A Personal Locator Beacon (PLB) is a small emergency device used in a situation that the group has deemed life-threatening. This could include pre-existing medical issues such as a condition or diabetes that flare up, or severe injuries like head injuries or snake bite. It is lightweight, small and practical, suitable for bushwalkers to carry on their person.

Most PLBs contain a Global Positioning System (GPS) to report the location, making it easier and faster for emergency services to respond appropriately.

When activated, a PLB transmits a distress signal which is detected world-wide by the global satellite system, Cospas-Sarsat, and is then relayed to the appropriate emergency services. The emergency services then dispatch a rescue team to the coordinates the beacon transmitted. Exactly how the response team is dispatched, and how quickly is can reach the party, depends on the terrain and weather conditions. Helicopters, for instance, can only operate under clear weather conditions. Sometimes a response party is sent in by foot, which means the response times vary and you still need to be prepared to wait.

As well as transmitting the PLB’s ID and location via satellite the PLB also transmits a homing signal for the search and rescue team. This can make it easier to find the PLB in dense vegetation and around cliffs.

PLBs are a single use device and the battery must be replaced after it has been activated.

PLB’s are part of a larger family of devices called ‘Distress Beacons’. They are heavily regulated devices and are required to meet very strict requirements. Sometimes you hear the names for different devices used incorrectly.

EPIRBs (Emergency Position Indicating Radio Beacons) are used in ships and boats, and are designed to float upright in using the water plane as a reflector to more efficiently get the signal to the satellite. EPIRBs are required to adhere to State and Territory Marine regulations, and their required size and weight make them impractical to be used for bushwalking.
Note: A PLB is not a substitute for a Marine EPIRB.

ELT (Emergency Locator Transmitters) are designed for aviation use. They are fixed units in aircraft and automatically activated when an aircraft crashes. Again they are too large and heavy for bushwalkers.

EPIRBs and ELTs are designed to stay with your vehicle (car, boat or aircraft). You may, as an additional safety measure, choose to carry a PLB, in the event where you become separated from your vehicle.

Understanding how a PLB works will help you think through where and when to activate the device.

All distress beacons (PLBs, EPIRBs and ELTs) send signals on dedicated world-wide frequencies. The signals are received by the COSPAS SARSAT satellites, the international satellite system for search and rescue (SAR).

Image courtesy of http://beacons.amsa.gov.au/about/how-they-work.asp

Using the sequence in the diagram above:

1. A distress signal is transmitted from a PLB/EPIRB/ELT.
2. The signal is received by the COSPAS SARSAT satellites.
3. The satellites send the signal to the nearest receiving stations on earth known as Local User Terminals (LUTs).
4. A Local User Terminal forwards the message to a Mission Control Centre (MCC).
5. When a signal is received and identified to be a distress call from Australia the Rescue Coordination Centre (RCC) in Canberra is alerted.

The appropriate emergency service for the distress call is then activated. In the case of bushwalkers this is a land rescue and therefore the Police is the responsible authority. The Police would activate emergency services as required to locate and rescue the walker in distress – usually a rescue helicopter.

In the Australian search and rescue region there are three LUTs located at Albany (WA), Bundaberg (QLD) and Wellington (NZ) that are controlled by the MCC located within the Australian Joint Rescue Coordination Centre (JRCC) in Canberra.

For a video presentation of the rescue process please check out this youtube video by ACR Artex.

(Information adapted from http://www.sarsat.noaa.gov/faq%202.html)

A satellite in a geostationary orbit is at an altitude of 22,300 miles (35,890 kilometers). The satellite moves in a circular orbit in the equatorial plane around the Earth at the same speed that the Earth rotates. Because of this, it appears to remain over a fixed point on the Earth’s surface. This position is ideal for making uninterrupted observations of the weather or environmental conditions in a given area. This same principle allows it to monitor for 406 MHz distress beacons. However, satellites in geostationary orbit cannot see the polar regions of the world.

