Presentation on theme: "This course is designed to give a basic introduction to how electronic searches for downed aircraft are conducted. It includes use of the L-Tronics “Little."— Presentation transcript:
1This course is designed to give a basic introduction to how electronic searches for downed aircraft are conducted. It includes use of the L-Tronics “Little L-Per™,” triangulation, body shielding, and activation of CAP. This course is mainly focused on the ground team member aspect of electronic search.Authored by Scott E. Lanis 28-Aug-1998Modified by Lt Colonel Fred BlundellTX-129 Fort Worth Senior SquadronFor Local Training Rev Feb-2014
2OBJECTIVES By the end of this course, you should: Know what an ELT is, and how it can be activatedUnderstand why an ELT signal is an emergencyDescribe how CAP is called out on an electronic searchBe familiar with these fundamentals:Plotting a SARSAT hit on a map (latitude/longitude)Direction finding - Little L-Per™ OperationTriangulationBody shieldingAircraft coordination/LORAN/GPS operationsGround Vehicle Operations
3Is an Aircraft Missing? How would we know? Radio distress call Monitored aircraft drops from RADAROverdue Flight PlanReport from friends/relativesELT Signal (maybe!)
4How does CAP Search for Missing Aircraft? Purely Visual SearchesVery Difficult: often few cluesAir - most effective to cover groundGroundElectronic Searches - “Quick” (24 hrs)Air - best reception and rangeGround - autonomous search is slower and more difficultAdvanced TechnologyFew of these resources available directly to CAPSynthetic Aperture Radar (SAR), Thermal/Infrared Imagery, Other Remote Sensing (satellites/reconnaissance aircraft)A purely visual search is often a nearly impossible task when the range and speed of a missing aircraft is considered.An airborne search covers the most ground per period of time.Ground searches by themselves are ineffective. (not including ramp and bastard searches)This “cutting edge” technology was heavily utilized in Colorado’s search for Craig Buttons’ A-10.
5What Will A Crashed Airplane Look Like? Your second most likely place to find a Bonanza. JOKE! I love Bonanzas.An aircraft like this is likely to have survivors-and they’ve likely already gone home and left the ELT operating! (I’ve seen this twice)
6Air to Ground Coordination The most effective way to searchThe only way CAP stays in the SAR businessThe plan:CAP aircraft locates crash (visual / electronic)Coordinates to bring ground team on sceneRadio (transmit the Lat-Longs from LORAN/GPS!)Radio OutLat-Long (LORAN/GPS)Ground Team effects rescue
7Aircraft LimitationsWeatherCan’t pinpoint signalRow of hangers
8Ground Search Types for Missing Aircraft Ramp SearchEnsure the missing aircraft has not landed safelyCan be conducted by both air and ground crewsBastard SearchEnsure the missing person isn’t in a favorite hangout“You bastard!”
9How does a search start?There is the possibility of a missing aircraftRadio distress call, aircraft drops from RADAR, overdue flight plan, report from friends/relatives, ELT SignalAFRCC performs a telephone searchAirport managers, towers, etc.Missing Aircraft Confirmed!AFRCC activates the appropriate CAP wingAFRCC will try to resolve the ELTAFRCC will call airport managers to see if they receive a signal that seems to be near an airfieldif a signal is received on the field, the manager will responsibly disable the ELTIf no airports are in the vicinity, a CAP search is initiated after a set period of time has passedIf the signal coincides with an overdue aircraft or unclosed flight plan, search begins fasterCAP often is called out “after hours” when there are no airport managers left at work!CAP answers the call because everyone else has gone home.
