With Christmas rapidly approaching and many people thinking about buying presents to help keep their loved ones safe when they’re outdoors, we thought we’d take the time to explain the difference between PLBs vs. SEND Devices and how the two work.

Personal Locator Beacons (PLB’s)
A 406-MHz beacon designed for individual use is known as a Personal Locator Beacon or (PLB).

The International COSPAS-SARSAT Programme, which is an intergovernmental cooperative of 43 countries and agencies, maintains a network of satellites and ground facilities to receive distress signals from 406-MHz beacons and route these alerts to the authorities in more than 200 countries and territories. Here in New Zealand and around the South Pacific basin, these distress signals are monitored by Rescue Coordination Centre New Zealand (RCCNZ), which is part of Maritime NZ 

The positions are derived by both the satellite trilateration and the devices internal GPS which are sent with the PLB’s unique identifying number (UIN) to the relevant RCC. This UIN is what links the PLB to the owner when the PLB is registered.

The key benefit that PLB’s provide is that they produce a signal on 406-MHz and 121.5-Mhz called a homing signal. Rescue services and overflying aircraft can detect this homing signal to help direct them to the exact location of those in distress. This can be crucial if there is position error from the device, the device has a limited view of the sky due to terrain shielding – common (for any device that uses satellites) in a steep narrow valley with high mountains, those in distress are hard to see due to forest canopy, camouflaged, lighting or the visibility is poor.

It’s key to register your PLB which is free as this helps provide rescue services key information so the most appropriate response can be achieved. Part of this is having nominated and contactable emergency contacts who know what your intentions are, can provide key information like: How many in the groups, their ages, activity, route, medical conditions, level of experience and equipment they may have with them. If a PLB is accidentally activated, this can be a quick way to contact the owner before sending rescue services which takes them away from others that may need them. This is a legal requirement, but importantly creates a key linkage to help you if you are in distress. Buying a NZ coded PLB means that if you activate your PLB overseas, RCCNZ will also receive your alert and can work with foreign RCC’s to assist with your distress if it’s registered.

406 MHz is the radio-frequency band that distress beacons transmit at and it’s the band monitored around the Earth by COSPAS-SARSAT. A COSPAS-SARSAT beacon, also called a distress beacon or (emergency beacon). These are radio transmitters that when activated when the user is in grave and imminent danger (a life-threatening situation), help summon assistance from the emergency services.

Satellite Emergency Notification Device or SEND
These are portable emergency notification and locating devices which use commercial satellite systems rather than the COSPAS-SARSAT satellite system. Two main examples of these are Garmin inReach or SPOT devices.

These devices use an internal GPS chip to gather location information. When the SEND is triggered, information is sent via commercial satellite to a commercial monitoring agency whose role it is to pass on the information to an appropriate agency which is RCCNZ in New Zealand who then coordinate the response.

The International Emergency Response Coordination Centre (IERCC) maintains an accurate and up-to-date database of response agencies to contact and can quickly determine which is appropriate to the situation/location. The commercial, IERCC is GEOS, used by both Garmin and SPOT SENDs.

Garmin inReach

Like SPOT, inReach devices do not use the 406 MHz signal nor the system of SAR satellites. Instead, they depend 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 private GEOS International Emergency Response Centre who then notifies the appropriate SAR authorities.

With inReach, the device also provides tracking capability and two-way SMS text messages, with additional features increasingly being offered: sending preprogramed messages, breadcrumb tracking via Google Earth. Some newer devices offer two-way communication via satellite. With an active satellite subscription, you can stay in touch globally. You can send and receive messages, navigate your route, track, and share your journey and, if necessary, trigger an SOS to a 24/7 staffed global emergency response coordination centre via the 100% global Iridium® satellite network.


At the end of the day, whether buying a PLB or a SEND device, make sure you and your loved ones are carrying either or both and give them a real lifesaving gift this Christmas.