A low earth/polar orbit allow the satellites to observe the entire Earth’s surface as it rotates beneath it. Most of these orbits are at an altitude of 500 miles (800 km) and take about 100 minutes to revolve around the earth. The sun-synchronous orbit is a special case of a polar orbit with inclination of 98.7 degrees, that precesses at exactly the required rate (~ 1 degree per day) to remain in the same local time plane as the Earth rotates around the sun. Satellites in polar orbit provide emergency beacon users with global coverage (including the Polar Regions).

There are three ways that a PLB can be located by authorities:

1. By the device transmitting the GPS location.
2. Satellites calculating location using Doppler effect.
3. The use of the homing signal by aircraft or ground crew.

If a 406 MHz emergency beacon is equipped with a Global Position System (GPS) receiver, the digital message transmitted by the beacon can contain the GPS-generated position of the beacon. This is a common feature of modern PLB devices. Once the signal has been picked up by satellites, emergency services can dispatch to the exact location quickly.

In the absence of GPS coordinates being transmitted, Low Earth Orbiting Search and Rescue (LEOSAR) satellites can compute a location for a 406 MHz emergency beacon using a method called “Doppler shift”. When the beacon is moving toward or away from the satellite track due to the Earth’s rotation, the frequency shift induced by that motion can be used to compute location. Computing a location using Doppler shift requires the satellite to be moving, that is, the satellite cannot be in a geostationary orbit (GEOSAR).

Because their geostationary orbit does not provide a relative motion between a distress beacon and a GEOSAR satellite, there is no opportunity to use the Doppler effect to calculate the location of a beacon. Therefore, the GEOSAR satellites only can relay a beacon’s distress message. The LEOSAR satellites also provide global coverage, including the Polar Regions, for 406 MHz emergency beacon detection.

Many 406 MHz emergency beacon are also equipped with a 121.5 MHz ‘homing’ frequency, what aircraft overhead can use to locate the device. This is a separate signal to the 406 MHz distress signal, and can also be used by land crew to locate the device.

Prepare for a long wait….

The time it takes for search and rescue personnel to reach you depends on a number of factors, including the weather, terrain and accessibility of your location. The more remote the location of the distress incident, the longer the response time. Whether your PLB is registered and GPS equipped also play a very important role.

Do stay with the PLB as this is the location that the emergency services will use to locate the casualty. Wandering off attempting to find your way home will only delay rescue.

Don’t turn off the PLB, even if you no longer need rescuing. If the signal fails, the rescue team may assume your PLB battery has expired and commence a blind search. If you triggered the PLB by mistake or no longer need assistance do your best to contact emergency service and let them know what happened, they will direct you to switch it off.

Do leave the PLB on until directed to turn off by the emergency services. If you have not been located yet then leave it on until the battery goes flat.

In a group
If you are in a group, do not activate more than one beacon at a time. When the first beacon’s battery goes flat then turn it off and activate the second one. You will not get a stronger signal by activating two beacons at the same time – the transmissions actually interfere with one another and make it harder to find you. The battery life of a PLB is more than 24 hours, it is unlikely that rescue will take that long to arrive.

It’s important to remember that a PLB is a last resort, only to be turned on in life-threatening situations and when no other direct communication is available. Wherever possible, your emergency call should still be made by telephone, which allows two-way communications and results in a faster and more appropriate response.

What amounts to a life-threatening emergency
When you feel that you are in a situation of grave and imminent danger. Some examples of life threatening situations are if someone is:

• Suspected of having a heart attack
• Unconscious
• Having a severe asthma attack and not responding to medication
• Hurt badly from a fall
• Acting irrationally after a blow to the head and you suspect a brain injury
• Burned badly from a fuel stove explosion
• Bitten by a snake
• Lost and unable to recover
• Caught in a bushfire
• Serious injury were delay in self rescue may cause longterm impairment (eg stick in eye or broken leg)

It does not take a lot for a relatively minor injury or illness to become life threatening if the group attempts to self-evacuate. Consider the injury and whether it is life threatening in the context of the environment you are in. Someone who is potentially having a heart attack needs medical aid urgently. Even with good first aid, someone with a broken leg may go into shock or tear a blood vessel.

