Foley: Calling for help: Satellite Messengers and PLBs |

Foley: Calling for help: Satellite Messengers and PLBs

Greg Foley
Mountain Rescue
PLBs send a signal to a satellite system, then the message is routed to Search and rescue authorities.
Image courtesy of Greg Foley |

Satellite messengers and personal locater beacons (PLBs) are two different types of electronic devices that allow you to call for help from pretty much anywhere on the planet you might be exploring. They all work by sending an emergency message to an array of stationary or orbiting satellites that is then routed to the appropriate rescue authorities.

They have an advantage over cell phones in that they work even when there is no cell service. That said, if you are able to call 911 with your phone, notification will be significantly quicker.

One more disclaimer. No electronic device should be your primary backcountry safety plan. Electronics cannot provide warmth, shelter, water or food.

How it works

A PLB sends an emergency signal when activated to the Cospas-Sarsat international search and rescue satellite system which is monitored worldwide. In the United States, the Air Force Rescue and Recovery Center (AFRCC) in Florida is responsible for notifying SAR authorities. The Cospas-Sarsat system basically uses triangulation from different satellites to determine the location of the device. Until the system is able to “home in” on the PLB the location may be only accurate within a mile or two, but with more satellite overpasses accuracy is much improved. PLBs also send out a homing signal on a separate frequency that SAR can use to locate you. Most new PLBs are capable of sending a GPS location message as well which pinpoints the user location within 50 feet.

PLBs have excellent worldwide coverage and cost $200-300 for a basic model. PLBs put out a much stronger signal than satellite messengers and so may work better when there is not a clear view of the sky due to tree cover or topography. Another advantage of a PLB over a satellite messenger is that there is no recurring subscription fee. It is extremely important, and required by law, to register your PLB so that search and rescue agencies have contact information for the owner and any emergency contacts.

Satellite messengers use commercial satellite arrays to send the emergency request to a private communication center. The message includes a GPS location if the unit has a good view of the sky. Various models of satellite messengers have other capabilities that may be useful including the ability to function as a GPS, send non-emergency location information to family or friends or send and receive text messages via satellite. Of course there is a cost for this functionality. Besides the purchase price, annual or monthly subscription fees are required and vary depending on the options selected.

There are two brands of messengers that dominate the market – DeLorme and SPOT.

The SPOT Gen3 satellite messenger costs $170 and the baseline subscription fee is $150 per year. Besides sending an emergency message to authorities you can send location and tracking information to friends and family vie text and email. They can go to the SPOT website and see the location on a map. Upgrades are available that enhance the tracking feature and provide a roadside assistance service. SPOT uses the Globalstar satellites which do not provide good coverage in polar regions and some mid-ocean and African locations. Check out their coverage map if you are going to be travelling to exotic locations outside the US.

DeLorme offers messengers with basic location and tracking services like the SPOT, plus the ability to send and receive texts via satellite and GPS features. They claim 100 percent coverage anywhere on earth with the Iridium satellite network.

The DeLorme inReach SE costs $300 with subscription fees starting at $124 per year. It features very basic GPS functions on the color screen.

The inReach Explorer model features full GPS capability including the ability to drop waypoints, navigate by compass and view route details. It does not display full topographic detail like a dedicated GPS unit. Purchase price is $380 and annual subscription fees range from $124 to $1280 depending on the service level. The basic service is adequate for infrequent emergency use.

PLBs and satellite messengers are definitely a worthwhile backup to your standard backcountry precautions, especially if you travel often in areas with poor cell service. You have to balance the purchase price and fees against the probability that you may need the SOS function and the ability to communicate by text from the backcountry. I personally keep a SPOT device in my hiking pack (it only weighs 4 ounces), but I have friends who have upgraded to the two-way text capable DeLorme devices. For serious expedition use in remote areas a more powerful PLB with GPS capability is a better choice.

Greg Foley is a member of Grand County Search and Rescue and has been a mountain rescue volunteer for 36 years. He can be reached by email at The GCSAR website can be found at or on Facebook/GCSAR.

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