Emergency locator transmitters (ELTs) are one piece of equipment airplane owners love to hate. They dont work very well and they always seem to need replacement batteries. And, beginning this month, satellite monitoring of 121.5 MHz ELTs will cease, instantly making what didnt work all that well to begin with next to useless. This turn of events should not come as a surprise, since the U.S. Department of Commerce first publicized the Cospas-Sarsat decision to stop monitoring 121.5 MHz in November 2000. Cospas-Sarsat, of course, is the international organization charged with maintaining and monitoring the satellites listening for distress signals from ELTs and other devices.
For pilots and aircraft owners, one question is whether 121.5 MHZ equipment will continue to be adequate. Another is whether alternatives exist to upgrading to a new-technology ELT transmitting on 406 MHz, the frequency on which Cospas-Sarsat satellites will continue to listen. The answers arent that complicated. Lets first take a look at the two technologies, and then something in the way of an interim solution to have a 406 ELT on a 121.5 budget.
Who You Gonna Call?
The newer technology is superior in many ways, including its ability to transmit the units discrete identification and, if so equipped, the units current or last-known GPS-derived location. The new ELT standard (TSO C126) uses digital technology and 406.025 MHz is a huge step forward, but the FAA so far has refused to expand the ELT requirement to embrace 406 ELTs.
In our view, the decision on whether to upgrade to a 406 ELT should be made, at least in part, by considering where and how you do most of your flying. If youre like us, you mainly operate in the Lower 48 states of the U.S. and primarily in radar coverage while talking to ATC. In the event of a worst-case scenario, its very likely ATC will know exactly where you are.
Further, just because the Cospas-Sarsat satellites arent listening for your ELT, that doesnt mean no one else is. For example, at this writing, the FAA still has on the books a Notice to Airmen (Notam) FDC 4/4386, which states in part, “All aircraft operating in United States national airspace, if capable, shall maintain a listening watch on VHF Guard 121.5 or UHF 243.0.” Whether all aircraft comply with this Notam is debatable, but whats not debatable is many air carriers routinely monitor 121.5 and report to ATC when they hear an ELT (importantly, 406 ELTs also transmit on 121.5/243.0). Also, ATC facilities themselves monitor 121.5; if you crash within line of sight of a communications outlet, its likely someone will know it. Also still listening to 121.5 in the U.S. is the Civil Air Patrol.
In our institutional memory, based in part of reviewing almost every new NTSB accident or incident report, there are very few, if any, recent instances in which an ELT signal brought rescuers to the site of a survivable accident. In our experience, the opposite is true: Despite the FAAs ELT requirement, very few activations result in locating a crash site.
BELT? OR SUSPENDERS?
These days, then, given the proliferation of radar and radio coverage, coupled with cellphones and the convenient fact the majority of aircraft accidents occur on or in the vicinity of an airport, has the ELT outlived its usefulness? It depends.
If you operate outside the Lower 48-in Alaska, for example-the answer is a resounding “no.” But, wed argue the 121.5 ELT long ago failed to live up to expectations while technology-along with the likelihood of an airplane crashing and no one knowing about it-has marched on.
Whats that you say? Steve Fossett? Wed argue the circumstances surround Fossetts fatal crash are the exception that proves the rule: The Super Decathlon he flew was equipped with a 121.5 ELT, which failed to activate (probably due to excessive impact forces). Compared to the 406 MHz standards for emergency beacons, that technology just doesnt measure up any longer (presuming it ever did).
Our airplane, as required, is equipped with a 121.5 MHz ELT. As long as it remains healthy, well leave well enough alone. However, if we needed to replace our existing unit, we would not put another 121.5 ELT in its place, even if it would be cheaper and completely legal to do so. Instead, wed opt for a 406 ELT.
PLB Overview
Somewhere between those two extremes-sticking with 121.5 until they pry our cold, dead fingers from it and upgrading to a 406 ELT with all the bells and whistles-there is a middle ground. That middle ground takes two forms: First is going with a bare minimum 406 ELT, one that might even work after a crash. Second is a personal locator beacon, or PLB, which uses 406 MHz technology and can be purchased for lots less than an approved 406 ELT. But (and theres always a “but”), PLBs are not designed to withstand impact forces nor are they mounted for or equipped with G-force switches activating them in the event of a crash.
Instead, PLBs, as their name implies, are designed for multiple uses, not just aviation, and must be manually activated. For aviation purposes, carrying a PLB usually means sticking it in the glove box or in your flight bag, then remembering to activate it after “something happens.” One immediate downside to this approach, of course, is whether you or anyone else will be able to activate it. Another downside is whether the PLB will survive the impact in the first place. Its arguable that, if both answers are “no,” there likely is no hurry for authorities to find the crash site.
Upsides to a PLB include the intrinsic ability to remove it from the airplane and take it with you. Another is the lack of FAA regulations involving carriage, maintenance or testing of a PLB. Theyre relatively inexpensive, have a good record thus far and can do double duty as an ELT and a rescue-me beacon for the car, the boat or outdoor activities of all kinds.
All of this, of course, is predicated on the FAA not changing its existing regulations, which presently require carrying at least a 121.5 MHz ELT. If the agency did change its existing ELT rule, FAR 91.207, to mandate 406 MHz devices, a current-generation PLB would not comply.
Recently, sister publication Aviation Consumer took an in-depth look at current-generation PLBs, which are basically portable 406 ELTs without the crash-impact activation feature. You have to switch them on manually, something usually involving extending an antenna and pressing a button.
Current PLB designs are of two basic types: With or without a built-in GPS receiver. Sending the GPS coordinates to the satellite can narrow down the effective search area from within a three-nautical-mile radius when using 406 MHz Doppler shift techniques to 100 meters, which also eliminates the multiple-pass delay. That alone makes a PLB with built-in GPS the way to go, in our view.
A PLB must be FCC-approved before it can be registered in the U.S. And the free registration is necessary if owners expect to get the full benefit of a PLB, since each one carries a discrete digital signature thats part of its transmitted signal. All of the units Aviation Consumer examined have some means to test and verify their operation, but without radiating signals. Also, just because two PLBs meet required specs, doesnt necessarily mean they perform equally under all conditions.
Until someone markets an inexpensive GPS-equipped 406 ELT, a PLB with GPS may be best way to be found quickly after a remote crash. Starting this month, if you carry a 121.5 ELT, one of these PLBs may be the only way to get rescued at all.