There is no need to try to be a hero if it puts other people’s lives at risk. If you have a genuine concern for someone’s welfare, and it is reasonable to think their life or serious injury is at stake then activate the PLB. If you feel that time is on your side then consider options such as splitting the party to send a message, but this also introduces risks, so take care.

When not to activate the PLB
The emergency services provided in Australia are amazing. When a PLB is activated the emergency services have very little information and assume the need is urgent and life threatening. Responding to a PLB may take resources away from other cases that are assumed to be less urgent.

In general, the following scenarios can be dealt with without activating a PLB:

• If you are simply overdue from a walk.
• Minor injuries or illness.
• Running late for an aeroplane flight (yes it has happened, don’t do it yourself).

IF YOU ARE UNSURE, ERR ON THE SIDE OF CAUTION.

Accidental activation
If your beacon has been activated accidentally then turn it off and phone the Australian Maritime Safety Authority (AMSA)1800 641 792 as quickly as possible to let them know that it was a false activation. There is no penalty for accidental activation.

PLB sends a message using satellites orbiting the Earth, you will get the best result if you are in an open area with a clear view of the sky. Best to be clear of dense tree canopy, buildings, mountains, and vehicles. The aerial must be vertical pointing towards the sky, preferably with 180 degrees or more of visibility. Always follow the instructions on the PLB.

PLBs do not work in caves and deep narrow gorges
They will be slow to signal an emergency in narrow canyons and gorges with a limited view of the sky and not work at all in places such as caves. As much as possible, position the PLB where it can ‘see’ as much of the sky as possible.

Detection of distress signals can also be affected by bad weather such as lightning and strong wind, and rescue operation delayed due to poor visibility at night. So if you are in a narrow gorge such as a Blue Mountains canyon at night in bad weather, you may well have to wait a long time for the rescue crew to reach you, even if your signal is detected. In such situations, if you are in a group, it may be more effective to send somebody out to raise the alarm as well.

Using a PLB anywhere near water
If using a PLB near water (including river crossings) it is highly recommended that you purchase one that floats (either self buoyant or aided by external flotation pouch) and is fully waterproof. PLBs sold in Australian and New Zealand must meet AS/NZS 4280.2.2003, which requires that the PLB must be waterproof and capable of floating.

If purchasing a waterproof PLB, check that it has a waterproof aerial as some PLBs, while waterproof, don’t have a waterproof aerial and do not work as effectively when activated in the water.

It’s worth spending a bit of time figuring out what features are important for a PLB unit. There are a great range of models on the market and nowadays are relatively affordable and last a long time. Read on for some more advice on where to purchase and features to look out for.

PLBs can be purchased from marine suppliers, aircraft re-fitters, bushwalking and camping supply stores. The cost varies (between $300 to $500 current as at Jan 2017) according to performance and specifications.

PLBs are subscription-free devices, so have no cost of ownership after the initial purchase.

Be aware that some overseas beacons are not compatible with the Australian system. The safest way to avoid this problem is to purchase your PLB from a reputable Australian retailer.
Australian Maritime Safety Authority (AMSA) provides a list of PLB distress beacon models that, if purchased in Australia, are known to meet Australian Standards AS/NZS 4280.1 and AS/NZS 4280.2, as well as a guide on choosing the right beacon, for details click here.

PLBs are available on loan at a nominal cost or for free from the National Parks and Wildlife Services (NPWS). For Sydneysiders, try the Blue Mountains Heritage Centre at Blackheath, and after hours at the Katoomba and Springwood Police Stations.

At the NPA, our regular leaders have long term loan units which they carry with them on all club trips. Our Sydney Branch office has an additional supply of units that members can borrow by contacting the activities coordinator ([email protected]).

PLBs come in two basic types – those which provide an encoded (GPS) location and those which do not.

A GPS equipped PLB allows the beacon to acquire current location coordinates from an internal GPS receiver, sending an even more precise location of the beacon to the satellites, i.e., latitude and longitude data. This helps Search and Rescue Authorities (SAR) to reach the location even faster.

