The person in that article was using SPOT, not a PLB.

Actual PLBs (not SPOT) have a backup strategy in the event the GPS signal is obscured by mountains.

If the device can't get a reliable GPS fix, the satellites will resort to measuring doppler shift as they pass overhead to locate the transmitter. It's slower (takes several passes of the satellite, so we're talking hours) and less accurate, but it will get rescuers to the general direction.

From there, PLB devices also transmit a low-power homing signal on 121.5 MHz (the aviation distress frequency) that SAR teams can locate using radio direction-finding equipment.

Thanks for the info. Although, in general, I assume a device that allows you to have two-way communications with SAR is preferable even if a PLB might have been better in this ultimately fatal situation.

Yes, two-way communication is a huge benefit since you can explain the problem and the responders can give advice in addition to ETAs.

However, a device like the Garmin inReach requires an active subscription for the SOS to work. If there's a glitch with your credit card and the service becomes inactive while you're on travels, it might not work.

Another difference is that an inReach SOS message goes to the Garmin-run https://www.iercc.com/en-US/about/ rescue coordination center who will the relay to rescue services.

Whereas a PLB or EPIRB communicate with the Cospas-Sarsat system and is handled directly by government rescue agencies (https://www.sarsat.noaa.gov/mission-control-center). While the Garmin service works great, I have more trust in the USMCC being always responsive than any private company.

So the best advise is to have both. I have an EPIRB (for boating) and a couple PLBs in addition the the Garmin inReach. I use the inReach for casual messaging but if I ever have a real emergency I'll activate the PLB and EPIRB first and only afterwards start trying to message via the Garmin.

My understanding is that SARSAT is the only option that has satellites in orbits above LEO, and thus generally better coverage. So if it's down to one thing only, I'd pick the PLB just on the basis that, in a serious emergency, it's more important for help to come at all.

Note that http://www.catskillmountaineer.com/reviews-winterhikingKM.ht... for example says Kate did not have a PLB, but only a SPOT (one of the many commercial products in this space)

PLBs are tested down to -40° so it might have stayed working for longer as the weather got worse. It is of course impossible to say if Kate might have survived under other circumstances except that (not very interestingly) if she's decided the weather was too awful and aborted she'd almost certainly live.

It's been a while since I read the book on this. I'm not sure if it got into the exact equipment or not. Certainly if SAR had an accurate fix from the beginning there would have been at least some hope for a rescue.

The book was interesting mostly for all the SAR detail. The accident, sadly, was mostly in the category of--however fit and well-equipped you are--don't try to beat a very bad incoming storm on an exposed ridge line in the middle of winter. If she had turned around at Madison Hut or wherever she'd have been fine.

I only meant that the devices, if properly maintained, can be trusted to do their job as best they can and not say "PC LOAD LETTER" and expect you to troubleshoot it. A successful rescue is never guaranteed.

Those of us who are programmers usually default to "If it's not tested end to end, it won't work," and that is the sentiment I was responding to.