB signalALARM is for NON-MISSION flights onlyUse only during normal flying to alert the presence of an ELT or EPIRBL-TronicsALARMOFFm SENS ®VOLVHF-DF243121.6AUX121.5DFREC
50 Volume & Sensitivity VHF DF Volume controls the audio level to the speaker or headsetsSensitivity controls the amount of signal that enters into the DF unitIt is critical that the proper amount of signal enters the DF: half-scale, or the middle, is an optimum starting placeAs the signal gets stronger, reduce SENSITIVITY, not volumeThe DF will be unreliable as too much signal is received, so you must cut out part of it by reducing the sensitivityMore than three-quarters scale is too muchL-TronicsALARMOFF243121.6AUX121.5m SENS ®VOLVHF DFDFSTRENGTH
51 DF Settings For Single Meter Models MISSIONSSelect (or for training missions)Select DF ModeTurn Sensitivity to Maximum (Full Clockwise)Turn Volume to About Mid-ScaleDF Needle Will Move Slightly Left and RightNON-MISSION FLIGHTSSelect 121.5Select Alarm ModeTurn Sensitivity To Maximum
52 DF Settings For Dual Meter Models MISSIONSSelect (or for training missions)Ensure Alarm Toggle OffTurn Sensitivity to Maximum (Full Clockwise)Turn Volume to About Mid-ScaleDF Should Stay About CenteredStrength Meter Will Move Up-Scale to RightNON-MISSION FLIGHTSSelect 121.5Turn Alarm Toggle OnTurn Sensitivity To Maximum
53 Pre-Flight Functional Check Just as you pre-flight the rest of the aircraft, you should preflight your DF when going on an ELT electronic search missionThese procedures are covered in the Mission Aircrew Reference Text.10.3.1, Normal Operations and Checks
54 Six StepsUse these 6 steps for locating ELTs and EPIRBs with L-Tronics LA- series airborne DF equipmentUse the full procedure every time for the best resultsRECeiveHALFDFTURNCHECKSHOOTEach of these steps will be described in detail in the slides to follow10.3.2Objective 10.4 – Discuss using the DF during a typical ELT search. Include how the DF should respond during the initial phase (including signal fade), when you are getting close, and when you pass over the beacon.
55 Step 1 - RECeiveOnce you have started to receive the ELT or EPIRB signal on the proper frequencyIf you have a single-meter unit, turn the mode selector to RECeive and turn the volume to a comfortable levelIf you have a dual meter unit, refer to the STRENGTH window (no need to change modes)
56 RECeive Mode/Strength Window In receive mode or in the strength window, the unit measures signal strengthNeedle to the left means low; to the right means highValues are relative depending on the sensitivity you have selectedYou may still be able to use the strength meter even if the DF is not functioning perfectlyIt is possible to locate an ELT using only the Receive ModeUtilize Aural Search/Metered Search methods to accomplishIf 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
57 Step 2: HalfNow that the unit is in RECeive mode and you have a good signal, turn the Sensitivity Knob to HALF SCALEThis is in the center of the windowIf you are flying with a dual-meter unit, turn the Sensitivity Knob so the needle reads HALF SCALE in the STRENGTH windowA half-scale strength reading will prevent too much signal (over sense) from entering the unit and will provide you with a good starting pointIt is also the optimum for the DF homing antennas
58 Step 3: DF 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)
59 A Direction Finding Primer Antenna Theory Antennas can be more or less directional depending on their designImagine a car radio antenna: it is unidirectionalIts pattern looks like the one on the leftA Satellite Dish is highly directionalIt would have a pattern like the one on the rightcar radioantenna(monopole)satellite dish (parabolic reflector)
60 DF Antenna Antenna Elements The aircraft DF unit has a 2 or 3 “element” antennaCommonly, we might call this two or three antennasIt just means there are two or three rods!This antenna setup is directionalOne element actually receives the signalThe other elements (rods) reflect the signal away from the first rodN98987Antenna Elements
61 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 hereThis pattern is called “carotid,” which means “heart-shaped”The pattern is the same even if the antennas are mounted above the wingElement 123
62 DF Unit Antenna Pattern REFLECTORELEMENTSTOP VIEWDIRECTIONALANTENNAPATTERNRECEIVINGELEMENTAIRCRAFT VIEW
63 Direction Finding Mode/Window The DF mode rapidly alternates the receiving and reflecting antenna elementsIt chooses one element as the receiver and the other two as the reflectors, then switches to the other setThis produces a carotid pattern each time the unit switchesone is shown in blue, the other in yellowBy comparing the two patterns, the unit will determine when they are equalWhen they’re equal, the needle centers!When the needle is centered, the target is either directly ahead or behind you!