AMSA recommends beacons with Global Positioning System (GPS), which helps the rescue team to locate the distressed bushwalker. If your beacon is registered and activated correctly:

• With a non-GPS beacon, your position could take anywhere between 90 minutes to 5 hours to locate with precision < 5 kilometres.
• With a GPS beacon, you could be located within 20 minutes with precision < 120 metres.

⚠ After 1 Feb 2010, old analogue EPIRBs and PLBs operating on 121.5 MHz are no longer licensed for use. You must carry a digital 406 MHz distress beacon.

The Old – 121.5MHz/243 MHz Analog Distress Beacon System
Analog transmission beacons have been replaced by the digital system are no longer supported. Analog devices should not be used any more, and must be disposed of immediately.

The 121.5/243 MHz system was a simple analog system. Cospas-Sarsat ceased satellite detection and processing of 121.5/243 MHz beacons in 2009. These older beacons are now only detectable by ground-based receivers and aircraft. This means a beacon activated on this system requires a land receiver, aircraft or ship to be close enough to receive the signal; then the pilot/captain needs to be monitoring the channel, detect the signal, perform direction finding procedures and report it to authorities. This is patchy and random at best so is therefore totally unsuitable for an emergency system.

The major problem with this system was that it had an overwhelming number of PLB false alarms – AMSA indicates about 97% of activations were false alarms.
However, when an PLB is detected there is no way of knowing whether it is a genuine
emergency or not so they must assume it is genuine and send in resources to track it down.
This makes it a very inefficient and expensive system. This problem is one of the major
reasons the satellite tracking of 121.5MHz was ceased in February 2009.

All beacons on this old system should be disposed of appropriately.

The New – 406MHz Digital Distress Beacon System
The 406MHz system is digital and therefore allows more information to be sent when a beacon is activated.

Image courtesy of https://transmoto.com.au/product-kti-personal-locator-beacon/

Each 406 MHz distress beacon has a HexID or Unique Identification Number (UIN) programmed into it

The HexID can be found on the label of all 406 MHz distress beacons.

This HexID must be provided when registering your PLB, and is the only code that links the distress beacon to the registered owner. This means you should register your 406MHz PLB with AMSA straight away!

The advantages of this identifying signal are:

• Authorities know straight away whether the signal is received from a boat, aircraft or a bushwalker and can deploy resources appropriate to the incident more quickly.
• Many false alarms can be eliminated easily as the received signal’s identification can be referenced to the registered owner of the beacon. The owner can then be contacted and the details of the incident established quickly.
• It has a stronger signal strength so is more likely to be received from marginal areas
  such as gorges and under a tree canopy.

Other advantages of the new 406MHz system include:

• The 406MHz system provides alerts far more quickly with alerts being received within minutes from the satellites in geo-stationary¹ orbit over the Equator.
• The 406MHz beacons are located fixed by the polar orbiting² satellites to within 5km. These low earth orbit satellites also detect PLB’s in many areas that are hidden from geostationary satellites or hard to get an accurate reading from. Hence, using low earth orbit satellites means that rescuers are closer to the party that needs rescuing before they need to start direction finding.
• The 406MHz digital beacons also have a secondary distress transmitter on 121.5MHz and is used for “homing” purposes. When the rescue services get close, this allows them to easily locate the beacon by using radio direction finding techniques.

Note 1. Geo-stationary Satellites: satellites that circles the Earth in a geosynchronous orbit, which means they orbit the equatorial plane of the Earth at a speed matching the Earth’s rotation. This allows them to hover continuously over one position on the surface.

Note 2. Polar-orbiting satellites: satellites that is constantly circling the Earth in an almost north-south orbit, passing close to both poles.

If you’re thinking about purchasing a PLB for bushwalking, there are a few features to watch out for. Most modern PLBs are built to certain standards but it is worth double checking that the unit is appropriate for the activities you plan to do.

