distress radiobeacon

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Distress radiobeacon

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Emergency position-indicating radio beacons or EPIRBs

Distress radio beacons, also known as emergency beacons, PLB, ELT orEPIRB, are trackingtransmitters which aid in the detection and location ofboats, aircraft, and people in distress. Strictly,they are radiobeaconsthat interface with worldwide offered service ofCospas-Sarsat, theinternational satellite system forsearch and rescue (SAR). When manually activated, orautomatically activated upon immersion, such beacons send out a distress signal. The signals aremonitored worldwide and the location of the distress is detected by non-geostationarysatellites, andcan be located by some combination ofGPStrilateration and dopplertriangulation.[1]

The basic purpose of a distress radiobeacon is to help rescuers find survivors within the so-called"golden day"[2] (the first 24 hours following a traumatic event) during which the majority ofsurvivors can usually be saved.

Since the inception of Cospas-Sarsat in 1982, distress radiobeacons have assisted in the rescue ofover 28,000 people in more than 7,000 distress situations. [3] In 2010 alone, the System providedinformation which was used to rescue 2,388 persons in 641 distress situations. [4]

Contents

1 General description

2 Classification nomenclature

3 Beacon modes

o 3.1 Digital mode: 406 MHz beacons 3.1.1 406 MHz beacon facts 3.1.2 Hex codes

o 3.2 AIS SART

o 3.3 Analog mode: all other beacons

4 Frequency

o 4.1 Cospas-Sarsat (satellite) compatible beacon frequencies

o 4.2 Cospas-Sarsat incompatible beacon frequencies

5 Types

o 5.1 EPIRB sub-classification

o 5.2 ELT sub-classification

o 5.3 PLB sub-classification
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6 Activation methods

7 Advantages and disadvantages of the various beacons

8 Phase-out of 121.5 & 243 beacons

9 SAR response to various beacons

10 Responsible agencies

11 Statutory requirements

o 11.1 Registration 12 Environment-specific requirements

o 12.1 Aviation (ELTs)

o 12.2 Marine (EPIRBs)

o 12.3 Personal locator beacons (PLBs)

13 Detailed type descriptions

o 13.1 Current types

13.1.1 EPIRBs (marine) 13.1.2 ELTs (aircraft) 13.1.3 PLBs

o 13.2 Obsolete types

13.2.1 Obsolete EPIRBs 13.2.2 Obsolete ELTs

13.2.3 Obsolete PLBs 14 How they work

15 GPS-based, registered

16 High-precision registered

17 Traditional ELT, unregistered

18 Location by Doppler (without GPS)

19 Operational testing

20 Satellites used

21 History 22 Current events

23 Alternative technologies

o 23.1 GPS aircraft tracking

o 23.2 TracMe

o 23.3 APRS

24 See also

25 Notes

26 References

27 External links

General description

Most beacons are brightly colored and waterproof. EPIRBs and ELTs are larger, and would fit in acube about 30 cm (12 in) on a side, and weigh 2 to 5 kg (4 to 11 lb). PLBs vary in size fromcigarette-packet to paperback book and weigh 200 g to 1 kg ( to 2 lb). They can be purchasedfrom marine suppliers, aircraft refitters, and (in Australia and the United States) hiking supplystores. The units have a useful life of 10 years, operate across a range of conditions (40C/F to+40C/+104F), and transmit for 24 to 48 hours.[5] The cost of radiobeacons varies according to

performance and specifications.
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beacon#APRShttp://en.wikipedia.org/wiki/Distress_radiobeacon#See_alsohttp://en.wikipedia.org/wiki/Distress_radiobeacon#Noteshttp://en.wikipedia.org/wiki/Distress_radiobeacon#Referenceshttp://en.wikipedia.org/wiki/Distress_radiobeacon#External_linkshttp://en.wikipedia.org/wiki/Celsiushttp://en.wikipedia.org/wiki/Fahrenheithttp://en.wikipedia.org/wiki/Distress_radiobeacon#cite_note-5


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Classification nomenclature

The three distress radiobeacon types are further classified as follows:[6]

There are three types of distress radio beacons compatible with the Cospas-Sarsat system: [6]

EPIRBs (emergency position-indicating radio beacons) signal maritime distress.

ELTs (emergency locator transmitters) signal aircraft distress.

PLBs (personal locator beacons) are for personal use and are intended to indicate a person

in distress who is away from normal emergency services; e.g., 9-1-1. They are also used forcrewsaving applications in shipping and lifeboats at terrestrial systems. InNew SouthWales, some police stations and theNational Parks and Wildlife Serviceprovide personallocator beacons to hikers for no charge.[7]

Beacon modes

The most important aspect of a beacon in classification is the mode of transmission. There are twovalid transmission modes: digital and analog. Where digital usually has a longer range, analog ismore reliable. Analog beacons are useful to search parties and SAR aircraft, though they are nolonger monitored by satellite.

Digital mode: 406 MHz beacons

406 MHz beacons transmit bursts of digital information to orbiting satellites, and may also contain asmall integrated analog (121.5 MHz) homing beacon. They can be uniquely identified (viaGEOSAR). Advanced beacons encode a GPS orGLONASS position into the signal. All beacons

are located by doppler trangulation to confirm the location. The digital data identifies the registereduser. A phone call by authorities to the registered phone number often eliminates false alarms (falsealarms are the typical case). If there is a problem, the beacon location data guides search and rescueefforts. No beacon is ignored. Anonymous beacons are confirmed by two doppler tracks before

beginning beacon location efforts.

The distress message transmitted by a 406 beacon contains the information such as:

Which country the beacon originates from.

A unique 15-digit hexadecimal beacon identification code (a "15-hex ID").

The encoded identification of the vessel or aircraft in distress, either as an MMSI value, or

as, in the case of an ELT, either the aircraft's registration or its ICAO 24-bit address (fromits Mode-S transponder).

When equipped, a GPS position.

Whether or not the beacon contains a 121.5 MHz homing transmitter.

The digital distress message generated by the beacon varies according to the above factors and isencoded in 30 hexadecimal characters. The unique 15-character digital identity (the 15-hex ID) ishard-coded in the firmware of the beacon. The 406.025 MHz carrier signal is modulated plus orminus 1.1 radians with the data encoded using Manchester encoding, which ensures a net zero

phase shift aiding Doppler location [8]

406 MHz beacon facts
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406 MHz beacons transmit for a quarter of a second immediately when turned on, and then

transmit a digital burst once every 50 seconds thereafter. BothGEOSARand LEOSARsatellites monitor these signals.

