Satellite Communication

I always feel conflicted bringing electronics into the mountains, but for extended and remote trips, I carry a satellite communication device. I don’t ever plan to press the SOS button, but two-way communication has proven integral to the success of my trips.

If you are carrying a satellite communication device, it is critical to update your contract/emergency contacts before each trip. I’ve made the mistake of not updating my emergency contacts, then discovering that the contacts were either with me on the trip, or out on their own trip, unavailable to relay information in the case of a real emergency.

It goes without saying that trip planning and self-rescue preparation is more important than carrying an SOS device. See Self-Rescue and Rescue Preparation page for some relevant notes.

Personal Locator Beacons (PLBs)

Personal Locator Beacons are reliable devices with one function: send an SOS signal.

  • SOS-only, no communication
  • Equivalent to EPIRBs (marine) and ELTs (aviation)
  • Stronger signal strength and more reliable than SENDs
  • The PLB response program is federally funded, so there is no subscription fee

Simply put, PLBs are the right devices if you want a reliable way to send an SOS signal. The major drawback is that you can only send an SOS, not any other information about the nature of the emergency.

If you purchase a PLB, you fill out NOAA’s PLB Registration Form, which registers the PLB id with your account, emergency contacts, etc. If you push the SOS button, the signal is encoded with location and beacon id. A multinational array of satellites, COSPAS-SARSAT, relays the signal to a control center, which uses the location and beacon identification to look up your emergency contacts and the nearest rescue assets.

Satellite Emergency Notification Devices (SENDs)

SEND devices include SPOT, DeLorme/Garmin inReach, Satellite phones, and other satellite messengers.

  • For-profit services that require a paid subscription
  • Some devices offer SOS and limited predefined messages (SPOT)
  • DeLorme/Garmin inReach devices offer SOS and two-way text messaging
  • Satellite Phones offer voice and texting
  • SENDs have weaker signal strength than PLBs, and are more prone to malfunction

As with the PLBs, SOS signals include location and device identification. The signal is conveyed to the GEOS Alliance (response center) via the private Globalstar or Iridium satellite networks, and the response center identifies emergency contacts, contacts nearest rescue assets, and responds to the device that sent the signal, if possible. Garmin provides a detailed summary of this process.


There are two SEND satellite arrays: Globalstar and Iridium. The Globalstar network has limited arctic coverage which is enough for me to disregard Globalstar devices (SPOT). The Iridium Network has full global coverage.

SPOT vs. inReach

The biggest difference between SPOT and inReach devices is that SPOT uses the Globalstar satellite array while inReach uses the Iridium network. If you are going to be using your device in Alaska, don’t get a SPOT.

Satellite Phones

Satellite phones are available for both Globalstar (Globalstar, SPOT) and Iridium networks. These are the most expensive (typically > $1000) of the SEND devices, bulky, and use heavy batteries. The phones can be used for voice or text messaging.

Even though the Iridium array is global, satellite phones are notorious for dropping calls at northern/southern latitudes and steep topography. A workable (and cheaper) solution is to text from the phone except for when voice is needed.

Given the cost, subscription fees, bulk, and how often they drop calls (in Alaska), I felt pretty justified not getting a satellite phone. However, the PJs (Air National Guard Rescue Squadron) are very clear about preferring people to have satellite phones. One PJ told me that he is able to read a lot into the situation based on the caller’s voice (panic, etc.). He also mentioned that voice is much more efficient for asking and answering questions.

Iridium has a new device (Iridium Go!, $800) that converts a smartphone to a satellite phone. Maybe if this device drops in price I’ll consider replacing my inReach.

The Evolution of inReach

The original inReach devices were made by DeLorme. In 2016, Garmin bought DeLorme.

  • DeLorme inReach SE: SOS and messaging, excellent battery life
  • DeLorme inReach Explorer: adds limited GPS functionality at significant battery draw
  • Garmin inReach SE+: Equivalent to the DeLorme Explorer, but in a better case
  • Garmin inReach Explorer+: full GPS functionality, including base maps and capacity to import/export routes

Both of the DeLorme devices have a serious design flaw: the locking mechanism to prevent accidental SOS activation does not work. I’ve heard of 10 Rescue deployments due to false SOS (including a 2018 trip I was on), and many more instances where the user was able to cancel the SOS within the 20-second window. This issue is getting surprisingly little press, here is an exception, by Andrew Skurka. Garmin has done a terrible job managing this issue, basically saying that the devices are being triggered by excessive pressure that they are not designed for. So… dozens of people have managed to apply ‘excessive’ pressure by carrying the device somewhere in their backpack. The Garmin-built inReaches have new cases, fixing the SOS-lock issue. However, Garmin still sells and provides contracts for the defective DeLorme devices.

If you or someone in your party has a DeLorme inReach, check for this defective behavior. I’ve heard of devices that do actually lock, but of the ~20 I’ve personally tested, all of them have the defective locking mechanism. Your options with these devices are to carry them somewhere they won’t be under any pressure (not in the bottom of your pack), in a hard case, or deal with Garmin’s poor customer service department to pay $150 to exchange the device for another DeLorme-built inReach.

The Future

The next generation of satellite messengers will be small devices that sync to smartphones. Garmin has recently released the Mini, Iridium’s GO! turns your smartphone into a sat phone, and startups like Somewear are near to having products on the market.

The Garmin inReach Mini is a new addition to the team. The Mini is designed to sync with a smart phone for faster message typing, but then of course you deplete your phone battery. Texting directly on the Mini is painful, but not much worse than the original DeLorme units. For such a small device the battery seems pretty effective… after one week of cold-weather use, I was at 70%. That included some track logging that I didn’t intend to do. For comparison, the Garmin Explorer+ was at 90% with a similar amount of use.

Which Device Is Best for You?

The rescue professionals would like you to have a satellite phone, so if you can afford it, that’s the best option. Otherwise, I’d go with the DeLorme inReach SE, Garmin inReach Explorer+, or Garmin inReach Mini, depending on your trip duration and phone/gps use. If you carry a separate GPS or use your phone, the battery life of the DeLorme SE can’t be beat (just remember to carry it in a hard case!), and the Mini takes care of the false-SOS concern. Otherwise, The Garmin Explorer+ is a great option… texting is easier and the fully-functional GPS serves as an excellent primary or backup GPS.

PS. Who Are These Rescue Assets?

Rescue assets are private and public rescue resources, including Search and Rescue teams, helicopters, the Coast Guard, etc. There is a hierarchy that governs which asset is deployed: private assets (e.g., Global Rescue, LifeMed) → municipal → State (Troopers) → Federal (Air National Guard, etc.). If the accident is within a National Park, NPS rescue assets are brought in before other Federal assets.


    1. I fully agree with the updated SPOT map. I have been using my SPOT with great success in the most northern parts of Sweden and Norway. Also in Greenland. No issues to send messages to let family and friends know that everything is OK. In 2013 I used the SOS button and aid came within less than 1 hour!

  1. Hi ! Hello, as a rescuer in my country I recognize the importance of communication with the injured person, but I think it is great to be disconnected. However, I have broken my gps, do you think the 66i would be a good option or would the Mini + gps be better?

    1. If you need to buy a GPS anyway, I would get the Explorer or 66i. I appreciate not having to carry separate devices, especially since I am carrying my phone as well.

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