1. EPIRB’s How They Work & DF-430 On the C-130H
Will cover:
How EPIRBS work
Some about your DF-430
Beacon Alerts in the CC
and some about false alerts
January 2010

2. How the System Works
L Yarbrough/D7 CFVS

3. LEOSAR & GEOSAR Satellites
GEOSAR Geostationary Satellites – 25,000 miles up. Same platform as weather satellites Beacon detect. No independent location data.
LEOSAR Low Earth Orbit Satellites miles up. Polar orbit, with all points in the foot print at least once every 100 minutes. Center path of footprint 17 minutes wide, needs three full transmissions to calculate Doppler location.
L Yarbrough/D7 CFVS

4. Maritime Distress Beacon
Types of Beacons
Maritime Distress Beacon
EPIRBs
406 MHz (w/ homer)
Automatic activation when out of bracket and wet.
Floats upright to transmit
Strobe light
Min 48 hour transmit
Some GPS enabled
L Yarbrough/D7 CFVS

5. Distress Beacon for Personal Use (Land Rescue)
Types of Beacons
Distress Beacon for Personal Use (Land Rescue)
PLBs
406 MHz (w/ 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
L Yarbrough/D7 CFVS

6. Aviation Distress Beacon
Types of Beacons
Aviation Distress Beacon
ELTs
Transmit on (most) or 406 MHz
Integrated MHz homer
Crash activation
Floats upright to transmit
No Strobe light
Min 48 hour transmit
L Yarbrough/D7 CFVS

7. Maritime Satellite Emergency Position-Indicating RadioBeacon EPIRB
L Yarbrough/D7 CFVS

8. 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 to 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.
Designed to prevent inadvertent activation
L Yarbrough/D7 CFVS

9. 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 ABCDE
HexID only uses 0 through 9 plus A through F.
L Yarbrough/D7 CFVS

10. Battery Replacement
Required at Expiration date or if EPIRB activated for any reason besides test.
Useful Life = power for all required testing + 48 hrs operation.
L Yarbrough/D7 CFVS

11. EPIRB Operational Requirements
Positive visual and/or audible indication that EPIRB is activated (strobe light flashing).
Easily manually deployed, activate, and deactivated, and transferred to survival craft.
Not be activated or deactivated by conditions encountered in maritime environment.
L Yarbrough/D7 CFVS

12. 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.
L Yarbrough/D7 CFVS

13. 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.
L Yarbrough/D7 CFVS

14. 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
L Yarbrough/D7 CFVS

15. EPIRB Activation How Or By definition it transmits:
out of bracket and wet,
by manual switch, in or out of bracket, Or
Self test
L Yarbrough/D7 CFVS

16. 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.
Beacon will not start transmissions until one full timing cycle has elapsed (+50 sec). Some with GPS will wait up to 5 minutes to allow for GPS position acquisition.
L Yarbrough/D7 CFVS

17. Rockwell Collins DF-430

18. DF-430 Bearings Bearing are relative Bearing Accuracy – less than 3°
(Heads up, not compass).
Bearing Accuracy – less than 3°
Bearing Stability - +/- 5° (means less needle swing, a more stable point)
Bearing Range – continuous 360°
L Yarbrough/D7 CFVS

19. Bearing Inhibit
Bearing Inhibit – during on-board transmission, the bearing computation is frozen (DF LOCK is displayed during on-board transmissions)
L Yarbrough/D7 CFVS

20. SLDMBs ARGOS (401.650) is the frequency for your SLDMB.
L Yarbrough/D7 CFVS

21. DF Bearing Pointer
DF pointer only updates on receipt of next 406 MHz EPIRB burst transmission.
Will seem jerky.
EPIRB transmission only every ~50 sec.
Burst transmission only half sec duration.
Bust transmission is just a short (.5 sec) buz in the headset.
L Yarbrough/D7 CFVS

22. Figure-of-Merit (FOM) Values
DF-430 will display a FOM value in range of
Practical application is as a secondary level of confidence the aircraft is tracking towards target.
L Yarbrough/D7 CFVS

23. 406 MHz Detection Range Altitude (ft) Detection Range (nm) 25,000 133
22,500
129
20,000
124
17,500
119
15,000
113
12,500
106
10,000 99
7,500 88
5,000 76
2,500 57
1,500 23
L Yarbrough/D7 CFVS

24. Operational Considerations
Transit in SAR Scan, unless tasking indicates a need to monitor a tactical freq.
Greatest range/ earliest detection opportunity at higher altitudes.
If a 406 signal is detected, DF needle will point.
L Yarbrough/D7 CFVS

25. 406 Beacon Tests
Every 406 MHz Beacon is supposed to be tested (using the self-test function) once every month.
Each test transmits one live 406 burst.
Wait at least two bursts before you react to a 406 Det.
L Yarbrough/D7 CFVS

26. What Does the CC/RCC do with a 406 Alert?
EPIRB Prosecution
What Does the CC/RCC
do with a 406 Alert?

27. Registered/Unlocated 406MHZ EPIRB
1. RCC or RSC on receipt of unlocated registered 406 EPIRB:
a. Place case in the DISTRESS phase.
b. Assume SMC.
c. Determine status of vessel from contact number listed, available databases, etc.
L Yarbrough/D7 CFVS

28. Registered/Unlocated 406MHZ EPIRB (cont)
2. If vessel is determined to be safe underway or in port:
a. Close case. A case will be claimed for all 406 alerts prosecuted
L Yarbrough/D7 CFVS

29. Registered/Unlocated 406MHZ EPIRB (cont)
3. If vessel is underway and cannot be contacted:
a. Issue UMIB for Home Port and general area in which vessel is believed to be operating.
b. Contact AMVER Ships and request callouts for the vessel.
c. Contact USMCC and request satellite forecast for the geographic area.
L Yarbrough/D7 CFVS