406 MHz beacons will be the only beacons compatible with the MEOSAR(DASS) system.[9]

406 MHz beacons must be registered (see below).

Hex codes

Example hex codes look like the following: 90127B92922BC022FF103504422535 [10]

A bit telling whether the message is short (15 hex digits) or long (30 hex digits) format.

A country code, which lets the worldwide COSPAS/SARSAT central authority identify the

national authority responsible for the beacon. Embedded 15-Hex ID or 15-hex transmitted distress message, for example,

2024F72524FFBFF The hex ID is printed or stamped on the outside of the beacon and ishard-coded into its firmware. The 15-hex ID can only be reprogrammed by certified distress

radiobeacon technicians. The national authority uses this number to look up phone numbersand other contact information for the beacon. This is crucial to handle the large number offalse alarms generated by beacons.

A location protocol number, and type of location protocol: EPIRB or MMSI, as well as all

the data fields of that location protocol. If the beacon is equipped withGPS orGLONASS, arough (rounded) latitude andlongitude giving the beacon's current position. In some aircraft

beacons, this data is taken from the aircraft's navigation system. When a beacon is sold to another country, the purchaser is responsible for having the beacon

reprogrammed with a new country code and to registerit with his/her nation's beaconregistry, and the seller is responsible to de-registerthe deprecated beacon ID with his/her

national beacon registry. One can use the beacon decoder web page[11]at Cospas-Sarsat to decrypt/extract the 15-hex

ID from the 30-hex distress message.

AIS SART

Main article: AIS-SART

These devices are similar to traditional SAR radar transponders (SART), which additionally includea GPS receiver and a transmitter on VHFAIS channels, so they show up on ship AIS receivers.They are lightweight and can be used to equip inflatable liferafts.

Analog mode: all other beacons

A simple analog siren tone is transmitted continuously until the battery dies.

In the case of 121.5 MHz beacons, the frequency is monitored by most commercial airliners.

The Cospas-Sarsat system detected this type of beacon prior to 1 February 2009 when a

LEOSAR satellite was in view of both the beacon and anLEOLUT(satellite dish). Satellitedetection of 121.5 MHz beacons ceased on 1 February 2009 (see below).

Frequency
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Distress beacons transmit distress signals on the following key frequencies; the frequency useddistinguishes the capabilities of the beacon. A recognizedbeacon can operate on one of the three(currently) Cospas-Sarsat satellite-compatible frequencies. In the past, other frequencies were alsoused as a part of the search and rescue system.

Cospas-Sarsat (satellite) compatible beacon frequencies

406 MHz UHF- carrier wave at 406.025 MHz 0.005 MHz[6]

Cospas-Sarsat incompatible beacon frequencies

Marine VHF radio channels 15/16 these channels are used only on the obsolete Class C

EPIRBs The obsolete Inmarsat-E beacons transmitted toInmarsat satellites on 1646 MHz UHF.

121.5 MHz VHF 6 kHz (frequency band protected to 50 kHz)[12] (Satellite detection

ceased on 1 February 2009,[13] but this frequency is still used for short-range location duringa search and rescue operation)

243.0 MHz VHF 12 kHz (frequency band protected to 100 kHz) [12][14] (prior to 1

February 2009 COSPAS-SARSAT Compatible)

Types

The type of a beacon is determined by the environment for which it was designed to be used:

EPIRBs (Emergency Position Indicating Radio Beacons) signal maritime distress,

ELTs (Emergency Locator Transmitters) signal aircraft distress

PLBs (Personal Locator Beacons) are for personal use and are intended to indicate a

person in distress who is away from normal emergency services

Each type is sub-classified:

EPIRB sub-classification

EPIRBS are sub-classified as follows:[15]

Recognized categories:

Category I 406/121.5 MHz. Float-free, automatically activated EPIRB. Detectable bysatellite anywhere in the world. Recognized by GMDSS.

Category II 406/121.5 MHz. Similar to Category I, except is manually activated. Some

models are also water activated.

Unrecognized classes:

Class A 121.5/243 MHz. Float-free, automatically activating. These devices have beenphased out by the U.S. Federal Communications Commission (FCC) and are no longerrecognized.

Class B 121.5/243 MHz. Manually activated version of Class A. These devices have been

phased out by the FCC and are no longer recognized.
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Class S 121.5/243 MHz. Similar to Class B, except it floats, or is an integral part of a

survival craft (lifeboat). These devices have been phased out by the FCC and are no longerrecognized.

Class C Marine VHF ch15/16. Manually activated, these beacons operate on maritime

channels only, and therefore are not detectable by satellite or normal aircraft. These devices

have been phased out by the FCC and are no longer recognized.

Inmarsat-E This service ended 1 December 2006; all former users have switched to

Category I or II 406 MHz EPIRBS. These beacons were float-free, automatically activatedEPIRBs operated on 1646 MHz. They were detectable by Inmarsat geostationary satellites,and were recognized by GMDSS. See Inmarsat-E.

ELT sub-classification

ELTs for aircraft may be classed as follows:[16]

A ELT, automatically ejected

AD ELT, automatic deployable

F ELT, Fixed

AF ELT, automatic fixed

AP ELT, automatic portable

W ELT, water activated

S ELT, survival

Within these classes, an ELT may be either a digital 406 MHz beacon, or an analog beacon (seeabove).

PLB sub-classification

There are two kinds of PLB:

PLB with GPS input (internal or external)

PLB with no GPS input

All PLBs transmit in digital mode on 406 MHz.

Activation methodsThere are two ways to activate a beacon:

manually, or

automatically

Automatic EPIRBs are water activated, while automatic ELTs are G-force(impact) activated. SomeEPIRBs also deploy; this means that they physically depart from their mounting bracket on theexterior of the vessel (usually by going into the water.)
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For a marine EPIRB to begin transmitting a signal (or "activate") it first needs to come out of itsbracket (or "deploy"). Deployment can happen either manually where someone has to physicallytake it out of its bracket or automatically where water pressure will cause a hydrostatic releaseunit to release the EPIRB from its bracket. If it does not come out of the bracket it will not activate.There is a magnet in the bracket which operates a reed safety switch in the EPIRB. This is to

prevent accidental activation when the unit gets wet from rain or shipped seas.