64 Step 4: TurnTurn at least one FULL circle, noting where the DF needle centersUnder ideal conditions, the needle will center twiceWhen facing directly at the source of the signalWhen facing 180º away from the targetYou will solve this problem (called ambiguity) in the next step
65 When The Patterns Are Equal, The DF Needle Centers! DF CentersELT (Possibility 1)AlternatingAntennaPatternsWhen The Patterns Are Equal, The DF Needle Centers!AlternatingAntennaPatternsELT (Possibility 2)
66 Step 5: Check Use Turn to Tell Remembering that in DF mode the needle always points Direct to the Flipping targetWhen you have the needle centered, turn left or rightIf you turn left and the needle goes left, the ELT is 180º from your present headingIf you turn left and the needle turns right, the ELT is dead ahead
67 Ambiguity When Needle Centers ELT is Directly Ahead or Behind ELT (Possibility 1)When Needle CentersELT is Directly Ahead or BehindThis situation is called “ambiguity”To Solve ambiguity:Use Turn to TellMake a turn left or rightThe needle always points Direct to the Flipping Target (DF!)ELT (Possibility 2)
68 DF NeedleELTCompare the YELLOW (LEFT) and the BLUE (RIGHT) antenna patternsIn this case, the LEFT pattern is stronger than the RIGHTIn DF mode, the needle would then point LEFTThe needle always points Direct to the Flipping Target!
69 Solving Ambiguity Actual ELT position is unknown to user ELT (Possibility 1)ELT (Possibility 2)Solving AmbiguityActual ELT position is unknown to userMake a small turn left or rightAs a teaching reminder, “Use a TURN to TELL”
70 Solving Ambiguity Actual ELT position is unknown to user ELT (Possibility 1)ELT (Possibility 2)Solving AmbiguityActual ELT position is unknown to userMake a small turn left or rightAs a teaching reminder, “Use a TURN to TELL”Example:TURN LEFTneedle goes left
71 Solving Ambiguity Actual ELT position is unknown to user Make a small turn left or rightAs a teaching reminder, “Use a TURN to TELL”Example:TURN LEFTIf needle goes leftELT is to your left (behind you)ELT (Possibility 2)ELT (Possibility 2)
72 Solving Ambiguity If you turn Left and the needle moves Right ELT (Possibility 1)ELT (Possibility 2)Solving AmbiguityIf you turn Left and the needle moves RightThe ELT is in Front of you!
73 Solving Ambiguity If you turn Left and the needle moves Right ELT (Possibility 1)If you turn Left and the needle moves RightThe ELT is in Front of you!Example:Turn leftNeedle goes rightELT (Possibility 2)
74 Solving Ambiguity Solution: ELT (Possibility 1)Solution:If you turn Left and the needle moves RightThe ELT is in Front of you!
75 Step 6: ShootNSEW45135225315Use your DG to determine a bearing to the target & follow itYou may need to fly through a zone of signal dropoutBe watchful for signs of signal passageIf you get signal passage, consider using the “pinpointing the target” techniques listed in this presentationFrequently repeat the full six steps to ensure you are heading in the right direction and that you didn’t inadvertently over fly the ELT
76 How an L - Tronics DF Unit Works -Summary- Two Main Modes of OperationRECeiveDFRECeive Mode is a Strength MeterLeft is low, right is highDF Mode Centers on SignalAlways points to the signalUse a Turn to Tell when solving ambiguityAircraft and ground units work the same way
77 ReflectionsReflections of an ELT signal work just like a flashlight off of a mirrorAny flat, hard, or wet object can cause signal reflectionsMountains, especially cliff facesHangars and other metal structuresWet grass or snowLarge bodies of water or icePower lines can also have a large effect on a low-powered signal such as an ELT10.9Objective 10.6 – Discuss signal reflection and interference.
