Kath and I generally hike alone. Rarely does anyone know where we are, because we tend to plan last-minute, according to the weather. We’ve always known that self rescue was our only hope in case of emergency. And we’ve always been comfortable with that. But as our backcountry ventures became longer and more challenging, the chance of injury increased, and the consequences of a navigational error became more severe. We eventually decided to carry a personal locator beacon (PLB).

A PLB is a tracking transmitter that allows the detection and location of hikers in emergency situations. PLBs interface with the worldwide service of Cospas-Sarsat, the international satellite system for search and rescue (SAR). When activated, a PLB sends a distress signal. The signal is detected by non-geostationary satellites, instantly alerting the local SAR authorities that you are in need of rescue and providing your GPS coordinates. Ideally, a PLB will ensure you are rescued within the golden day: the first 24 hours following a traumatic event, during which most survivors can be saved. Since the inception of Cospas-Sarsat in 1982, tracking transmitters have assisted in the rescue of more than 28,000 people in more than 7,000 life-threatening events.

Our first PLB was a MicroFix 406 made by ACR Electronics. It retailed for $740. Since then, the price of PLBs has decreased significantly. Here are the specs for the current model:

MicroFix 406 PLB • www.acrelectronics.com • cost: $400 • annual subscription: none • size: 1.4” x 5.85” x 2.21” • weight: 10 oz • battery life: 5-year replacement (or after emergency use) • battery replacement: must return to manufacturer • transmit time: 40 hours

Over the past couple years, we’ve heard and read about the Spot Satellite Messenger. It has appealing attributes. It’s smaller than the MicroFix and weighs half as much. Here are the current specs:

Spot 2 • www.findmespot.com • cost: $170 • annual subscription: $100 – $150 • size: 3.7” x 2.6” x 1” • weight: 5.2 oz • battery life: six days in SOS mode • battery replacement: user replaceable • transmit time: unlimited, if batteries are continually replaced

Weight and size, however, are not the only differences between the MicroFix and the Spot. The MicroFix is an all-or-nothing device: push the button and the cavalry comes. The Spot offers many service features (http://www.findmespot.com/en/index.php?cid=103) in return for your annual subscription fee. Also, the MicroFix is a true PLB, relying on a network of international government satellites. The Spot uses a commercial satellite network.

The various messaging features of the Spot hold no appeal for us. We don’t want to keep in touch with friends and family when we’re in the backcountry. If you want to send frequent “I’m okay” messages to your mother or you buddies when you’re on the trail, perhaps the Spot is for you. All we want is a means of contacting SAR if we’re ever in a life-or-death predicament.

The Spot can do that. But is it as reliable as the MicroFix? We don’t think so.

Bear in mind, we have no personal experience with this. We’ve never been lost or injured. We’re capable cross-country navigators, we’re always prepared for emergencies, and we make conservative decisions that so far have ensured our safety. So we’ve never needed to activate our MicroFix. But if we had to push the button on a MicroFix or a Spot, we’d be more confident of a speedy rescue with the MicroFix. That’s because we trust Cospas-Sarsat more than we would Globalstar. One is regulated, the other is not.

Here’s a summary of how these devices differ:

SPOT • transmits at 1610 MHz via the satellite network operated by Globalstar, a commercial company • is unregulated, because Globalstar is a private, for-profit corporation • does not transmit with enough power for the signal to be tracked by itself; the GPS transmission is the sole means of determining the unit’s location • contacts local 911 services when an SOS signal is received

MicroFix • transmits at the standard emergency radio frequency of 460 MHz via the Cospas-Sarsat satellite network originally developed as a joint effort of governments worldwide • is regulated, because Cospas-Sarsat is a non-profit, intergovernmental organization • transmits with enough power for the radio signal to be tracked by SAR • also transmits coordinates via the radio signal • contacts SAR when an SOS signal is received

The web is rife with opinions on the relative merits of these devices. Try googling “Spot vs. PLB” if you want to read about others’ personal experiences with them. We’ve read several dozen such reports, many of which describe how the Spot disappointed or failed. To us, it’s apparent the Spot’s reliability is suspect.

An emergency-signal transmitter whose reliability is suspect? Imagine…

Kathy: I can’t stop your arterial bleeding!

Craig: That’s okay. Just push the button on this device whose reliability is suspect.

That’s why we continued carrying the MicroFix on every hike. But at 10 ounces, it adds noticeable heft to my pack. So now that the battery is due for replacement, we’ve been looking for a lighter PLB. We’ve found two models:

McMurdo FastFind 210 • www.mcmurdo.co.uk • cost: $225 • annual subscription: none • size: 1.34” x 1.85” x  4.17” • weight: 5.3 oz • battery life: 5-year replacement (or after emergency use) • battery replacement: user replaceable • transmit time: 24 hours

ACR ResQLink • www.acrelectronics.com • cost: $250 • annual subscription: none • size: 3.9” x 1.9” x 1.3” • weight: 4.6 oz • battery life: 5-year replacement (or after emergency use) • battery replacement: must return to manufacturer • transmit time: 40 hours

The FastFind is a good choice. It’s significantly smaller and lighter than the MicroFix and presumably more reliable than the Spot. It’s also available now, for example at Mountain Equipment Co-op stores in Canada, and REI stores in the U.S.

The ResQLink is our choice. It’s ever-so-slightly smaller and lighter than the FastFind. ACR describes it as “the world’s smallest, lightest PLB.” Presumably it’s as reliable as the FastFind or MicroFix, and more reliable than the Spot. And the ResQLink’s transmit time of 40 hours bests the FastFind’s 24 hours by a wide margin. The ResQLink, however, is not yet available for purchase. The release date is supposed to be next month: June, 2011. As soon as we purchase ours, we’ll let you know.