Once deployed, EPIRBs can be activated, depending on the circumstances, either manually(crewman flicks a switch) or automatically (as soon as water comes into contact with the unit's "sea-switch".) All modern EPIRBs provide both methods of activation and deployment and thus arelabelled "Manual and Automatic Deployment and Activation."

Advantages and disadvantages of the various beacons

Analog (121.5 MHz) Beacons Digital (406 MHz) Beacons

SAR response delay SAR response delay

SAR response to anonymous

beacons can be delayed 46 hours,and as much as 12 hours.[17]

Resolution or response to registered beacons isvery swift. SAR response can be activated withinapproximately 10 minutes of beacon activation(and GEOSAR detection) if distress is evident.

Unregistered beacons can usually be responded

to after only 1 LEOSAR satellite pass; after twopasses, response is immediate.

False alerts False alerts

False alerts may result in a long and

fruitless search by costly SARassets, although rescue co-ordination centres typically analysethe circumstances, consideringlocation, movement of the sourceand confirmatory reports beforelaunching an operation[citation needed]

o Searches for interference

signals and false alertsinhibit SAR assets from

being available for realsearches

All alerts (100%) come from beacons (analog

interference is ignored). Approximately 7 out of 10 false alerts are

resolved by a phone or radio call, therefore,o SAR resources are not wasted

o SAR assets are more available for actual

distresso Persons responsible for causing false

alerts can avoid having to pay fines orpaying the costs of operating SAR assets

o Follow-up to false activations allows

continuous reductions in the number offalse alerts

Information transmitted by the beacon Information transmitted by the beacon

Anonymous siren tone

A unique 15, 22, or 30 digit serial number called

aHex Code is transmitted The Hex Code can contain a plethora of

information, such as:[18]o the Country of beacon registration

o the identification of the vessel or aircraft

in distress, and Identification for aircraft ELTs

can be in the form of the aircraft's
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callsign or its ICAO 24-bitaddress (from its Mode-Stransponder)

o optionally, position data from onboard

navigation equipment (GPS)

Beacon registration information Beacon registration information

Anonymous beacons cannot be registered

There is no charge to register 406 beacons (see

below).[15]o Unless otherwise advised, personal

information is used exclusively for SARdistress alert resolution purposes

Hex Code registration is mandatory in most

countries of the world[citation needed]

Beacons are registered with MCCs who have 24-

hour access to registry data, such as:o Name of the owner of the beacon

o Name or callsign of the ship, aircraft, or

other vehicle the beacon is associatedwith

o Cellular, MMSI, pager numbers, or other

contact information

Transmission power Transmission power

0.1 W continuous weak signal cannotusually penetrate debris or trees

5 W pulse mode strong pulse reaches the satellites

Potential to be seen by a satellite Potential to be seen by a satellite

No detection by search and rescue satellites(coverage ended February 2009)

GEOSAR provides nearly-instantaneouscoverage 70 degrees north and south of theequator

Worldwide coverage via LEOSAR 6 satellites

o For 406 signals, LEOSARs do not have

to be in sight of a LUT to relay a distressmessage to Cospas-Sarsat. Once a 406signal is detected by a satellite, thesatellite will "dump" this data towardsEarth (thus to all LUTs) for 24 hours.

Future use ofGNSS satellites will allow

worldwide real-time coverage (MEOSAR)

Location detection Location detection

No detection by search and rescue satellites(coverage ended February 2009)

If a 121.5 MHz beacon signal is detectedby a ground station or by an aircraft withinrange, the signal can be located through theuse of specialized radio direction-finding

equipment dispatched to the area, or by a

LEOSAR uses same technique as for analog

beacons, but, since beacons are uniquelyidentified as beacons and have improvedfrequency stability, response can occur based onfirst-pass information[19]

Doppler-only accuracy is within 5 km (3 mi)

that is, the position is sufficiently accurate for

SAR purposes even after only one pass. What's
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trained operator using a radio receivertuned to 121.5 MHz (VHF/AMaeronautical band).

more, the "A-position" (the most likely of thetwo 'mirror' positions) can be determined validwith 98.5% accuracy after only one satellite

pass.o This accuracy can be increased to 99.3%

using so-called "combined Leo-Geo

processing,"[20] and this technique alsoenables accurate positions to begenerated with as little as two or three

bursts from the beacon (i.e. less than 4minutes of transmission) and thus greatlyincreases the chances of being foundeven if the beacon is ultimatelyconsumed by fire or is otherwisedestroyed

GPS Position can be encoded into the Hex Code

and can be updated real-time via GEOSARo Encoded GPS position accuracy is about

15 m (45 ft), however, the space in thehex message protocol for positioninformation is limited, so transmittedaccuracy is approximately +/- 125 metres

Increases in accuracy are a significant

improvement over analog beacons from twopossible positions within a 20 km (12 mi) radius,to 15m accuracy at one position; animprovement in accuracy of over 2500.

o The improvements in accuracy are

largely responsible for the advent of thephrase "taking the 'search' out of Searchand Rescue"

LEOSAR Doppler triangulation is less affected

by beacon movement due to improved frequencystability

In the future, near-instantaneous detection &

position triangulation via MEOSAR

Age of technology Age of technology

121.5 MHz beacons were developed in thelate 1960s, when car phones weighedroughly 20 lb (the first ELT TSO C91 waswritten in 1971)[21]

406 MHz beacons use proven, modern technologiesreminiscent of those found in modern cell phones.

See also Cospas-Sarsat Advantages of 406 Beacons and Canada's National Search and RescueSecretariat Advantages of 406 Beacons

Although modern systems are significantly superior to older ones, even the oldest systems providean immense improvement in safety, compared to not having any beacon whatsoever.
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Phase-out of 121.5 & 243 beacons

Since 1 February 2009, only 406 MHz beacons are detected by the international Cospas-SarsatSARsatellite system. This affects all maritime beacons (EPIRBs), all aviation beacons (ELTs) and all

personal beacons (PLBs). In other words, Cospas-Sarsat has ceased satellite detection andprocessing of 121.5/243 MHz beacons. These older beacons are now only detectable by ground-based receivers and aircraft.

121.5 and 243.0 MHz EPIRBs are banned on boats in the United States [22] and in many otherjurisdictions. More information about the switch to 406 is available on Cospas-Sarsat's 121.5/243Phase-Out page.