78 Beating Reflections Check your sensitivity at half-scale or lower But ensure that its high enough to receive adequate signalReflections will generally be weaker than the most direct path to the targetFollowing reflections will generally take your closer to the targetIf sensitivity is set to minimum, try DFing on a different frequencyFor example, if you are trying to locate an actual ELT on MHz, try locating it on or MHz when you get closeWhen all else fails, fly somewhere else to get a good DF bearing-or try that at the first sign of problems!
79 Beating ReflectionsYou don’t always need to hear the ELT or EPIRB to find itA carrier-only signal may be broadcasting with no audible sweepThis is especially true with low or old batteries, damaged ELTs, or spurious transmissionsYou can identify a carrier-only signal by DEFLECTIONIf it looks like you’re finding an ELT, even if you can’t hear it, you have good DEFLECTIONGood needle deflection generally indicates a signal that is strong enough to DF
80 Carrier-Only SignalsYou don’t always need to hear the ELT or EPIRB to find itA carrier-only signal may be broadcasting with no audible sweepThis is especially true with low or old batteries, damaged ELTs, or spurious transmissionsYou can identify a carrier-only signal by DEFLECTIONGood needle deflection generally indicates a signal that is strong enough to DF
81 Carrier-Only Signals Compare your deflection to another frequency If you are using MHz, try it on MHzIf deflection is the same in both frequencies, you DON’T have a signal, just random noiseIf deflection is different, keep at it! You have the signalIf 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.
82 Vertical Reflections and Signal Dropout The transmission pattern (similar to the reception pattern of the DF antennas, only for transmission) of an ELT is not a perfect circle or sphereIt has lobes, or, stronger and weaker pointsThis is accentuated when the ELT is transmitting from a location above the surrounding groundWhen you get a good DF heading and the signal fades or drops out completely you may just be outside of one of the signal lobesWhen you reacquire the signal, it should be stronger than when you lost it
83 Signal Dropout NO SIGNAL SIGNAL HEARD If you encounter a signal dropout, continue to fly on your last good DF headingYou should reacquire the signal in a few minutesActual time will depend upon your distance to the targetIf you are unable to reacquire, return to where you last heard the signal and re-DFNO SIGNALSIGNALHEARD
84 Signal StrengthThe rate of change in signal strength increases as you get closer to the transmitter, and RECeive mode or the STRENGTH window measures signal strengthThis 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) = 1/4After Scottish Physicist James Clerk Maxwell,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 signalThis should let you know that you’re getting close
85 Signal Strength Rate of Change m SENS ®VOL1234567
86 “Cone of Confusion” Cone of Confusion Antennas receive best when the pole is perpendicular to the signalWhen you approach the directly overhead position on an ELT, your DF will become unreliableIt may swing left and rightIt may center regardless of your headingYou should practice to see what this “station passage” reading looks likeIt is similar to crossing a VOR
87 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 tipsAlthough called a cone of silence, you will probably only see & hear a large decrease in signal instead of complete silenceantennasignalGOODPOOR
88 Pinpointing the ELTIf you get a station passage indication, make an approximate 180 degree turn and DF back to the targetRepeat 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 target123
89 Pinpointing the ELT After you think you have the target located make a low pass over the suspected location and visually scanif signal strength decreases significantly or drops out, climb back and try againthis is not the target: sometimes false targets will appear due to reflections or other interferenceIf you hear the ELT at low altitude, you probably have the right placea low pass down a runway might be a good idea if you suspect a particular airportDiscuss signal offset method as another way to pinpoint the signal.
