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Authored by Scott E. Lanis 28-Aug-1998 Modified by Lt Colonel Fred Blundell TX-129 Fort Worth Senior Squadron For Local Training Rev 5.0 02-Feb-2014. OBJECTIVES. By the end of this course, you should: Know what an ELT is, and how it can be activated

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slide1

Authored by Scott E. Lanis 28-Aug-1998

Modified by Lt Colonel Fred Blundell

TX-129 Fort Worth Senior Squadron

For Local Training Rev 5.0 02-Feb-2014

objectives
OBJECTIVES
  • By the end of this course, you should:
      • Know what an ELT is, and how it can be activated
      • Understand why an ELT signal is an emergency
      • Describe how CAP is called out on an electronic search
      • Be familiar with these fundamentals:
        • Plotting a SARSAT hit on a map (latitude/longitude)
        • Direction finding - Little L-Per™ Operation
        • Triangulation
        • Body shielding
        • Aircraft coordination/LORAN/GPS operations
        • Ground Vehicle Operations
is an aircraft missing
Is an Aircraft Missing?
  • How would we know?
    • Radio distress call
    • Monitored aircraft drops from RADAR
    • Overdue Flight Plan
    • Report from friends/relatives
    • ELT Signal (maybe!)
how does cap search for missing aircraft
How does CAP Searchfor Missing Aircraft?
  • Purely Visual Searches
    • Very Difficult: often few clues
      • Air - most effective to cover ground
      • Ground
  • Electronic Searches - “Quick” (24 hrs)
      • Air - best reception and range
      • Ground - autonomous search is slower and more difficult
  • Advanced Technology
    • Few of these resources available directly to CAP
      • Synthetic Aperture Radar (SAR), Thermal/Infrared Imagery, Other Remote Sensing (satellites/reconnaissance aircraft)
air to ground coordination
Air to GroundCoordination
  • The most effective way to search
  • The only way CAP stays in the SAR business
  • The plan:
    • CAP aircraft locates crash (visual / electronic)
    • Coordinates to bring ground team on scene
        • Radio (transmit the Lat-Longs from LORAN/GPS!)
        • Radio Out
        • Lat-Long (LORAN/GPS)
    • Ground Team effects rescue
aircraft limitations
Aircraft Limitations
  • Weather
  • Can’t pinpoint signal
    • Row of hangers
ground search types for missing aircraft
Ground Search Types for Missing Aircraft
  • Ramp Search
    • Ensure the missing aircraft has not landed safely
    • Can be conducted by both air and ground crews
  • Bastard Search
    • Ensure the missing person isn’t in a favorite hangout
    • “You bastard!”
how does a search start
How does a search start?
  • There is the possibility of a missing aircraft
      • Radio distress call, aircraft drops from RADAR, overdue flight plan, report from friends/relatives, ELT Signal
  • AFRCC performs a telephone search
      • Airport managers, towers, etc.
  • Missing Aircraft Confirmed!
      • AFRCC activates the appropriate CAP wing
what if only an elt signal is received
What if only an ELTsignal is received?
  • AFRCC Telephone Search
    • Airports: “Do you hear it too?”
      • Likely false alarm at this point; signal silenced by crews on airport
    • CAP 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 terminates
      • Tests
      • Inadvertent actuations terminated
what is an elt anyway
What is an ELT anyway?
  • Emergency Locator Transmitter
    • It’s an automatic radio beacon!
  • 3 Frequencies of Operation
    • 121.5 MHz (VHF)
    • AND 243 MHz (UHF)(Military Guard)
    • 406.025 MHz (new)
  • Most aircraft have ELTsinstalled
general types of elts
General Types of ELTs
  • Aircraft (General Aviation)
  • Military (“beepers” or “beacons”)
  • Personal (PELTs or PLBs)
  • Marine EPIRBs
  • Advanced (406/GPS)
typical aircraft elt operation
Typical Aircraft ELTOperation
  • 3 Switch positions--on, arm/standby, and off
  • G-switch activated (Generally 9G)
  • Activates ELT upon impact when armed
  • May be manually operated by placing the switch in in the ‘ON’ position
can you test an elt
Can you test an ELT?
  • Yes, with restrictions:
    • First 5 minutes of the hour, no more than 3 sweeps
  • Battery must be replaced after:
    • One cumulative hour of use or
    • 50% of useful life has expired
    • FAR §91.207(c)
  • Does not apply to our Practice Beacons
    • Call nearest FSS in advance: 1 (800) WX-BRIEF
    • Give a contact phone-interference happens on 121.775!
inadvertent activation of an elt may occur from
Inadvertent Activationof an ELT MayOccur From
  • Excessively hard landing
  • Inadvertent change of switch position
  • Removal of the unit
    • activating the switch or G-switch
  • Malfunction
    • switch short
    • battery leakage
who is listening
Who is listening?
  • SARSAT/COSPAS
  • FAA Facilities
    • FSS, Centers, Towers
  • Airliners
    • Only if pilot chooses
  • Military Aircraft
    • 243 MHz Required
  • General Aviation Aircraft
    • That’s us! Help the system work: monitor 121.5 MHz
  • Signal report is relayed to AFRCC
how sarsat works
How SARSAT Works
  • Receive 121.5, 243, 406 MHz Signals
  • Orbiting and Geostationary Satellites
    • Orbiting: SARSAT/COSPAS
      • High Inclination (polar) orbits
    • Geostationary: GOES Weather Satellites
      • SAR payloads for 406 only
  • Operated by Canada, France, Russia, USA
  • They give us digital lat-long coordinates
    • CAP Mission Coordinator plots these and assigns assets
    • Ground teams must interpret for land navigation
system operation details
System OperationDetails
  • SARSAT/COSPAS in polar orbit
  • Calculates location of signal by measuring Doppler shift
  • This yields a latitude and a distance
where is it
Where Is It?
  • Second Pass
      • average 30-45 minute wait
      • Ambiguity resolved
      • 5-12 Nautical Mile Average Error