Despite the switch to 406 MHz, pilots and ground stations are encouraged to continue to monitorfor transmissions on the emergency frequencies, as many 406 beacons are also equipped with 121.5"homers." Furthermore, the 121.5 MHz frequency continues to be used as a voice distress frequency(especially in aviation).

SAR response to various beacons

Emergency beacons operating on 406 MHz transmit a unique 15, 22, or 30 character serial numbercalled a Hex Code. When the beacon is purchased the Hex Code should be registered with therelevant national (or international) authority. Registration provides Search and Rescue agencieswith crucial information such as:

phone numbers to call,

a description of the vessel, aircraft, vehicle, or person (in the case of a PLB)

the home port of a vessel or aircraft

any additional information that may be useful to SAR agencies

Registration information allows SAR agencies to start a rescue more quickly. For example, if ashipboard telephone number listed in the registration is unreachable, it could be assumed that a realdistress event is occurring. Conversely, the information provides a quick and easy way for the SARagencies to check and eliminate false alarms (potentially sparing the owner of the beacon significantfalse alert fines.)

An unregistered 406 beacon still carries some information, such as the manufacturer and serialnumber of the beacon, and in some cases, anMMSI or aircraft tail number/ICAO 24-bit address.

Despite the clear benefits of registration, an unregistered 406 beacon is very substantially betterthan a 121.5/243.0 beacon; this is because the Hex Code received from a 406 beacon confirms theauthenticity of the signal as a real SAR alert.

Modulation of a radio beacon of distress
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Menu

0:00Transmission of a distress radiobeacon on 121.5 MHz and 243 MHz

Problems playing this file? See media help.

Beacons operating on 121.5 and 243.0 MHz only simply transmit an anonymous siren tone, andthus carry no information to SAR agencies. Such beacons now rely solely on the terrestrial oraeronautical monitoring of the frequency. In the UK, the Distress and Diversion Cell of the RoyalAir Force provides continuous monitoring of 121.5 and 243.0 MHz, with autotriangulation from anetwork of terrestrial receivers on both frequencies. In Canada, only air traffic service stations(control towers or flight service facilities) monitor 121.5 MHz during operating hours. Overflyingcommercial or private aircraft monitor 121.5 MHz only if equipped with a suitable receiver, and iftime/courtesy permits; monitoring 121.5 MHz is not mandatory. SAR authorities have no way ofknowing whether a 121.5/243.0 MHz signal is actually a SAR signal until they physically deploy tothe location and home in on the source (and sound) of the transmission. Since SAR resources arescarce (and expensive), most countries do not deploy the most useful SAR homing assets (aircraft)until ambiguity has been resolved (see doppler).

Responsible agencies

File:Eltsearch.JPGCivil Air Patrol members practice searching for an emergency locator transmitter. The member infront is using a manual radio direction finder.

The examples and perspective in this section deal primarily with USA and do notrepresent aworldwide view of the subject. Please improve this article and discuss the

issue on thetalk page.(September 2012)

In the U.S. the Coast Guard investigates offshore beacons and rescues victims. On-shore beaconsare investigated by local search-and-rescue services in Alaska. The Air Force Rescue CoordinationCenterresponds to land-based emergency signals, usually dispatching volunteer members from theUnited States Air Force Auxiliary Civil Air Patrol. In the U.S. there are no published notificationsystems for other locations.

Statutory requirements

InNorth America and Australasia (and most jurisdictions in Europe) no special license is requiredto operate an EPIRB. In some countries (for example the Netherlands[23]) a marine radio operatorslicense is required. The following paragraphs define other requirements relating to EPIRBs, ELTs,and PLBs.

Registration

All distress alerting beacons operating on 406 MHz should be registered; all vessels and aircraftoperating underInternational Convention for the Safety of Life at Sea (SOLAS) and InternationalCivil Aviation Organization (ICAO) regulations must register their beacons. Some nationaladministrations (including the United States, Canada, Australia, and the UK) also requireregistration of 406 MHz beacons.
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There is no charge to register 406 MHz beacons.

The U.S. Coast Guard warns that a user's "life may be saved as a result of registeredemergency information" because it can respond more quickly to signals from registered

beacons.[15]

Unless the national registry authority advises otherwise, personal information contained in a

beacon is used exclusively for SAR distress alert resolution purposes.

The Cospas-Sarsat Handbook of Beacon Regulations provides the status of 406 MHz beaconregulations in specific countries and extracts of some international regulations pertaining to406 MHz beacons.

The following list shows the agencies accepting 406 beacon registrations by country:

United States National Oceanic and Atmospheric Administration

Canada Canadian Beacon Registry, CFB Trentonfor civil beacons, CMCC for military

beacons Australia Australian Maritime Safety Authority (AMSA)

the United Kingdom United Kingdom Maritime and Coastguard Agency(MCA) Greece Ministry of Merchant Marine and Hellenic Civil Aviation Authority

France CNES

Netherlands Agentschap Telecom (NL)

International Cospas-Sarsat International 406 MHz Beacon Registration Database (IBRD)

Environment-specific requirements

Aviation (ELTs)

Most general aviation aircraft in the U.S. are required to carry an ELT, depending upon the type orlocation of operation, while scheduled flights by scheduled air carriers are not. However, incommercial aircraft, a cockpit voice recorderorflight data recordermust contain anUnderwaterlocator beacon.

As per14 CFR 91.207.a.1, ELTs built according to TSO-C91 (of the type described below as"Traditional ELT, unregistered") have not been permitted for new installations since June 21, 1995;the replacing standard was TSO-C91a. Furthermore, TSO-C91/91a ELTs are being replaced /supplemented by the TSO C126 406 MHz [24] ELT, a far superior unit.[21]

Although monitoring of 121.5 and 243 MHz (Class B) distress signals by satellite ceased inFebruary 2009, the FAA has not mandated an upgrade of older ELT units to 406 in United Statesaircraft.[25] Transport Canada has put forward a proposed regulatory requirement that requiresupgrade to Canadian registered aircraft to either a 406 MHz ELT or an alternate means system;however, elected officials have overruled the recommendation of Transport Canada for theregulation and have asked for a looser regulation to be drafted by Transport Canada. [26][27] Recentinformation indicates Transport Canada may permit private, general aviation flight with only anexisting 121.5 ELT if there is a placard visible to all passengers stating to the effect that the aircraftdoes not comply with international recommendations for the carriage of the 406 MHz emergencyalerting device and is not detectable by satellites in the event of a crash.[28]