90 Becker SAR-DF 517Completely different theory of operation from L-Tronics DFPseudo Doppler ShiftBeyond the scope of this courseThe advanced ELT course has an explanationEasy to useDisplays a delayed average heading to the beaconCan be used on 121.5, 243.0, or MHzAble to process newest ELTs, EPIRBs, & PLBs
92 PowerPOWER Press the ON/OFF button—unit should power up and illuminateBe prepared to execute the next steps…If you’re not fast enough, you may need to recycle power (turn it off and back on)
93 Mode MODE Using the PAGE knob (upper right knob), select: EMERGENCY for an actual SAR orTRAINING for a training missionThis setting can only be changed on power upRecycle power to change the ModeAfter setting EMERGENCY or TRAINING, just WAIT until the unit automatically goes to the next pageThe “wait time” is about 15 secondsDon’t push any buttons or turn any knobs during this period
94 Page Use the PAGE knob to cycle to desired page Page 1 is most like an ADFPage 2 is good for forward quarter onlyPage 3 is most easily read by the entire crew, but only in relative bearing
95 Tuning The lower-right +/- knob changes the frequency You want 121,500 for an actual SAR or 121,775 for trainingYou can alternately use 243,000 or 243,550 respectivelyYou will only be able to select training frequencies while in the training modeSimilarly, you can only select actual SAR frequencies in the emergency mode156,800 is for Marine Band Channel 16 EPIRBsNotice the commas: the Becker is made in Europe; the commas replace a decimal point
96 Squelch Setting Triangle Adjust the squelch knob on the upper left of the unitThe 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 barThe solid bar represents static or ambient noise, but you will want to listen and make sure that the “static” is not actually a signalWhen trying to acquire a signal, you may want the squelch all the way downYou may also want to do this to make sure you can hear audio from the BeckerTurn the lower left knob to adjust the volume to a comfortable listening levelSquelch KnobSquelch Setting TriangleAmbient Noise Level
97 Direction Finding (DF) Follow the relative bearings to the ELTUse homing procedures like an ADFCorrect for strong winds, if knownRemember 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 = TBRelative Bearing + True Heading = True BearingThis is also true if we replace magnetic bearing and heading instead of the trues: RB + MH = MBTherefore 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.
98 Becker Direction Finding Notes The clear marbles indicate when the Becker first and last receives the ELT signal in its circleWatching the clear marbles will give you an indication of how coherent your DF solution isThe marbles will always jump around; if they jump around a LOT you don’t have a good DFYou can test this by seeing what your indications are when you reduce the squelch enough to “DF” staticThe clear marbles will jump all over the placeStatic can sometimes look like a carrier-only signalThe dark marble should be fairly stable on an actual signal because of signal-averaging software>020>DARK MARBLECLEAR MARBLES
99 LocateAfter flying over the ELT, you should get a “station passage” indicationTurn around and re-DF to locate the targetThis is similar to locating with the L-Tronics DFIf you keep the signal at 090 or 270, you can fly a “turn around a point” using the DFIf the target isn’t visually significant, this will give your Scanner(s) the opportunity to put eyes on the target
100 Bearing on more than One Transmitter If bearing from a long distance, the DF will be pointing at the middle of the two transmittersThis is because the Becker averages the signals it getsExactly in the middle between two transmitters, the DF will display an unusable bearing valueThe clear marbles will swing WIDE (180 degrees or more) when in the middle of 2 averaged signalsExactly 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
101 Becker ThoughtsThe Becker unit is not as sensitive as the L-Tronics DF, so you must be significantly closer to the ELT to get initial signalBecause it uses averaging functions, it will not instantaneously point to an ELT like the L-Tronics unit—there is definitely a delayed reactionThe displays on the Becker lead you to believe that it is a pseudo-RMI 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 2Look to the “dark marble” to indicate the relative direction of the signal; this acts as an ADF-type pointer
102 Becker ThoughtsLook to the “dark marble” to indicate the relative direction of the signal; this acts as an ADF-type pointerIf 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 ELTBe 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
103 After Locating the ELTAfter location, coordinate with ground teams to bring them on-sceneUse radio communication and relay GPS coordinatesPick up the ground team at a predetermined location and lead them to the targetAlternately, coordinate a pick up point on the radioPractice your air-to-ground coordination skills oftentry it both with and without radio communicationAir-to-ground is CAP’s best unique ES skill!
