Answering some of Roger’s questions:
I assume that the device does not use the same frequencies as a PLB/EPIRB – OK. But an activated PLB becomes a rescue beacon for SAR to home in on: does this device have such a beacon feature? (I assume not.)
You are correct on all counts. The PLB homing beacon is intended for short-range search, typically by aircraft. As others pointed out, the inReach sends your GPS coordinates with SOS messages; so does a PLB if it gets a GPS fix. But in some settings, GPS fixes are unavailable or way off.
Does the Iridium network really cover all the world? Oh well, how about Australia?
Potential Iridium satellite coverage is 100% global. Actual coverage is limited by US regulations (certain countries and regions banned via Iridium technology), and local laws that make carrying or using the device legally challenging. Australia isn’t on the banned list, yet :-)
How do I send an SOS with this device? Do I have to have a predefined emergency number like 000 or 112 and a predefined text message to send to that phone number? Or is there a separate SOS button or option?
When you push the physical SOS button, or activate SOS in the smartphone app, inReach SOS text messages go to GEOS for further processing, including notifying the appropriate local authorities. If your rescue service supports text or email messages, you could add those to your contact list and notify them directly through standard messaging. Activating SAR by text or email is not common in USA; I would also contact trusted friends and family, and rely on them to get help.
Please note: we do not carry, nor do we even own, a smart phone. And we don’t want to. I am asking about this device for medical emergencies: broken leg, heart attack, etc.
The inReach Mini is difficult and frustrating to use for writing and sending text messages without a smart phone. The larger and heavier inReach SE+ or Explorer+ are somewhat easier to use without a smart phone.
I am struggling to see any advantage of the Mini over a PLB when used purely for emergency.
PLBs are “activate and pray” – you don’t know if the message got through, and you don’t know if or when someone might show up. Generally they work quite well.
When you have two-way communications with SAR, you get confirmation that help is on the way, which can relieve suffering; you can tell SAR how many people might need help and of what kind (e.g. swiftwater rescue or cliff rescue); they can tell you when and how they might arrive so you could (for example) move to a helicopter-friendly location; and they can advise you on potential treatments for which you might not be trained or equipped. Doing all of that by text can be challenging; that’s why some people carry satellite phones instead.
Also, an inReach can send tracking points. If you are unable to trigger an SOS, someone at home might notice that you are overdue or stopped moving, and activate SAR with a pretty good last-known position.
Finally, a PLB activation means “get me out of here now,” and SAR volunteers literally risk their lives to get to you as soon as possible. With an inReach, you can tell SAR that your ankle is broken and you are in pain, but rescue tomorrow morning is OK. I would have a hard time living with a SAR volunteer getting seriously injured or killed because I had a broken ankle and activated a PLB.
And the PLB has much higher radiated power.
PLBs need more power to reach geosynchronous satellites that are about 50 times farther away than Iridium satellites. Many other aspects of satellite system design affect reliability as much or more than device power.
More background on satellite communications here:
https://backpackinglight.com/satellite_communications_sotmr_part1/
Hope this helps.
— Rex