Marine (EPIRBs)
http://en.wikipedia.org/wiki/Distress_radiobeacon#cite_note-autogenerated1-15http://www.cospas-sarsat.org/Documents/handbookOfBeaconRegs.htmhttp://en.wikipedia.org/wiki/National_Oceanic_and_Atmospheric_Administrationhttp://canadianbeaconregistry.forces.gc.ca/Logon.asp?lang=ehttp://en.wikipedia.org/wiki/CFB_Trentonhttp://en.wikipedia.org/wiki/CFB_Trentonhttps://www.nss.gc.ca/sar_directory/orgDetails_e.asp?org_id=139http://en.wikipedia.org/wiki/Australian_Maritime_Safety_Authorityhttp://en.wikipedia.org/wiki/United_Kingdom_Maritime_and_Coastguard_Agencyhttp://en.wikipedia.org/wiki/United_Kingdom_Maritime_and_Coastguard_Agencyhttp://www.yen.gr/http://en.wikipedia.org/wiki/Hellenic_Civil_Aviation_Authorityhttp://en.wikipedia.org/wiki/CNEShttp://www.agentschaptelecom.nl/onderwerpen/scheepvaart/Beroepsvaart/Radionoodbakens/Personal+Locator+Beaconhttp://www.406registration.com/http://en.wikipedia.org/wiki/Cockpit_voice_recorderhttp://en.wikipedia.org/wiki/Flight_data_recorderhttp://en.wikipedia.org/wiki/Flight_data_recorderhttp://en.wikipedia.org/wiki/Underwater_locator_beaconhttp://en.wikipedia.org/wiki/Underwater_locator_beaconhttp://en.wikipedia.org/wiki/Underwater_locator_beaconhttp://ecfr.gpoaccess.gov/cgi/t/text/text-idx?c=ecfr&sid=bb1f41f4b3694bd4e3089bd9bfa27d0f&rgn=div8&view=text&node=14:2.0.1.3.10.3.7.4&idno=14http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgTSO.nsf/0/e2b1e589c98200f886256dc900695b8c/$FILE/C91a.pdfhttp://en.wikipedia.org/wiki/Distress_radiobeacon#Traditional_ELT.2C_unregisteredhttp://en.wikipedia.org/wiki/Distress_radiobeacon#cite_note-24http://en.wikipedia.org/wiki/Distress_radiobeacon#cite_note-autogenerated7-21http://en.wikipedia.org/wiki/Distress_radiobeacon#cite_note-autogenerated7-21http://en.wikipedia.org/wiki/Distress_radiobeacon#cite_note-25http://en.wikipedia.org/wiki/Distress_radiobeacon#cite_note-26http://en.wikipedia.org/wiki/Distress_radiobeacon#cite_note-27http://en.wikipedia.org/wiki/Distress_radiobeacon#cite_note-28http://en.wikipedia.org/wiki/Distress_radiobeacon#cite_note-28http://en.wikipedia.org/wiki/Distress_radiobeacon#cite_note-autogenerated1-15http://www.cospas-sarsat.org/Documents/handbookOfBeaconRegs.htmhttp://en.wikipedia.org/wiki/National_Oceanic_and_Atmospheric_Administrationhttp://canadianbeaconregistry.forces.gc.ca/Logon.asp?lang=ehttp://en.wikipedia.org/wiki/CFB_Trentonhttps://www.nss.gc.ca/sar_directory/orgDetails_e.asp?org_id=139http://en.wikipedia.org/wiki/Australian_Maritime_Safety_Authorityhttp://en.wikipedia.org/wiki/United_Kingdom_Maritime_and_Coastguard_Agencyhttp://www.yen.gr/http://en.wikipedia.org/wiki/Hellenic_Civil_Aviation_Authorityhttp://en.wikipedia.org/wiki/CNEShttp://www.agentschaptelecom.nl/onderwerpen/scheepvaart/Beroepsvaart/Radionoodbakens/Personal+Locator+Beaconhttp://www.406registration.com/http://en.wikipedia.org/wiki/Cockpit_voice_recorderhttp://en.wikipedia.org/wiki/Flight_data_recorderhttp://en.wikipedia.org/wiki/Underwater_locator_beaconhttp://en.wikipedia.org/wiki/Underwater_locator_beaconhttp://ecfr.gpoaccess.gov/cgi/t/text/text-idx?c=ecfr&sid=bb1f41f4b3694bd4e3089bd9bfa27d0f&rgn=div8&view=text&node=14:2.0.1.3.10.3.7.4&idno=14http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgTSO.nsf/0/e2b1e589c98200f886256dc900695b8c/$FILE/C91a.pdfhttp://en.wikipedia.org/wiki/Distress_radiobeacon#Traditional_ELT.2C_unregisteredhttp://en.wikipedia.org/wiki/Distress_radiobeacon#cite_note-24http://en.wikipedia.org/wiki/Distress_radiobeacon#cite_note-autogenerated7-21http://en.wikipedia.org/wiki/Distress_radiobeacon#cite_note-25http://en.wikipedia.org/wiki/Distress_radiobeacon#cite_note-26http://en.wikipedia.org/wiki/Distress_radiobeacon#cite_note-27http://en.wikipedia.org/wiki/Distress_radiobeacon#cite_note-28


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EPIRBs are a component of the Global Maritime Distress Safety System(GMDSS). Mostcommercial off-shore working vessels with passengers are required to carry a self-deployingEPIRB, while most in-shore and fresh-water craft are not.

As part of the United States efforts to prepare beacon users for the end of 121.5 MHz frequencyprocessing by satellites, the FCC has prohibited the use of 121.5 MHz EPIRBs as of January 1,

2007 (47 CFR 80.1051). See the United States Coast Guard (USCG)brief on the 121.5/243 Phase-out.

The most current and comprehensive information about EPIRBs is provided by the Equipped ToSurvive Foundation.

Personal locator beacons (PLBs)

Personal locator beacons operating on 406 MHz must beregistered. PLBs should not be used incases where normal emergency response exists.

Detailed type descriptions

Current types

EPIRBs (marine)

Current marine EPIRBs are generally divided into three classes; Category I, Category II, and ClassB (orCategory B). All of these units can be had for under US$600. [citation needed]

The Category I type is recommended by the IMO because a float-free bracket will deploy

automatically once the vessel sinks and the EPIRB will then be activated automatically byimmersion in water in the event of a disaster at sea. These EPIRBs are generally housed in aspecially designed bracket on deck and the buoyant beacon is designed to rise to the surfaceand emit two signals, an emergency homing signal on 121.5 MHz and a digital identificationHex Code on 406 MHz that can be used to almost-immediately alert SAR authorities of thedistress of the stricken vessel. Category IEPIRBs used in American waters must beregistered with NOAA.

