# Presentation: 513567

## ELTs: Everything You Wanted to know-and MOREBASIC GROUND ELT LOCATION COURSE (CLASSROOM)

**Notes:**
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 L-PerTM,” triangulation, body shielding, and activation of CAP.  This course is mainly focused on the ground team member aspect of electronic search.

## 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-PerTM Operation
- Triangulation
- Body shielding
- Aircraft coordination/LORAN/GPS operations
- Ground Vehicle Operations

## 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?

- 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)

**Notes:**
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. 

## What Will A Crashed Airplane Look Like?

**Notes:**
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)

## Air To Ground Coordination

- 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

- Weather
- Can’t pinpoint signal
- Row of hangers

## 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?

- 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

**Notes:**
AFRCC will try to resolve the ELT
AFRCC will call airport managers to see if they receive a signal that seems to be near an airfield
if a signal is received on the field, the manager will responsibly disable the ELT
If no airports are in the vicinity, a CAP search is initiated after a set period of time has passed
If the signal coincides with an overdue aircraft or unclosed flight plan, search begins faster
CAP 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.

## What if only an ELT signal 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

## Huh? 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

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

## Typical Aircraft ELT Operation

- 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?

- 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:

- 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?

- 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

## 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
- CAP Mission Coordinator plots these and assigns assets
- Ground teams must interpret for *land* navigation

## 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

**Notes:**
Diagram 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 uncommon
Food for thought: how common will the GPS portion of an ELT fail with the 121.5 beacon operating??  That’s anyone’s guess.

## System Review

- ELT, PLB, EPIRB Signal Received
- AFRCC gets coordinates from SARSAT
- Appropriate CAP Wing is activated

## 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 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

- 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

- 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-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 (**D**irect to the **F**lipping target)
- Turn at least one FULL circle, stopping and calling, “Center!”
- Check: Use **T**urn to **T**ell: the needle will point **D**irect to the **F**lipping target
- Use your compass, shoot an azimuth to get a bearing to the ELT

## Direct to the Flipping, Turn to Tell

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

## 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 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!

## Let’s See That

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

- Can use L-PerTM
- 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

- 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 (Jetstream)
- Shortening (Jetstream) 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

## 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 deflection generally indicates a signal that is strong enough 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

## 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 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

- 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-PerTM Operation
- Triangulation
- Body shielding
- Aircraft coordination/LORAN/GPS operations
- Ground Vehicle Operations

## QUESTIONS?