# Presentation: 450411

## ELT DF Training 

*BASIC & URBAN GROUND ELT LOCATION COURSE*

## Credits

- Developed By
- Major David A. Rudawitz Oregon Wing CAP, rudawitzd@acm.org
- Adapted from
-  “ELTs: Everything You Wanted to know-and More - Basic Ground ELT Location Course (Classroom)” - Scott E. Lanis of Vermont Wing CAP
- “Ground ELT / DF Training” - Richard DeCastro California Wing CAP
- Copyrighted material from both sources included in this training program

## Schedule

- Basic ELT/DF Training
- Urban ELT/DF issues
- Classroom and field training in both sessions

## Basic ELT/DF Training

**Classroom Session**

## 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
- Be familiar with these fundamentals:
- Basics of the SARSAT system
- Direction finding - Little L-PerTM Operation
- Triangulation
- Body shielding
- Practice and experience to become Expert

## 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!)

## Search for Missing Aircraft

- Purely Visual Searches
- Very Difficult: often few clues
- Air - most effective to cover ground
- Ground - very limited visual range
- Electronic Searches - “Quick” (24 hrs)
- Air - best reception and range
- Ground - autonomous search is slower and more difficult
- Advanced Technology
- Synthetic Aperture Radar (SAR), Thermal/Infrared Imagery, Other Remote Sensing (satellites/reconnaissance aircraft)

## What Will A Crashed Airplane Look Like?

## Aircraft Limitations

- Weather
- Ground terrain
- Trees
- Shadows
- Can’t pinpoint signal
- Row of hangers/planes
- Buildings
- Marina full of boats

## What is an ELT?

- 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 ELTs installed

##  General Types of ELTs

- Aircraft (General Aviation)
- Military (“beepers” or “beacons”)
- Personal (PELTs or PLBs)
- Marine EPIRBs
- Advanced(406/GPS)

## What are EPIRB’s

- EPIRB - Emergency Position Indicating Radio Beacon
- For boats and ships
- Some designed to float, some water activated
- Sounds JUST LIKE an ELT

## Typical Aircraft ELT Operation

- 3 Switch positions (usually)
- on
- arm/standby
- 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

## Inadvertent Activation of an ELT 

**May Occur From**:
- Excessively hard landing
- Ground incident like high winds
- Inadvertent change of switch position
- Removal of the unit
- activating the manual switch or G-switch
- Malfunction
- switch short
- battery leakage

## Who is listening?

- SARSAT/COSPAS
- FAA Facilities - FSS, Centers, Towers
- Airliners - Only if pilot chooses
- Military Aircraft
- 243 MHz Required
- General Aviation Aircraft
- Some ham radio operators
- Signal report is relayed to AFRCC

## SARSAT/COSPAS

## 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

## System Operation Details

- SARSAT/COSPAS in polar orbit
- Calculates location of signal by measuring Doppler shift
- This yields a latitude and a distance

## Narrowing The Search (SARSAT/COSPAS Only)

- First pass
- Ambiguity

## Where Is It?

- Second Pass
- average 30-45 minute wait
- Ambiguity resolved
- 5-12 Nautical Mile Average Error

## 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

## False Alarms

- 97% of received ELTs are false alarms
- 121.5 MHz: 1 in 1000 is an actual emergency
- 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)
- VERY easy to overload the system
- Blocks emergency communications
- Blocks a real emergency!

## How Should We Treat An ELT?

- As an ***EMERGENCY***!
- You can’t know which ones are distress ELTs
- And even the false ones are good training!

*Search is an Emergency*
- National Association of Search and Rescue

## 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
- Use a TURN to TELL if the ELT is in front or behind you

## DFing with theLittle L-PerTM

- 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
- Turn at least one FULL circle
- Check: Use **T**urn to **T**ell: the needle will point Direct to the target
- Use your compass, to get a bearing to the ELT

## Turn to Tell Direction

## Procedure

- REC
- 1/2
- DF
- Center
- Turn
- Shoot

## Little L-PerTM 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 to Reflections
- That’s most likely thetrue direction to the ELT

## Taking Bearings

- Make sure that nothing magnetic is in the way
- Always use MAGNETIC Bearings - but be careful when plotting
- Can be used to plot bearings to triangulate the location

## Monitoring while Driving

- Drive first
- Take bearings second
- Pull over and park in safe location
- Park off pavement whenever possible
- Use rotating/strobe beacons on vehicle
- Where bright reflective outerwear for high visibility

## General Tips and Hints

- Always have communications with the IC
- Radio or cellphone and phone numbers
- Maps
- Be in some kind of _approved_ uniform
- Golf Shirt, Orange ground team shirt, Jump suit, blues -  NOT BDU’s in urban area
- Appropriate outerwear and footgear for weather

## 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

- Best method for ground personnel to get an accurate fix when search aircraft support is unavailable

## Triangulation

- 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!