Category IIEPIRBs are similar to Category IEPIRBs but are generally manual deployment

only. Also like Category IEPIRBs, Category IIunits must be registered. Class B EPIRBs, also called Category B or"Mini B", operate a 121.5 MHz homing signal

only and are usually manual deployment only units. They are the cheapest units but also theleast capable. Since the signal has no identification component, Class B EPIRBs are notregistered. Due to their limitations, Class B EPIRBs are slowly being phased out. As theInternational Cospas-Sarsat program no longer monitors Category B EPIRB signals as ofFebruary 1, 2009, this type of beacon will become fully obsolete (see above). Although theU.S. Coast Guard no longer recommends them, they remain in wide use.

ELTs (aircraft)

ELTs used in aircraft are of the following types:
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The new 406 MHz TSO-126 ELT is the only type of ELT detected by Cospas-Sarsat after

February 1, 2009 (see above).

Types Being Phased Out:

TSO-C91 121.5 / 243 MHz unregistered have not been permitted for new installations

since June 21, 1995; TSO-C91a 121.5 / 243 MHz unregistered was the replacing standard; most current

aviation ELTs are of this type.

PLBs

All PLBs must have a Hex Code on the body. Persons must register this Hex Code with theirnational SAR agency. See below for types of PLBs no longer used.

Obsolete types

Obsolete EPIRBs

There are also several older types of EPIRB devices which are no longer recommended for use.

Class A A 121.5 MHz automatic activation unit. Due to limited signal coverage and

possible lengthy delays in signal recognition, the U.S. Coast Guard no longer recommendsuse of this type.

Class C Operates on VHF channel 15/16. Designed for small crafts operating close to

shore, this type was only recognized in the United States. Use of these units was phased out

in 1999.

Class S A 121.5 MHz unit similar to Class B but is often included as an integral part of a

lifeboat orsurvival suit. Their use is no longer recommended by the U.S. Coast Guard.

Inmarsat E entered service in 1997. The unit is an automatic activation unit operating on

1646 MHz and detectable by the Inmarsat geostationary satellite system. This class ofEPIRB was approved by the Global Maritime Distress Safety System (GMDSS), but not bythe United States. In September 2004, Inmarsat announced that it was terminating its

Inmarsat EEPIRB service as of December 2006 due to a lack of interest in the maritimecommunity.

Furthermore, the U.S. Coast Guard recommend that no EPIRB of any type manufactured before1989 be used.

Obsolete ELTs

Any ELT that is not a 406 MHz ELT with a Hex Code became obsolete February 1, 2009.

Obsolete PLBs

Military forces at one time used 121.5/243.0 MHz beacons such as the "PRC-106," which

had a built-in VHF radio. These are being replaced[by whom?] by modern 406 MHz PLBs.
http://en.wikipedia.org/wiki/Distress_radiobeacon#Phase-out_of_121.5_.26_243_beaconshttp://en.wikipedia.org/wiki/Lifeboat_(shipboard)http://en.wikipedia.org/wiki/Survival_suithttp://en.wikipedia.org/wiki/Global_Maritime_Distress_Safety_Systemhttp://maritime.inmarsat.com/news/00014622.aspx?language=EN&textonly=Falsehttp://en.wikipedia.org/wiki/Wikipedia:Avoid_weasel_wordshttp://en.wikipedia.org/wiki/Wikipedia:Avoid_weasel_wordshttp://en.wikipedia.org/wiki/Wikipedia:Avoid_weasel_wordshttp://en.wikipedia.org/wiki/Distress_radiobeacon#Phase-out_of_121.5_.26_243_beaconshttp://en.wikipedia.org/wiki/Lifeboat_(shipboard)http://en.wikipedia.org/wiki/Survival_suithttp://en.wikipedia.org/wiki/Global_Maritime_Distress_Safety_Systemhttp://maritime.inmarsat.com/news/00014622.aspx?language=EN&textonly=Falsehttp://en.wikipedia.org/wiki/Wikipedia:Avoid_weasel_words


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How they work

All the systems work something like this: A beacon is activated by a crash, a sinking, or manuallyby survivors. The beacon's transmission is picked up by one or more satellites. The satellitetransmits the beacon's signal to its ground control station. The satellite's ground station processesthe signals and forwards the data, including approximate location, to a national authority. Thenational authority forwards the data to a rescuing authority. The rescuing authority uses its ownreceiving equipment to locate the beacon and makes the rescue or recovery. Once the satellite datais in, it takes less than a minute to forward the data to any signatory nation.

Overview diagram of EPIRB/COSPAS-SARSAT communication system

There are several systems in use, with beacons of varying expense, different types of satellites andvarying performance. Note that even the oldest systems provide an immense improvement in safety,compared to not having a beacon.

GPS-based, registered

The most modern 406 MHz beacons with GPS (US$ $300+ in 2010) track with a precision of 100meters in the 70% of the world closest to the equator, and send a serial number so the responsibleauthority can look up phone numbers to notify the registrator (e.g. next-of-kin) in four minutes.

The GPS system permits stationary, wide-view geosynchronous communications satellites toenhance the doppler position received bylow Earth orbitsatellites. EPIRB beacons with built-inGPS are usually called GPIRBs, for GPS Position-Indicating Radio Beacon or Global Position-Indicating Radio Beacon.

However, rescue cannot begin until a doppler track is available. The COSPAS-SARSAT

specifications say [29]that a beacon location is not considered "resolved" unless at least two dopplertracks match or a doppler track confirms an encoded (GPS) track. One or more GPS tracks are notsufficient.

High-precision registered

An intermediate technology 406 MHz beacon (now mostly obsolete in favor of GPS enabled units)has worldwide coverage, locates within 2 km (12.5 km search area), notifies kin and rescuers in 2hours maximum (46 min average), and has a serial number to look up phone numbers, etc. This cantake up to two hours because it has to use moving weather satellites to locate the beacon. To help
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locate the beacon, the beacon's frequency is controlled to 2 parts per billion, and its power is a heftyfive watts.

Both of the above types of beacons usually include an auxiliary 25 milliwatt beacon at 121.5 MHzto guide rescue aircraft.

