Heresy on 406 ELTs

August 18, 2010 by Bruce Landsberg

Untitled-1The news cycle continues regarding the crash involving former Alaska Senator Ted Stevens and several others. There have been numerous newspaper remembrances of the other big Alaska crash in 1972 that resulted in the loss of Congressman Hale Boggs and Rep. Nick Begich. That aircraft was never found and Congress mandated that all aircraft henceforth should be equipped with Emergency Locator Transmitters (ELTs).

The concept of having someone search for a crash immediately after an automatically-activated device signaled the impact’s location was seductive. However, the technology was certainly not ready for prime time as the devices often did not go off when needed but were pretty good at notifying the authorities of numerous hard landings that did not require rescue teams. The number of actual saves – where someone was still alive and found purely as a result of the ELT is reputed to be very small. You’ll remember the Steve Fossett search where the aircraft was equipped with a required ELT (not sure which model) that failed to activate.  The high number of failed and false activations is evidence that perhaps a totally different approach is needed.

Ironically, in this accident the ELT (reported to be a new 406 mhz model but that is speculative) failed to activate! Had there been personal locator beacons (PLB) aboard (and the passengers briefed on their use) it is quite plausible that the rescue would have come much sooner.

ADS-B is in the offing and would have given an immediate location of the crash site and yet, the public law as written, will not be allowed as a substitute for the 406 devices. The FAA is really pushing ADS-B since the entire ATC system will depend on it in a few years. Hmmm- seems like we’d want to provide incentive to equip yet Congress appears unwilling to allow pilots to use a far superior technology that has much broader application and is more cost effective. I’m obviously missing something.

Personally, I’d rather see pilots invest in airbags that really do work (disclosure – AmSafe, the airbag manufacturer, is a corporate sponsor of ASF safety seminars but this endorsement was unsolicited) and carry PLBs than depend the uncertainty of a hard-mounted 406 unit working as it was supposed to. The engineering is not so easy, as the record has proven – snap off the antenna as is known to happen occasionally in accidents and you’re toast. Additionally, a distinction should be made between Part 91 and Part 135/121 operations such that if I choose to fly without search and rescue (SAR) approved gear, that is my choice.

My friends in the search and rescue community will consider these views worthy of tar and feathers but Congressional mandates, often well intentioned, sometimes lead down the road to tar and feathers anyway.

Bruce Landsberg
Senior Safety Advisor, Air Safety Institute

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  • Willy Zeiger

    My question regarding the Otter crash and ELT before we speculate on rules is:
    Was the ELT a 406 and was it properly installed to a location that met the standars f TSO C91a and TSO C126? A TSO 126 improperly mounted will not work as well as a TSO91 of yesteryear.

  • Willy Zeiger

    typing corrections:

    My question regarding the Otter crash and ELT before we speculate on rules is:
    Was the ELT a 406 and was it properly installed to a location that met the standarss of TSO C91a and TSO C126? A TSO C126 improperly mounted will not work as well as a TSO 91 of yesteryear.

  • Jay

    SPOT takes the PLB concept a significant step further. Rather than relying on the pilot or passenger to activate it, SPOT has a mode that transmits your location every 10min to the SPOT servers. From there, your track can be broadcast to anyone you designate via e-mail or text messaging, and your position can be tracked in near real time using Google Maps. In soaring contests, we are beginning to use this information to put together a real-time view of the race for crew and spectators on the ground. In an emergency, SPOT allows you to send a help signal that will be passed to search and rescue. Tracking information provides a last known location if you can’t generate the help signal. Low cost, but requires an annual subscription that is truly cheap insurance. However, SPOT has many applications beyond aviation – it was originally developed for hiking.

  • Chuck Decker

    I’ve carried a PLB for years and would still install a 406 if I were convinced it would actually improve safety.

    Somebody supposedly did some math and determined that the FAA could pay to equip all GA aircraft with GPS / ADDS-B and still be operationally money ahead forever. Do you know of any serious, trustworthy cost analysis along those lines?