1. GPS equipped
   Most modern PLBs are GPS equipped, but it’s important to double check as a more accurate transmission of your location will speed up rescue significantly.
2. Transmission time minimum 24 hours once activated
   Once activated, most models of PLB will transmit continuously for a minimum of 24 hours. This is important if the rescue team cannot despatch a crew immediately, or weather conditions cause delays.
3. Waterproof and self-buoyant or external flotation
   PLBs are generally watertight for a period of time but the duration depends on depth and temperature of the water, and the model of the PLB. Not all PLBs float – a problem if used in settings where there is deep water and potential to drop or lose the device (e.g. wet canyons)
4. Appropriate battery life
   PLBs run on a battery that has a finite life (between 5 to 10 years) and should be replaced before the battery expires to ensure that the unit will still work in an emergency.
5. Weight
   PLBs are getting increasingly lighter and smaller with every new model. Consider spending a little more to get a super lightweight, small model that can easily be carried.
6. Appropriate temperature range
   Check the operating temperature range and make sure that it is appropriate for where you plan to use the device.

Example Image of a PLB, the SA2G model made by Kinetic Technology International. Battery life lasts 10 years, 24 hour transmission time minimum, GPS equipped and waterproof. See http://kti.com.au/. NPA purchased a number of these units to replace its fleet in 2016. So far, we have been impressed with this model for it’s size, battery life and costs.

AMSA now requires all PLBs to be registered.

A registered PLB allows the search and rescue authorities to phone your emergency contacts and look up important information to initiate a response as soon as possible. An unregistered beacon slows down this process, which might result in a delayed response.

You can register online (preferred method), or alternatively you can download, print and complete this form: https://www.amsa.gov.au/forms-and-publications/amsa6.pdf.

To register online you need to:

1. Visit https://www.beacons.amsa.gov.au/
2. Select ‘register a beacon’.



3. Then follow the prompts and enter the information as required. You will need:
   1. The ‘Hex ID’, which is normally located on the side of the beacon and will contain 15 characters consisting of the letters A-F and numbers 0-9.
   2. Your name, and contact details.
   3. Three emergency contacts. These are the people that emergency services will contact to make sure that the PLB has not been accidentally set off, and can provide a bit more information. Make sure you choose people that are likely to have phone reception, usually respond quickly to phone calls, and know details of your trip. Also, choose people that keep a cool head in an emergency.
4. You can also enter a bit of general information about the PLB. We recommend you enter a statement similar to this, but modify the details to suit your walking habits: “This PLB is used by {your name}. Walks are typically done in the [insert name] region. Walks involve on-track, off-track walking, overnight trips, and canyoning”.
5. You can also enter specific trip intentions for individual trips. We recommend you do this for your activities out of mobile coverage, especially overnight trips, and trips with significant off-track sections.

Storing the PLB in your first aid means that it automatically comes with you when you packs your first aid kit, and is quick to find in an emergency. Before starting the trip, remind everyone in the group where the PLB is stored, and run through how the PLB is triggered in an emergency.

If travelling solo, make sure that the PLB is somewhere easy to reach, near the top of your pack. If you take your pack off to explore a side gully, collect water, or check out a campsite, carry the PLB on your person. Some PLBs have arm bands so you can attach the beacon to your body for easy access.

Unfortunately, the circumstances where you will have to trigger a PLB will usually be quite stressful. It’s a good idea to familiarise yourself with your PLB beforehand.

After you have purchased or hired your PLB, unpack the PLB and familiarise yourself with the unit. Get to know how to activate it, and when to use it. Careful not to break the seal or actually activate the unit when getting familiar with it. It is a single use device and needs to be replaced after it has been activated.

While we do not endorse any particular brand of PLBs, here are a selection of popular models:

• KTI safety Alert SA2G
• ACR ResQlink+GPS
• McMurdo Fast Find 220
• Ocean Signal RescueMe PLB1
• Kannad Safelink Solo PLB

Like any electronic equipment, it’s important to look after and maintain your PLB for optimum performance. This includes keeping the unit registered with accurate information on the owner and their emergency contacts, and regularly testing the unit to make sure it is working ok.

Registration
Updating and renewing your PLB registration is free and can be done online through the AMSA registration system. Make sure to update your registration with any changes of personal details and emergency contracts as soon as possible. AMSA requires you to renew your PLB registration every two years.

Storage
PLBs should be stored:

• In the hard pouch provided, in a cool, dry place (also refer to the manufacturer’s user manual for instructions);
• Away from heat, high pressure water sprays, magnetic sources such as large speakers; and
• Away from children who may think it is a toy.