Traditional ELT, unregistered

The oldest, cheapest (US$ 139) beacons sent an anonymous warble at 121.5 MHz. They are nolonger monitored by satellite. They could be detected by satellite over only 60% of the earth,required up to 6 hours for notification, located within 20 km (12 mi) (search area of 1200 km) andwere anonymous. Coverage was partial because the satellite had to be in view of both the beaconand a ground station at the same time the satellites did not store and forward the beacon's position.Coverage in polar and south-hemisphere areas was poor. The frequency was the standard aviationemergency frequency, and there is interference from other electronic and electrical systems, so falsealarms were common. To reduce false alarms, a beacon was confirmed by a second satellite pass,

which could easily slow confirmation of a 'case' of distress to up to about 4 hours (although in rarecircumstances the satellites could be position such that immediate detection becomes possible.)Also, the beacons couldn't be located as well because their frequency is only accurate to 50 parts

per million, and they send only 75100 milliwatts of power.

Location by Doppler (without GPS)

The Cospas-Sarsat system was made possible by Dopplerprocessing. Local unit terminals (LUTs)detecting non-geostationary satellites interpret theDopplerfrequency shift heard by LEOSAR andMEOSAR satellites as they pass over a beacon transmitting at a fixed frequency. The interpretationdetermines both bearing and range. The range and bearing are measured from the rate of change ofthe heard frequency, which varies both according to the path of the satellite in space and the rotationof the earth. This triangulates the position of the beacon. A faster change in the doppler indicatesthat the beacon is closer to the satellite's ground track. If the beacon is moving toward or away fromthe satellite track due to the Earth's rotation, it is on one side or other of the satellite's path.

If the beacon's frequency is more precise, it can be located more precisely, saving search time, somodern 406 MHz beacons are accurate to 2 parts per billion, giving a search area of only 2 squarekm, compared to the older beacons accurate to 50 parts per million that had 200 square kilometersof search area.

In order to increase the useful power, and handle multiple simultaneous beacons, modern 406 MHzbeacons transmit in bursts, and remain silent for about 50 seconds.

Russia developed the original system, and its success drove the desire to develop the improved406 MHz system. The original system was a brilliant adaptation to the low quality beacons,originally designed to aid air searches. It used just a simple, lightweight transponder on the satellite,with no digital recorders or other complexities. Ground stations listened to each satellite as long asit was above the horizon. Doppler shift was used to locate the beacon(s). Multiple beacons wereseparated when a computer program analysed the signals with a fast fourier transform. Also, twosatellite passes per beacon were used. This eliminated false alarms by using two measurements toverify the beacon's location from two different bearings. This prevented false alarms from VHF

channels that affected a single satellite. Regrettably, the second satellite pass almost doubled the
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average time before notification of the rescuing authority. However, the notification time was muchless than a day.

Operational testing

According to the U.S. Federal Aviation Administration, ground testing of type A, B and S ELTs isto be done within the first 5 minutes of each hour. Testing is restricted to 3 audio sweeps.[5] Type Iand II devices (those transmitting at 406 MHz) have a self test function and must not be activatedexcept in an actual emergency.

The United States Coast Guard web page for EPIRBs states: "You may be fined for false activationof an unregistered EPIRB. The U.S. Coast Guard routinely refers cases involving the non-distressactivation of an EPIRB (e.g., as a hoax, through gross negligence, carelessness or improper storageand handling) to the Federal Communications Commission. The FCC will prosecute cases basedupon evidence provided by the Coast Guard, and will issue warning letters or notices of apparentliability for fines up to $10,000."[15]

Satellites used

Receivers are auxiliary systems mounted on several types of satellites. This substantially reducesthe program's cost.

The weather satellites that carry the SARSAT receivers are in "ball of yarn" orbits, inclined at 99degrees. The longest period that all satellites can be out of line-of-sight of a beacon is about twohours.

The first satellite constellation was launched in the early 1970s by theSoviet Union,Canada,France and the USA.

Some geosynchronous satellites have beacon receivers. Since end of 2003 there are four suchgeostationary satellites (GEOSAR) that cover more than 80% of the surface of the earth. As with allgeosynchronous satellites, they are located above the equator. The GEOSAR satellites do not coverthe polar caps.

Since they see the Earth as a whole, they see the beacon immediately, but have no motion, and thusno doppler frequency shift to locate it. However, if the beacon transmits GPS data, thegeosynchronous satellites give nearly instantaneous response.

History
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A PLB that can use eitherGLONASS orGPS location services

Automatic SOS radios were developed as early as the 1930s.[30]

The original impetus for the program in the U.S. was the loss ofCongressmenHale Boggs (D-LA)andNick Begich (D-AK) in the Alaskan wilderness on October 16, 1972. A massive search effortfailed to locate them. The result was a U.S. law mandating that all aircraft carry an emergencylocator transmitter. Technical and organizational improvements followed.

Cospas-Sarsat is an international organization that has been a model of international cooperation,even during the Cold War. SARSAT means Search And Rescue Satellite Aided Tracking. COSPAS() is an acronym for the Russian words "Cosmicheskaya Sistema Poiska AvariynyhSudov" ( ), which translates to "Space Systemfor the Search of Vessels in Distress". A consortium of Russia, the U.S., Canada and France formedthe organization in 1982. Since then 29 others have joined.

Cospas-Sarsat defines standards for beacons, auxiliary equipment to be mounted on conformingweather and communication satellites, ground stations, and communications methods. The satellitescommunicate the beacon data to their ground stations, which forward it to main control centers ofeach nation that can initiate a rescue effort.

The U.S. Coast Guard once promoted an emergency beacon onmaritime VHF emergency channels.It now promotes the superior Cospas-Sarsat system, and no longer services emergency beacons on

maritime VHF frequencies.