10What if only an ELT signal is received? AFRCC Telephone SearchAirports: “Do you hear it too?”Likely false alarm at this point; signal silenced by crews on airportCAP called sooner if “after hours”No one else answers the phone!Is there another indicator of a missing aircraft?If not, AFRCC will wait to see if the signal terminatesTestsInadvertent actuations terminated
11What is an ELT anyway? Emergency Locator Transmitter It’s an automatic radio beacon!3 Frequencies of Operation121.5 MHz (VHF)AND 243 MHz (UHF) (Military Guard)MHz (new)Most aircraft have ELTs installed
12General Types of ELTs Aircraft (General Aviation) Military (“beepers” or “beacons”)Personal (PELTs or PLBs)Marine EPIRBsAdvanced (406/GPS)
13Typical Aircraft ELT Operation 3 Switch positions--on, arm/standby, and offG-switch activated (Generally 9G)Activates ELT upon impact when armedMay be manually operated by placing the switch in in the ‘ON’ position
14Can you test an ELT? Yes, with restrictions: First 5 minutes of the hour, no more than 3 sweepsBattery must be replaced after:One cumulative hour of use or50% of useful life has expiredFAR §91.207(c)Does not apply to our Practice BeaconsCall nearest FSS in advance: 1 (800) WX-BRIEFGive a contact phone-interference happens on !
15Inadvertent Activation of an ELT May Occur From Excessively hard landingInadvertent change of switch positionRemoval of the unitactivating the switch or G-switchMalfunctionswitch shortbattery leakage
16Who is listening? SARSAT/COSPAS FAA Facilities FSS, Centers, Towers AirlinersOnly if pilot choosesMilitary Aircraft243 MHz RequiredGeneral Aviation AircraftThat’s us! Help the system work: monitor MHzSignal report is relayed to AFRCC
18How SARSAT Works Receive 121.5, 243, 406 MHz Signals Orbiting and Geostationary SatellitesOrbiting: SARSAT/COSPASHigh Inclination (polar) orbitsGeostationary: GOES Weather SatellitesSAR payloads for 406 onlyOperated by Canada, France, Russia, USAThey give us digital lat-long coordinatesCAP Mission Coordinator plots these and assigns assetsGround teams must interpret for land navigation
19System Operation Details SARSAT/COSPAS in polar orbitCalculates location of signal by measuring Doppler shiftThis yields a latitude and a distance
20Narrowing the Search (SARSAT/COSPAS Only) First passAmbiguity
21Where Is It? Second Pass average 30-45 minute wait Ambiguity resolved 5-12 Nautical Mile Average Error
22How do Different ELTs stack up? 121.5 MHz ELT12 NM Radius, 452 Sq MiAve. 6 Hour Notification60 Milliwatt Transmitter406 MHz ELT2 NM Radius, 12.5 Sq MiAve. 1 Hour Notification25 Milliwatt Beacon406 ELT with GPS.05 NM Radius, .008 Sq MiAve. 5 minute NotificationDiagram and information adapted from NOAA Pamphlet, with the exception of 25 milliwatt beacon.Note that hunting ELTs by signal alone will become much more difficult with less than 1/2 the power (inverse square law says less than 1/4 the effective radius from previous ELTs) but hopefully uncommonFood for thought: how common will the GPS portion of an ELT fail with the beacon operating?? That’s anyone’s guess.
23System Review ELT, PLB, EPIRB Signal Received AFRCC gets coordinates from SARSATAppropriate CAP Wing is activated
24False Alarms 97% of received ELTs are false alarms 121.5 MHz: 1 in 1000 is an actual emergency (0.1%)406 MHz: 1 in 8 is an actual emergency (12.5%)Why is a False Alarm a big deal?SARSAT can only monitor 10 ELTs at once (within footprint)bent-pipe repeaterVERY easy to overload the systemBlocks emergency communicationsBlocks the real emergency!
25How should we treat an ELT? As an EMERGENCY!You can’t know which ones are Distress ELTsAnd even the false ones are good training!