how do different elts stack u p
How do Different ELTs stack up?
  • 121.5 MHz ELT
    • 12 NM Radius, 452 Sq Mi
    • Ave. 6 Hour Notification
    • 60 Milliwatt Transmitter
  • 406 MHz ELT
    • 2 NM Radius, 12.5 Sq Mi
    • Ave. 1 Hour Notification
    • 25 Milliwatt 121.5 Beacon
  • 406 ELT with GPS
    • .05 NM Radius, .008 Sq Mi
    • Ave. 5 minute Notification
    • 25 Milliwatt 121.5 Beacon
system review
System Review
  • ELT, PLB, EPIRB Signal Received
  • AFRCC gets coordinates from SARSAT
  • Appropriate CAP Wing is activated
false alarms
False 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 repeater
    • VERY easy to overload the system
    • Blocks emergency communications
  • Blocks the real emergency!
how should we treat a n elt
How should wetreat an ELT?
  • As an EMERGENCY!
    • You can’t know which ones are Distress ELTs
  • And even the false ones are good training!
transportation to target
Transportation to Target
  • Ground Teams generally will use vehicles for transportation to and from mission base
  • Aircraft Coordination will get the Ground Team to the target the fastest
  • If no aircraft is available:
    • Vehicles provide enough speed and range to triangulate
    • Close range may be required for signal acquisition
direction finding
Direction Finding
  • DF unit Measures equal strengths of signal
      • not wholly accurate, but good enough!
  • Therefore, when needle is centered, ELT could be either direction
  • Needle 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
dfing with the little l per
DFing with theLittle L-Per
  • 6 Steps: use the full procedure every time!
      • Turn the unit to Receive, check proper frequency and volume
      • Turn the Sensitivity Knob to HALF SCALE
        • This will prevent oversense and a good starting point
      • Turn 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 target
      • Use your compass, shoot an azimuth to get a bearing to the ELT
slide30
REC
  • 1/2
  • DF
  • Center
  • Turn
  • Shoot
little l per receive mode
Little L-Per Receive Mode
  • Measures Signal Strength only
    • From a direction of the arrows on the antenna (to your left)
  • Use it with multiple centers (more than 2) to verify strongest path
    • Due Reflections
    • That’s most likely thetrue direction to the ELT
reflections
Reflections
  • Caused by flat surfaces
    • Hangars are notorious
    • Rock wall, cliff, or mountains
  • To beat reflections
    • Check sensitivity half scale often
    • Use RECeive mode
    • Rubber ducky antenna
    • Off-frequency tuning
    • Usually strongest DF center is not a reflection
triangulation
Triangulation
  • Best method for ground troops to get an accurate fix when search aircraft support is unavailable
  • You must be able to receive the signal
      • Center up DF unit on the signal
      • Take the magnetic bearing (shoot an azimuth)
      • Correct for magnetic variation
        • East is least, West is best
      • Plot your bearings (draw a line) on map
      • The ELT should be where the lines cross!
body shielding the best method of beating reflections at close range
Body 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 work
      • This works ok when trying to figure out a particular aircraft on a flight line, it willprobably not identify a particular hangar
  • Body blocks out the signal
    • Called a NULL
    • Null should be at your BACK
off frequency tuning
Off-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 shielding
      • You don’t have a sensitivity knob (Jetstream)
      • Shortening (Jetstream) or removing (Little L-Per™) the antenna will also decrease sensitivity
  • Off-Frequency tuning may be used any time you have too much signal, but this technique is especially effective during body shielding
i can t h ear the signal
I can’t hear the signal!
  • ELTs are limited to Line of Sight propagation
  • You don’t always need to hear the ELT
    • Carrier wave may be broadcasting with no audible sweep
  • Especially true in low batteries, or odd transmissions
  • You can tell by DEFLECTION
  • Good needle deflection generally indicates a signal that is strong enough to DF
what else c an a ffect a n elt signal
What else can affect an ELT signal?
  • Power lines
    • EM Radiation
    • If you get an actual ELT during a practice search, shut down all practice beacons. The signal on 121.5 may be frequency shifted from your practice beacon! (often due to power lines)
  • Fence Line (signal can follow)
  • Coffee Can/Stovepipe effect
  • Hangars
  • Moving Target
how does a n a ircraft p erform a n e lectronic s earch
How does an aircraft perform an electronic search?
  • Aircraft use the same type of methods as used on the ground
      • DF mode (most common)
      • Wing Null Method (body shielding with the wing!)
      • Signal Strength
      • Aural Search (rare)
before going home silence t he s ignal
Before going home,silence the signal!
  • Sometimes that’s the only goal!
  • Methods of disabling an ELT:
    • Switch off (not always effective!)
    • Foil tent
    • Grounding wire
    • Remove battery
    • Remove antenna
    • The Sheriff is required for forcible entry
      • Most folks will be very cooperative
  • Ensure the aircraft operator is notified you disabled the ELT!
summary
Summary
  • You Should Now:
      • Know what an ELT is and how it can be activated
      • Understand why an ELT signal is an emergency
      • Describe how CAP is called out on an electronic search
      • Be familiar with these fundamentals:
        • Plotting a SARSAT hit on a map (latitude/longitude)
        • Direction finding - Little L-Per™ Operation
        • Triangulation
        • Body shielding
        • Aircraft coordination/LORAN/GPS operations
        • Ground Vehicle Operations
questions

QUESTIONS?

Always Think Safety!