  • Chuck Decker

    Follow up — The SPOT idea is good and I understand that some flight schools and aircraft rental agencies are using this. A 10 minute old position report is better than nothing.

  • Dick Lawrence

    I agree with the thrust of the article, which among other points, leaves some pilot discretion regarding SAR gear. I have the required 121.5 ELT. I am considering the 406 units, either with or without GPS signaling. My experience with GPS reception is that it requires a reasonably clear view of the sky to work. And, from what I’ve read ELTs often suffer from antenna disconnect during crashes. The 406 unit without GPS has much greater accuracy than the 121.5 units, so that is already an improvement. So, it is a consideration whether or not to get the one with GPS. Regardless, I feel instinctively safer flying with a GPS PLB in my pocket which I’ve recently started doing. It seems like a pretty narrow window of survival between being unconscious and getting rescued as a result of the 406 ELT with GPS and being conscious enough to activate the handheld PLB. This should be my choice and as of now, it is!

  • David Abrams

    Avionics News recently had an article on 406 ELTs that stated that in 80% of the crashes the antenna sheared off and the signal was unusable. They are proposing a second antenna and a autoswitch to select it. This suggests the mandate to change to the new devices is less likely to make a difference as asserted.

  • Bruce Landsberg

    I should have mentioned SPOT. Earlier in it’s deployment there were reportedly some issues where an emergency situation took a bit long to get into the system. I have not checked the veracity but understand that they have made some changes to this.

  • Don Smith

    It is always good to have one’s opinion verified by someone with a lot more clout. See my article in the current issue of Fly-Low. ELTs are ineffective and a waste of money and a huge waste of time. We should find another technology that works, or that works a lot higher than the published 14% for ELTs of any manufacturer. Why don’t they work? They are not crashworthy. Hold one in your hand and look at it. It is a piece of plastic that would break if you dropped it on the hangar floor. They have cost us millions of dollars and delivered pennies in return. We should, as Landsberg (and I) propose, abandon them for superior technology. PLBs and ADS-B are on the table now, but surely we can come up with something that is better than the terribly flawed system we now require. Note that I didn’t say “use”. The only thing they are good for is causing the CAP to chase after false alarms.

  • John Townsley

    Like Chuck Decker who commented this morning at 06:53, I believe in redundancy. I carry a PLB registered and also have a 406 ELT installed in my aircraft. What’s more, I also file flight plans and (when available) use flight following for VFR flights.

    My take on 406 technology is that it’s a heck of a lot better than 121.5 mhz. However, unless there is continuous monitoring of a signal, initiation of SAR is still dependent upon unit activation. Let’s look at the activation failure before we discard the 406 mhz concept!

    You’ve probably heard the Navy Seal dictum: Two is one, and one is NONE! With just one emergency notification tool (the 406 ELT) the unfortunate occupants of the Otter in Alaska were reduced to “NONE” for immediate options. Sure a “SPOT” or PLB would have been nice (SPOT is an interesting concept, but far from the panacea the marketing would have us believe) – but the reality is they didn’t have a backup. No redundancy. Let’s not get political with the 406 debate. It’s not helpful in the short run, and it really isn’t helpful in the long run.

  • John Trail

    I find it interesting that only 1 comment mentioned flight plans. Our company always uses a flight plan, though it is usually a “company” plan. It’s simple, just make a phone call when you arrive at the destination and another before you start home.
    We have the “406” ELTs installed in company planes, and it did work when we lost a Cessna 207 in June 2009, we had a phonje call from the Rescue Communications Center within 10 minutes of the crash. We are also considering SPOT, but haven’t made the move yet although some of the locals have.
    Good article, and good comments !