104 DF Upon LandingMany 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 sceneYou can use a hand-held radio or hand-held DF unitThe most commonly used in CAP is the Little L-PerYou did remember to put one of these (with charged batteries) in the aircraft before you left, didn’t you?Practice with the Ground/Urban DF teams.
105 Little L - Per Six Steps Receive Half DF Center Turn Shoot The “Tracker” (made in Finland) is much easier to use and more accurate. More expensive, though. Advertises in CAP News.
106 Which of these planes is it in? You land at an airport with multiple hangars and each hangar is full of aircraftThis can make it difficult to find the ELTTwo methods can help:Signal-offsetUsing a hand-held radio without its antennaIf 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 significantlyDon’t forget to use your eyes. Some aircraft have remote indicating lights that flash (usually red) when the ELT is activated.Look for obvious signs that someone has been working near the ELT.Ask the FBO personnel if someone landed sometime before the first ELT report.
107 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 toAs you home in set in (you may even work up to 121.7)As you get further away from 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)
108 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 antennasTurn the volume down until you just hear the signalDon’t key the radio’s transmitter with the antenna removed!Move to the other aircraft’s ELT antennaIf the signal is stronger you probably have it; if weaker, its probably the other aircraftMay also put an aluminum foil ‘sleeve’ over the antennaCan also combine this with the signal-offset method
109 Which of these planes is it in? (Continued) Use Little L-Per or…Use Body ShieldingWith any hand held aviation band radio, you can locate an ELTA Jetstream radio also works greatSame concept as wing null method, you are just using your body to block the signal to the antennaWhen you get very close, there will be too much signal to get a nullUse Frequency Offset Method—try instead of 121.5As you home in, tune in 121.6—you can tune further away the closer you get
110 How to Body Shield - The Null SIGNALNo Signal To Your ReceiverThe Sound Gets Softer!The ELT Is Directly To Your BackThrow your thumb over your shoulder to point to the ELTELT
111 Airmobile UDF Team 101Once 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 antennasTurn the volume down until you just hear the signalDon’t key the radio’s transmitter with the antenna removedMove to the other aircraft’s ELT antennaIf the signal is stronger you probably have it; if weaker, its probably the other aircraftMay also put an aluminum foil ‘sleeve’ over the antennaCan also combine this with the frequency-offset method
112 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 doorMulti-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.Keep a record for future use.
113 Silencing the ELTThe preferred method is to have the owner (or someone designated by the owner) turn it off and disconnect the batterySecond best is to just turn it offThe owner may take the switch to ‘Off’ and then back to ‘Armed’If this is done, stick around and monitor to ensure it doesn’t go off againIf you can’t find the owner, you may have to build a foil ‘tent’ (refer to CAPP-2)10.10Objective 10.7 – Describe how to silence an ELT and the legal issues involved.
114 Silencing the ELT (Continued) Foil Tent1’ x 5’Encloses antennaFlaps at least 18” beyond antenna on fuselageSecurely taped (masking tape preferred)Be very careful not to damage the antenna or the paint (assume the owner won’t find it for awhile)
115 Silencing the ELT (Continued) Ensure that the owner is notified that the ELT was disabledIf you can’t get a phone number, you can place a note on the aircraft (not the window)Can make your own.
116 Legal IssuesPer 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/boatEntry to the ELT should be made by the owner or operator or law enforcementA 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 ELTBesides the owner/operator, some owners give FBO personnel permission to enter their aircraftDon’t let all this legal stuff intimidate you; its your job to find it and silence it.
117 Legal Issues (Continued) 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 consentIf 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.
118 Legal Issues (Continued) Normally, local law enforcement officials are happy to assist you; if they are not familiar with CAP and your responsibilities, a simple explanation often sufficesIf this doesn't work, try calling AFRCC and have them explain the situationThe most important aspect is the manner in which you approach the matterThe local civil authorities are in charge, if they tell you go home, then phone the IC and/or AFRCC and close the mission
119 QUESTIONS? ALWAYS THINK SAFETY! Be sure to submit paperwork for “Find” and “Save” awards (CAPF 2a) for yourself and your crew.
Your consent to our cookies if you continue to use this website.