30. Registered/Unlocated 406MHZ EPIRB (cont)
3. If vessel is underway and cannot be contacted:
d. If the next forecast satellite pass does not locate the beacon consider sending an SRU to the area to attempt to hail the vessel or DF on 406/121.5MHZ homing signal. Continue investigating to try to determine last known position/probable track of vessel for additional searches.
L Yarbrough/D7 CFVS

31. Registered/Unlocated 406MHZ EPIRB (cont)
3. If vessel is underway and cannot be contacted:
e. If vessel cannot be located after reasonable search is conducted, search will be suspended.
L Yarbrough/D7 CFVS

32. Registered/Unlocated 406MHZ EPIRB (cont)
4. If SRU is tasked to search for vessel:
a. Proceed to LKP/tasked search area. Make callouts for vessel and attempt to DF homing beacon on 406/121.5MHZ.
L Yarbrough/D7 CFVS

33. Registered/Unlocated 406MHZ EPIRB (cont)
4. If SRU is tasked to search for vessel:
b. If signal cannot be DF’d once on scene and unless otherwise tasked, aircraft shall complete a VS search at radius of 12NM. Vessels shall complete the same search at 3NM.
L Yarbrough/D7 CFVS

34. “A” solution located 406MHZ EPIRB
1. RCC or RSC on receipt “A” solution located 406MHZ EPIRB:
a. Place case in the DISTRESS phase.
b. Assumed SMC.
c. Determine status of vessel from contact number listed (if registered), available databases, etc.
L Yarbrough/D7 CFVS

35. “A” solution located 406MHZ EPIRB (cont)
2. RCC or RSC if vessel is determined to be safe/underway or in port:
a. Close case.
L Yarbrough/D7 CFVS

36. “A” solution located 406MHZ EPIRB (cont)
3. RCC or RSC if vessel is underway and cannot be contacted:
a. Issue UMIB for general area in which vessel is believed to be operating.
b. Contact AMVER ships in vicinity and request callouts for vessel.
c. Dispatch SRU to located vessel and determine status. SRU’s should be tasked to DF on the signal.
L Yarbrough/D7 CFVS

37. “A” solution located 406MHZ EPIRB (cont)
3. RCC or RSC if vessel is underway and cannot be contacted:
d. If vessel cannot be located after reasonable
search is conducted, search will be suspended.
L Yarbrough/D7 CFVS

38. “A” solution located 406MHZ EPIRB (cont)
4. SRU if tasked to search for vessel:
a. Proceed to position/tasked search area. Make callouts for vessel and attempt to DF homing beacon on 406/121.5MHZ.
b. If a signal cannot be DF’d once on scene and unless otherwise tasked, aircraft shall complete a VS search at radius of 12NM. Vessels shall complete the same search at 3NM.
L Yarbrough/D7 CFVS

39. “B” solution with alert probability less than or equal to 20%
1. RCC or RSC on receipt “B” solution with probability less than or equal to 20%:
Place case in the UNCERTAINTY phase.
Assume SMC.
Coordinate investigation with RCC responsible for “A” solution. If investigation determines “B” solution is the likely position, respond in same manner as an “A” solution.
L Yarbrough/D7 CFVS

40. “B” solution with alert probability greater than 20%
1. RCC or RSC on receipt “B” solution with probability greater than 20%:
a. Place case in the ALERT phase.
b. Assumed SMC.
c. Coordinate investigation with RCC responsible for “A” solution. If investigation determines “B” solution is the likely position, respond in same manner as an “A” solution.
L Yarbrough/D7 CFVS

41. Unregistered/Unlocated EPIRB alerts:
1. RCC or RSC investigate identity of vessel through vessel data bases.
2. RCC or RSC contact RCC country of vessel registered and attempt to determine vessel’s status.
L Yarbrough/D7 CFVS

42. False Alerts

43. False Alerts
If a false alert is determined upon arrival on-scene complete the following actions:
Have vessel de-activate the beacon.
Have vessel provide the beacon “HexID”
Have vessel provide the reason beacon alerted and include in MISLE Reporting.
Advise vessel that EPIRB and bracket require servicing and battery replacement.
Relay to tasking authority as required.
L Yarbrough/D7 CFVS

44. Operator Induced False Alerts
10% were Testing without following manufactures instructions, or other deliberate non-emergency activations
6% were EPIRBs deliberately taken out of bracket and naked of any control of the wet sensor.
13 were stored or transported out of their bracket (Naked) by the owner. They were in ditch bags, car trunks, garages, chart drawers, etc.
L Yarbrough/D7 CFVS

45. EPIRB False Alerts
69% Caused by Failure of “The bracket decoupling function” to control the EPIRB
Manufactures, makes and models in the US registration data base were proportionally represented by False Alerts
These false activations tend to be transitory or short duration events.
I assume the bracket decoupling function gained control of the beacon and stopped the transmission in a short period of time.
L Yarbrough/D7 CFVS

46. Why didn’t I get a 406 Detection or How Long do False Alerts Last?
This slide is a study of the elapsed time from first detection to last detection. Each bar on the graph represents the number of alerts.
The red line shows the cumulative % of False Alerts who’s duration was less than the duration time points selected.
As this slide illustrates, most EPIRBs (70%) had stopped transmitting an alert before there was an opportunity for the owner to notified and take action to secure the beacon (about 30minutes).
40 or 17% had a total detection time of less than 1 minute.
77 or 33% had a detection time of >5 minutes, and
105 or 45% were detection events lasting less than 10 minutes.
L Yarbrough/D7 CFVS

47. Questions? (305) 415 6868 Larry.T.Yarbrough@uscg.mil
L Yarbrough/D7 CFVS