Emergency Position Indicating Radio Beacon

The ELT

•   Activated by g-force (when armed)
•   Some can be activated by the pilot in the cockpit
•   Three frequencies:
•   121.5 MHz (VHF emergency)
•   243 MHz (UHF emergency – military guard)
•   406 MHz (third generation advanced ELT/EPIRB/PLB)
•   General types:
•   General aviation aircraft
•   Military (“beepers” or “beacons”)
•   Marine EPIRB
•   Personal Locate Beacons (PLBs)
•   Advanced (406)
•   Test station (training practice beacon)

Types of Beacons
EPIRBs

•   406 MHz (w/ 121.5 homer)
•   Automatic activation when out of bracket and wet.
•   Floats upright to transmit
•   Strobe light
•   Min 48 hour transmit
•   Some GPS enabled

PLBs

•   406 MHz (w/ 121.5 homer)
•   Manual activation
•   Carried on persons
•   May or may not float
•   Held out of water to transmit
•   NO Strobe light required
•   Min 24 hour transmit
•   Some GPS Enabled

ELTs

•   Transmit on 121.5 (most) or 406 MHz
•   Integrated 121.5 MHz homer
•   Crash activation 
•   Floats upright to transmit
•   No Strobe light
•   Min 48 hour transmit

Initial ELT Detection

•   most ELTs were initially detected by the SARSAT-COSPAS system
•   This system no longer monitors 121.5 and 243.0
•   SARSAT-COSPAS only listens for 406 MHz signals now
•   Initial detection for an ELT must come from an airborne or surface-based asset
•   Airliners, military aircraft, ATC facilities
•   Participating civil traffic: YOU
•   Using the Area of Intersection method should get you closer, you may need mission staff to assist

Marine EPIRB

•   Emergency Position Indicating Radio Beacon
•   Similar to an ELT, an EPIRB is used on ships and boats
•   Mandatory on certain commercial vessels
•   Some activate automatically and others are manually activated
•   By law, all must be 406 capable now

Hex ID

•   EPIRB’s identification, when decoded into its 15 character hexadecimal representation, which is the EPIRB’s unique identifier number.
•   Normally readout in 3 groups of 5 characters.  Example:  ABCDE  12345 ABCDE

EPIRB Operational Requirements

•   EPIRB 406 MHz Signal  - 5 Watts
•   Short bursts at approximately 50 second intervals (varies between 47.5 and 52.5 s), with a transmission time of 440 ms or 520 ms.
•   Transmits in the 406.0 to 406.1 MHz band.
•   Transmission consists:
•   unmodulated carrier, for 160 ms,
•   short synchronization signal, signal inverted for test,
•   Digital message that provides stored information (identification, nationality, type of user),
•   Optionally, current information like, type of emergency and estimated location.

•   Strobe Light
•   Auxiliary Radio-Locating Device121.5 MHz, 25 mW, Warble, (a US Req.)
•   Self-test Function
•   Lanyard – 5 to 8 meters
•   Battery – 48hrs of continuous operation
•   Buoyancy and Stability – float upright
•   Designed to prevent inadvertent activation

EPIRB Control

•   Ready – EPIRB should be ON in the water unless in its bracket. Sometimes labeled “OFF”.
•   ON – EPIRB operates regardless of location or orientation.  Unconditional “ON” position. (Requires two physical actions)
•   Test – Self-test Function.

EPIRB Activation

What Happens;

•   Beacon starts transmitting its Unique Hex ID in a 406 MHz digital message,
•   121.5 MHz homer with an audible warble,
•   Strobe Light starts flashing.

Prevention of Inadvertent Activation

•   Must be fitted with means to prevent inadvertent activation and deactivation.
•   Not automatically activate when water washes over while in bracket.
•   Most EPIRBs use bracket with magnet to disable activation circuit.

EPIRB Deactivation

•   Remove beacon from water and dry off or replace in bracket
•   Move switch to OFF or Ready position
•   If the above failed then:
•   Remove cover and disconnect battery

EPIRB Self Test

•   Battery Voltage Check
•   Full Circuitry Check
•   Test Data burst
•   GPS acquisition Test (Self Locating)
•   Not required to check remaining power available in the battery.

Battery Replacement

•   Required at Expiration date or if EPIRB activated for any reason besides test.
•   Expiration of battery = ½ Useful Life.
•   Useful Life = power for all required testing + 48 hrs operation.

Types of Brackets

Category 1

•   Automatic Release  between 4 to 13 ft.
•   EPIRB is transmitting when it gets to the surface
•   Hydrostatic release needs replacement every two years.

Category 2

•   Manual Release
•   Wet sense deactivation magnet
•   No Bracket carriage requirement