Current events

In a Safety Recommendation released September 2007, the U.S.National Transportation SafetyBoard once again recommended that the U.S. FAA require all aircraft have 406 MHz ELTs. [31] Theyfirst recommended this back in 2000 and after vigorous opposition by AOPA, the FAA declined todo so. This recommendation is apparently a reaction to the cessation of 121.5 MHz satellite

processing. Citing two recent accidents, one with a 121.5 MHz ELT and one with a 406 MHz ELT,the NTSB concludes that switching all ELTs to 406 MHz is a necessary goal to work towards. [32]
http://en.wikipedia.org/wiki/GLONASShttp://en.wikipedia.org/wiki/GPShttp://en.wikipedia.org/wiki/Distress_radiobeacon#cite_note-30http://en.wikipedia.org/wiki/Distress_radiobeacon#cite_note-30http://en.wikipedia.org/wiki/United_States_House_of_Representativeshttp://en.wikipedia.org/wiki/Hale_Boggshttp://en.wikipedia.org/wiki/Hale_Boggshttp://en.wikipedia.org/wiki/Nick_Begichhttp://en.wikipedia.org/wiki/Alaskahttp://en.wikipedia.org/wiki/Cospas-Sarsathttp://en.wikipedia.org/wiki/Cold_Warhttp://en.wikipedia.org/wiki/Acronym_and_initialismhttp://en.wikipedia.org/wiki/Marine_VHF_radiohttp://en.wikipedia.org/wiki/Marine_VHF_radiohttp://en.wikipedia.org/wiki/National_Transportation_Safety_Boardhttp://en.wikipedia.org/wiki/National_Transportation_Safety_Boardhttp://en.wikipedia.org/wiki/Distress_radiobeacon#cite_note-autogenerated4-31http://en.wikipedia.org/wiki/Aircraft_Owners_and_Pilots_Associationhttp://en.wikipedia.org/wiki/Distress_radiobeacon#cite_note-32http://en.wikipedia.org/wiki/File:GLONASS_GPS_Personal_Radio_Beacon.jpghttp://en.wikipedia.org/wiki/File:GLONASS_GPS_Personal_Radio_Beacon.jpghttp://en.wikipedia.org/wiki/GLONASShttp://en.wikipedia.org/wiki/GPShttp://en.wikipedia.org/wiki/Distress_radiobeacon#cite_note-30http://en.wikipedia.org/wiki/United_States_House_of_Representativeshttp://en.wikipedia.org/wiki/Hale_Boggshttp://en.wikipedia.org/wiki/Nick_Begichhttp://en.wikipedia.org/wiki/Alaskahttp://en.wikipedia.org/wiki/Cospas-Sarsathttp://en.wikipedia.org/wiki/Cold_Warhttp://en.wikipedia.org/wiki/Acronym_and_initialismhttp://en.wikipedia.org/wiki/Marine_VHF_radiohttp://en.wikipedia.org/wiki/National_Transportation_Safety_Boardhttp://en.wikipedia.org/wiki/National_Transportation_Safety_Boardhttp://en.wikipedia.org/wiki/Distress_radiobeacon#cite_note-autogenerated4-31http://en.wikipedia.org/wiki/Aircraft_Owners_and_Pilots_Associationhttp://en.wikipedia.org/wiki/Distress_radiobeacon#cite_note-32


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Alternative technologies

There are also other personal devices in the marketplace which do not meet the standard for406 MHz devices.

GPS aircraft tracking

Active aircraft tracking

There are several active aircraft tracking systems available on the market that use the "bread-crumbapproach" to SAR. Rather than relying on an emergency locator transmitter to transmit uponimpact, the next generation of emergency locating devices are active tracking devices that send

position reports at regular time intervals. If the unit stops transmitting upon impact, the historicaltransmissions will give the last known location of the aircraft, its speed, direction and altitude.Tracking as an alternative or complement to current technology has recently been encouraged bythe Coroner in New Zealand.[33]

SPOT

SPOT does not use the 406 MHz signal nor the system of satellites. Instead, it depends on theGlobalStarsatellite system. It has richer features (for instance, can send many non-emergencysignals) but it does not work in as many places as 406 MHz PLBs for instance under denseforest canopy or steep canyons.[34]When a user presses the "911" button on a SPOT device anemergency message containing the unit's identification and GPS location is transmitted to theGEOS International Emergency Response Center who then notifies the appropriate emergencyagency for the region after first calling the user to ensure the transmission is not accidental. [35][36]

SPOT additionally has the ability to provide non-emergency web based tracking information. Thisallows family or friends at home to track the holder's progress. The tracking operates by sending atracking signal to the GlobalStarnetwork every 10 minutes. This feature can additionally be usefulto provide location of an individual even if the individual is unable to activate the emergency '911'

button.[37]

Typical costs are $169 plus a $99/year service fee for basic services or $150/yr for basic servicesand tracking services, as compared to around $250 for a 406-MHz PLB with no service fee.

Spidertracks

Spidertracks is also completely independent of the 406 MHz system... a unit in the aircraftperiodically transmits its position via the Iridium satellite constellation. The position is recorded. Ifno position report is received when it is expected, a call is made to the owner's cellphone. If noresponse is received, SAR are called with the last recorded position. The aircraft's position is alsoavailable via a website.[38]

inReach

inReach, like SPOT does not use the 406 MHz signal nor the system of satellites. Instead, itdepends on the Iridium satellite system. Unlike SPOT inReach is a two way system capable of

receiving confirmation that the message was received. Like SPOT the message is transmitted to the
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private GEOS International Emergency Response Center who then notifies the appropriate SARauthorities.

inReach also provides tracking capability and two way SMS type text messaging allowing familyand friends to track and send and receive updates from the trail. Pricing starts at USD$9.95/mo withall messages pay as you go to USD$44.95 per month for unlimited tracking [39] and a message

bundle.

TracMe

TracMe [40]simply beacons an automated message on a short-range FRS or UHF CB frequency. Itdoes not notify authorities that you are missing. TracMe's website recommends you arrange forrescue by notifying a friend about your plans, and ask them to call authorities and inform them of

your general whereabouts and that you have a TracMe if you are late returning.[41]Then, the search-and-rescue team will need to radio-triangulate on the signal. [42]

TracMe has had a dispute with the FCC whether the device can be called a "Personal Locator

Beacon".[43]

The company lists it at a cost of $49.95 and it allows a single use. The company also promises afree replacement if it's used for a genuine emergency.

APRS

Automatic Packet Reporting System is used by amateur radio operators to track positions and sendshort messages. Most APRS packets contain a GPSlatitude and longitude, so they can be used for

both normal and emergency tracking. They also are routed to the Internet, where they are archived

for some period of time, and viewable by others. There are several emergency packet types that canindicate distress. Since it is part of the amateur radio service, it costs nothing to transmit on and usesthe extensive network, however, one must be a licensed amateur radio operator. There is also noguarantee that an APRS distress packet report would be seen or handled by emergency responders.It would have to be seen by an amateur radio operator and forwarded on.
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