26Transportation to Target Ground Teams generally will use vehicles for transportation to and from mission baseAircraft Coordination will get the Ground Team to the target the fastestIf no aircraft is available:Vehicles provide enough speed and range to triangulateClose range may be required for signal acquisition
27Direction Finding DF unit Measures equal strengths of signal not wholly accurate, but good enough!Therefore, when needle is centered, ELT could be either directionNeedle always POINTS to the ELT (DF=Direct to the Flipping target)Use a TURN to TELL if the ELT is in front or behind you
28DFing with the Little L-Per 6 Steps: use the full procedure every time!Turn the unit to Receive, check proper frequency and volumeTurn the Sensitivity Knob to HALF SCALEThis will prevent oversense and a good starting pointTurn the unit to DF (Direct to the Flipping target)Turn at least one FULL circle, stopping and calling, “Center!”Check: Use Turn to Tell: the needle will point Direct to the Flipping targetUse your compass, shoot an azimuth to get a bearing to the ELT
31Little L-Per Receive Mode Measures Signal Strength onlyFrom a direction of the arrows on the antenna (to your left)Use it with multiple centers (more than 2) to verify strongest pathDue ReflectionsThat’s most likely the true direction to the ELT
32Reflections Caused by flat surfaces Hangars are notorious Rock wall, cliff, or mountainsTo beat reflectionsCheck sensitivity half scale oftenUse RECeive modeRubber ducky antennaOff-frequency tuningUsually strongest DF center is not a reflection
33TriangulationBest method for ground troops to get an accurate fix when search aircraft support is unavailableYou must be able to receive the signalCenter up DF unit on the signalTake the magnetic bearing (shoot an azimuth)Correct for magnetic variationEast is least, West is bestPlot your bearings (draw a line) on mapThe ELT should be where the lines cross!
35Body Shielding The BEST method of beating reflections at close range Can use L-Per™Radio Shack JETSTREAM radio is better and CHEAP!At extremely close range, a 2m VHF radio unsquelched may workThis works ok when trying to figure out a particular aircraft on a flight line, it will probably not identify a particular hangarBody blocks out the signalCalled a NULLNull should be at your BACK
36Off-Frequency Tuning Decrease sensitivity when: Sensitivity (L-Per™) is at the minimum and signal is still too strong (full scale on receive)You don’t get a null during body shieldingYou don’t have a sensitivity knob (Jetstream)Shortening (Jetstream) or removing (Little L-Per™) the antenna will also decrease sensitivityOff-Frequency tuning may be used any time you have too much signal, but this technique is especially effective during body shielding
37I can’t hear the signal! ELTs are limited to Line of Sight propagation You don’t always need to hear the ELTCarrier wave may be broadcasting with no audible sweepEspecially true in low batteries, or odd transmissionsYou can tell by DEFLECTIONGood needle deflection generally indicates a signal that is strong enough to DF
38What else can affect an ELT signal? Power linesEM RadiationIf you get an actual ELT during a practice search, shut down all practice beacons. The signal on may be frequency shifted from your practice beacon! (often due to power lines)Fence Line (signal can follow)Coffee Can/Stovepipe effectHangarsMoving Target
39How does an aircraft perform an electronic search? Aircraft use the same type of methods as used on the groundDF mode (most common)Wing Null Method (body shielding with the wing!)Signal StrengthAural Search (rare)
40Before going home, silence the signal! Sometimes that’s the only goal!Methods of disabling an ELT:Switch off (not always effective!)Foil tentGrounding wireRemove batteryRemove antennaThe Sheriff is required for forcible entryMost folks will be very cooperativeEnsure the aircraft operator is notified you disabled the ELT!
41Summary You Should Now: Know what an ELT is and how it can be activatedUnderstand why an ELT signal is an emergencyDescribe how CAP is called out on an electronic searchBe familiar with these fundamentals:Plotting a SARSAT hit on a map (latitude/longitude)Direction finding - Little L-Per™ OperationTriangulationBody shieldingAircraft coordination/LORAN/GPS operationsGround Vehicle Operations