Testing

• Each PLB comes with a test button, and should be tested according to the manufacturer’s instructions and guidelines.
• The PLB should have enough excess battery life to perform a certain number of tests over the life of the battery.
• Do not overtest which can drain the battery.

Battery replacement
PLB batteries have a finite life between 5 to 10 years (depending on model), and should be replaced by an authorised servicing agent (see Servicing):

• Prior to expiry date; and
• After emergency use.

When and where to service PLBs?
Your PLB needs to be serviced and battery replaced after emergency use. The battery will have depleted and other parts such as the water seal and electrical properties need to be tested.

Only the manufacturer who is identified on the side of the PLB is certified to service your beacon.

If the beacon battery was replaced or serviced by a non-certified service centre then the beacon is non-compliant for carriage requirements and there is a risk the beacon may not function correctly.

Disposal of old PLBs
Do not throw your PLBs in a garbage bin. PLBs can still be inadvertently activated in the rubbish and in tips. PLB batteries contain hazardous materials and post harm to the environment if not disposed of properly.

Every year valuable rescue resources are spent in tracing false alarms sent off by incorrectly disposed beacons, and hence drawn away from real emergencies.

The old system PLBs (121.5MHz/243 MHz Analog Distress Beacon System), and any unwanted PLBs should be disposed of correctly by either:

• Contacting your local battery store such as Battery World to check whether they disconnect and dispose of beacons. A small fee may apply.
• Contact your local maritime safety agency. They may be able to provide disposal advice.
• Check the beacon manufacturer’s instructions, they may provide instructions on how to disconnect the beacon battery. Once disconnected, contact your local waste management facility to ask about disposing of your unwanted beacon in an environmentally friendly way. A small fee may apply.

After disposing of your unwanted beacon please advise the Australian Maritime Safety Authority (AMSA) by updating your online registration account or by phoning 1800 406 406.

So far, we’ve covered PLBs in detail, as they are considered an easy and reliable way of contacting emergency services. Basically, if emergency services receive a PLB signal, they will respond as if the signal is life-threatening.

In recent years, however, other technologies have emerged that allow you to communicate a signal to your family or emergency contact saying additional things like you’re ok or delayed. Some of these devices offer one-way communication only, while others work like a mobile phone offering two-way communications. This means that people back home can track where you are going or follow a change of route.

While more information is often a good thing, it’s important that trip intentions and the exact meaning of each message are clearly communicated to your emergency contacts before heading out to avoid confusion. For instance, have clear plan for what to do if a pre-programmed message is not received, or what a Help request means.

Be sure to understand the differences between a SPOT and other trackers and a PLB before purchase and use.

SPOT trackers are not PLBs. The main differences between the two systems are:

• SPOT trackers are covered by the same stringent regulations as PLB, so it’s much easier to end up with a model that does not have the appropriate regulations around battery longevity, transmission consistency, and how to deal with an emergency signal.
• The satellite network that SPOT trackers use is not purpose built for emergency response, hence there could be delays in recognising and processing an emergency call for help in a timely manner.
• SPOT trackers have a variety of functions, including being able to communicate signals like “I’m fine” to nominated recipients. With all these additional functions, it’s possible that the battery could run flat, leaving nothing to call for help in an emergency.
• SPOT trackers do not have a secondary distress transmitter. Most PLBs transmit an additional 121.5MHz signal that can be used by aerial or ground response teams to “home in” on the signal.
• SPOT trackers require monthly registrations, so if the user forgets or is unable to do their monthly renewal, the device won’t work.

Having said this, SPOT trackers do have the advantage over PLBs that they are able to send more detailed information. Two-way communication allows for better information sharing with rescue authorities. For example, it’s possible to send a message telling your contacts that you are fine, just delayed.

To sum up, if it’s possible, then the ideal solution is to carry both a PLB and SPOT tracker amongst the group. However, if that’s not possible or cost-prohibitive, a PLB provides the most robust method of calling for help in an emergency and in most cases is the better choice.