  • Carl Simons

    Bruce,I’ve been bugging AmSafe about putting airbags in my 310 for years now,and the response has always been the same”no STC for the 310 yet from the FAA”!Is the FAA really concerned about safety?
    Carl Simons

  • Pete Pesaresi

    I fly a Cub. Low & slo and use it for cross country trips. How am I going to put in ADS-B? Does requiring ADS-B mean the end of my flights? Pete Pesaresi

  • Charlie Branch

    It looked like the impact force was insufficient to trigger the ELT, since the willows and other shrubs absorb a great deal of the impact. I adhere to the notion that what you carry on your body (inc. a PLB) is survival gear, and everything else is camping equipment. ELTs also lose signal once they sink below fifteen feet, so a PLB on one’s person would be much more valuable than a fixed mount on the aircraft. Isn’t it taught that we should use the airframe to save the passengers, and forget about trying to save the airplane?

  • Bradley Spatz

    I agree with you Mr. Landsberg. I’m favoring the PLB for my personal approach.

    As another data point, we just had a local pilot (N444WH) ditch at night 17 north of Key West about a week ago. Since the aircraft sank in 40′ of water quickly, the ELT provided no benefit even if it did activate (who knows).

  • Michael Fisher

    Don’t forget the Manual Activation switch.
    All 406 ELTs have to be installed with a manual activation switch, so you don’t need to wait for the crash to begin transmitting.
    In my flying experience, if you suffer engine failure you first try a restart. If that doesn’t work you pick a field and make your preparations. That’s a good time to flick the switch on the ELT so even before you’ve landed it is transmitting your emergency to the 406 satellites – the only true global emergency rescue system.

  • Bruce Landsberg


    Regarding the low and slow crowd, that’s one of the challenges of ADS-B and AOPA has voiced concern to FAA about that. My understanding is that battery powered low cost ( whatever that means) equipment is in testing so that all aircraft could potentially be seen.

    It does have the potential to reduce midair collisions between VFR aircraft pretty much anywhere. The capstone project in AK was doing some testing on this.

  • Troy Hamon

    Bruce, thanks for writing this. I’ve been unable to talk myself into being excited about the new 406 ELTs. They cost a fair bit but provide no benefits to the pilot or aircraft compared to an accurate tracklog from a GPS. Since Spot has figured out how to send a tracklog, other vendors are getting into the game. Any of those devices, or perhaps the ADS-B option, would allow a very targeted search or perhaps even a pinpoint location. The ELT might be able to do the same, if they can ever figure out how to make a device that actually works in a crash. Perhaps the inertial trigger would need to be in the panel instead of the device. Anyway, it seems odd that we have a certified requirement for something that amounts to an ongoing failed experimental product, while more capable technology in use in all facets of travel are not approved or, apparently, approvable.

  • Lawrence Stalla

    Bruce, I bought and installed an Artex GPS NAV-enhanced 406 MHz ELT almost exactly 12 years ago (in fact, I believe mine was the first “long format” — alternate beacon ID + GPS location — U.S. ELT registered with COSPAS-SARSAT), so I have some experience relative to your original post and some of the other comments. First, under TSO C126, this ELT comes with both an in-cockpit activation switch, and an indicator light to warn of inadvertent activation. As a backstop to the G-switch, I’ve resolved to throw the in-cockpit switch if an off-airport crash appeared inevitable. I’ve never had an inadvertent activation, but it’s nice to know the indicator light (plus a buzzer in the tailcone) will warn me of one. Second, I’ve participated in several annual 91.207(d) checks, and never has the G-switch failed to properly activate at about 9 forward Gs. Third, the inner workings of the ELT were encased inside a pair of hard Lexan shells that I’m confident will let them survive any crash that my passengers and I could. As you noted, though, my one criticism of this ELT at the time of original purchase was that it came “standard” with a rod antenna that I doubted could have withstood as many forward Gs as I can without snapping off. So, I bought the more robust low-profile tri-band blade antenna as a $750 option — a much more crashworthy choice. My total cost, through installation, for all of this search-and-rescue peace-of-mind was about $8,000 in 1998 (the price has dropped since then). Yep, eight large, but then, you get what you pay for.