All active outdoor adventures should consider carrying some sort of signaling device in the event of dire emergency. If you’re even moderately injured in the backcountry, your chance of self-evacuation is minimal. And if you’re seriously injured, rescue response time may mean the difference between life, death, or lifelong disability. Trailhead registration, leaving an itinerary, and having a responsible person to notify authorities if you don’t return on schedule are all important safety steps, but without some sort of emergency signal, if you’re injured near the beginning of a weeklong trip, you might lay there for days, knowing that search efforts haven’t even begun yet.
Basic devices like whistles, flashers, signal mirrors, and pocket flares are all useful for helping searchers hone in on your final location, but they’re rarely useful for triggering rescue response. In more developed front country areas (and even in remote Yellowstone) cell phones can work surprisingly well for sounding the alarm, especially tri-band digital/analog-capable phones on AT&T or Verizon. In ski areas or popular national park environs like Yosemite Valley or Zion Canyon, even FRS/GMRS radios set to channel one/code one can often get you through to someone, even if it’s just a tourist family near the visitor center.
But most wilderness travelers should use some sort of signaling device that works off satellites. It’s the only way you can reliably call for help from a remote setting.
So today I offer the first of three posts examining the long-range emergency signaling devices commonly used by wilderness trekkers: personal locator beacons (PLBs, satellite phones, and SPOT satellite messengers. The choice between them is basically a trade-off between emergency alarm reliability, and richer communication. Each is ‘the best’ for a different user. All these items have details beyond what we can cover here, so follow the hyperlinks for more information. And if you’re actively shopping for an emergency signaling device, we suggest you rent before committing to a choice.
PLB 101: The Basics of Personal Locator Beacons
For the most reliable help call possible, world-wide, personal locator beacons are the ticket. Modern PLBs work by transmitting a robust, 5-watt 406MHz signal that’s received by an international constellation of government and military satellites called the COSPAS-SARSAT system. COSPAS-SARSAT uses U.S. and Russian low-earth-orbital (LEO) satellites on polar orbit, and geosynchronous (“stationary”) satellites operated by the U.S. and European Union. All PLB reception and rescue coordination is run by government entities.
The COSPAS-SARSAT satellites relay PLB emergency signals to one of 38 automatic ground receivers around the world. The signal is then relayed to a mission control center in the country where the signal was received. Once the signal’s location is determined, relevant rescue authorities in that area are contacted. In the U.S., local authorities like county sheriff’s and land managers are notified of PLB distress calls by the Air Force Rescue Coordination Center at Tyndall Air Force Base in Florida. The system is triggered, world-wide, regardless of where the user is or what country their beacon was registered in.
Rescue coordination centers can read a digital serial number encoded into PLB signals. That lets them access the individual unit’s registration information, and call emergency contacts the beacon owner listed at the time of mandatory registration. This allows the coordination center to confirm the validity of the distress call and obtain additional information like your age, blood type, or allergies.
PLBs using the 406MHz signal penetrate cloud cover, forest canopies, and narrow gorges better than all other portable handheld signaling devices (although cavers and people in ultra-tight slot canyons are still out of luck). In temperate latitudes between 70 degrees North and South, the geosynchronous satellites relay distress signals and their location to rescue centers almost immediately. In polar regions it may take up to an hour for a satellite to crest the horizon, relay the signal, and use Doppler calculations to obtain a rough position fix.
Most PLBs now come “self-locating” (i.e. GPS-enabled, either with onboard GPS or an NMEA cable interface) which allows rescue coordination centers to pinpoint signal location within 100 meters. All U.S. PLBs must also transmit a 121.5 MHZ signal (relic of an older standard still used in aviation) which helps rescue teams home in closer on non-GPS PLB signals, since satellite Doppler calculations can only pinpoint victim location to a two-mile radius.
PLBs themselves must pass rigorous physical testing for reliability in cold, wet and shock-prone environments. They come in two types, one rated for slightly colder conditions; Class I PLBs operate from -40F to 131F; Class II PLBs from -20F to 131F. Most are the size of a jumbo candy bar, cost $500 to $700, and weigh from 8.5 to 12 ounces. Loaded with lithium batteries they store for years, and are waterproof to a one meter depth.They have a self-test button, and the beacon activation button is usually under some sort of seal to prevent accidental triggering. About the only weakness to a PLB is the fact that you need to be conscious to activate the unit – a potential drawback in sudden falls.
For best transmission, hold the unit with the antenna vertical. Once the beacon has been used and the emergency’s over, it’s recommended you change the batteries, since the 5-watt signal drains power quickly and handheld PLBs are only required to have about 24 hours of transmit time, which may be important for rescuers homing in on the 121.5 MHz auxiliary signal.
A PLBs greatest strength is also its greatest weakness; It’s ideal for triggering a full scale emergency rescue anywhere on the planet, but that is all it does. You can’t check in to say you’re OK. You can’t say “No rush, it’s just a broken ankle.” You can’t say “Never mind, I found the trail again.” You can’t give rescuers any advance idea as to medical conditions or multiple victims.
Last but not least, triggering a PLB is a big deal. It initiates a potentially international rescue effort. Each signal must be treated as a dire life-threatening emergency. In the U.S., hoax distress calls are a federal felony punishable by up to $250,000 in fines, 6 years in jail, and restitution costs for the SAR effort. (Hint: Keep kids away from PLBs.) In most cases, the first response will be a helicopter with emergency medical technicians on board. It’d also be wise to have your credit card handy, and possess solid health and rescue insurance.
PLBs are pricey, but after purchase there are no additional costs other than replacement batteries. Rental PLB's are commonly available, and reasonably priced – an excellent solution for folks who rarely do committing trips. On the downside: there’s also zero “toy potential” with a PLB, unlike a GPS, cell or sat phone. But if rock-bottom EMS response time in dire emergencies is your biggest priority, or you regularly adventure in polar or international regions, then a PLB is your best choice.
However, because of the slim communication potential of PLBs, other devices may be more suitable to your needs. We’ll cover those in following dispatches. Stay tuned. – Steve Howe
P.S. If any readers out there have used PLBs, sat phones, SPOT beacons, FRS radios or cell phones in real-life emergencies, we’d love to hear your story. See the ‘comments’ button below.