## Let’s See That

## Hey, 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 deflectiongenerally indicates asignal that is strongenough to DF

## 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 powerlines)
- Fence Line (signal can follow)
- Coffee Can/Stovepipe effect
- Hangars
- Moving Target

## Selective shielding

- Objects near the signal source will selectively shield the signal
- Resulting radiation pattern will be:
- non-uniform
- erratic
- deceptive

- No Signal

- No Signal

- No Signal

## 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)

## Finding it (Finally)

- Notify IC - note time of first acquiring signal, location and silence
- Determine Location (lat/long) and address
- Access available?
- Law enforcement assistance needed?
- Residence or business
- No trespassing
- No access
- Ensure the aircraft operator is notified you disabled the ELT!

## Before Going Home, Silence The Signal!

- Sometimes that’s the only goal!
- Methods of disabling an ELT:
- Switch off (note position!)
- Foil tent or tube
- Grounding wire
- Remove battery
- Remove antenna

## Leave A Note:

- Mission Number and RCC phone Number
- NOTICE:  YOUR ELT or EPIRB HAS BEEN Transmitting a distress signal.  It has been secured by Civil Air Patrol
- The batteries MUST BE REPLACED!
- Contact RCC for more information
- Personal information is optional

## Data to Record

- Make, model, S/N of ELT
- Date of batteries
- Location
- Make, model and tail number if on aircraft
- Times - 1st heard signal, located ELT and silenced

## QUESTIONS?

## Slide 45

## Urban ELT/DF Training

**Classroom Session**

## OBJECTIVES

- By the end of this session, you should:
- Understand basic urban ELT/DF search issues
- Be familiar with these fundamentals:
- Close in DF techniques
- Body shielding

## Why is Urban ELT/DF Different

- Usually not a crashed aircraft as signal source
- Massive amounts of interference
- Computers
- EMF - power lines, lights ...
- Significant reflections
- Buildings, boats, steel ...

## Why is Urban ELT/DF Different 

- Visual clues not available
- Too many target possibilities (flightline, marina, etc.)
- Signal range may be limited
- Signal quality may be poor (carrier only)

## Where Might the ELT Be?

- Usual suspects - planes, boats, pilot’s/boat owner’s house
- Marine/Aviation supply stores
- Avionics/radio repair facilities
- Pawn shops
- Junk yards, storage yards
- Trains, trucks and other transport

## Location Process

- Process any available data - SARSAT, PIREPS
- Use a high point to DF down over potential area
- Triangulate if possible
- Close in with “spiral pursuit”
- Close-in techniques
- “Throw out your ELT and come out with your hands up”

## Process any available data

- Plot hits on the map
- Plot/interpret data from aircraft
- Solicit additional PIREPS (helicopters (media, PD, etc.))
- Look for potential source locations (marinas, avionics shops, etc.)

## Use a High Point to DF Down Over Potential Area

- Top of hill, bridge, etc. - try to get an overview position
- Try to acquire signal
- If yes - get a bearing
- Try to triangulate from other locations

## Acquire Signal

- You must acquire the signal in order to DF the target!
- If you can not acquire signal, *mission over*

## Close in with “spiral pursuit”

- Follow signal into source
- Spiral into source by driving, stopping, DFing

## End of the Line - Now What

- Unless the source is obvious, close-in techniques will be needed to actually find the source
- Look for clues to help
- Signs of a pilot or boat owner in the house
- Light on EPIRB is on
- Use all your senses - it is not cheating

## Close-in Techniques

- Turn down sensitivity, Volume
- Can you hear it on 121.6?
- Needle suddenly flickers from left to right
- Passed ELT
- Other antennas
- No antenna

## Body Shielding the BEST method of beating reflections at close range

- Can use L-PerTM -
- Receiver or Transciever!
- 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
- Body blocks out the signal
- Called a NULL
- Null should be at your BACK

## Off-Frequency Tuning

- Decrease sensitivity when:
- Sensitivity (L-PerTM) 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 (radio)
- Shortening (radio) or removing (Little L-PerTM) 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

## Some Situations

## Airports

- Contact tower
- Access sometimes difficult
- Contact security or local PD
- Flashers or rotating beacons
- Monitor ground, CTAS or Tower freq if possible
- In a hanger?  Call FBO

## Marinas

- Big problem
- Masts and rigging of sailboats reflect signals
- Often, docks are locked up
- Get with harbor patrol if possible
- DF from down low
- Harbor patrol usually can contact the owner

## Private Homes

- Call IC
- Law Enforcement Support
- ESPECIALLY AFTER HOURS!
- Let them knock on doors
- Don’t ENTER
- Ask them to bring the unit to you

## Businesses after hours

- Notify IC
- If no emergency contact numbers at business - contact law enforcement or Fire Dept
- If you can’t find a contact number
- Send someone the next business day

## Government Agencies

- Military - bases, ships, and aircraft
- Other (police, fire, airport)

## Problems

- No Access
- Uncooperative people
- No law enforcement authority
- Signal disappears
- Signal leads you out of urban area
- Can’t find it
- Have the right road maps

## Signal Leads You Out of Urban Area

- Do not leave urban area
- Contact IC for guidance
- Issues include jurisdiction and safety of CAP personnel

## Field Exercises

## QUESTIONS?

## Slide 70