Wednesday, March 10, 2010

406 MHz

When you get in my airplane, part of your safety briefing includes me telling you where in aircraft the Emergency Locator Transmitter is installed. (It's in the vertical stabilizer, marked on the outside with a sticker, and can be reached by tearing off a panel. You don't need tools to get it off if you're willing to destroy it in the process, and if you need it it's an emergency, so you should be). You shouldn't need to physically reach it anyway, as it's supposed to start transmitting automatically in the case of a crash, advising the world of the need for rescue and the location of the accident. ELTs are required by law to be in almost all aircraft operating in Canada. (There are a few exceptions for things like balloons, skydiving operators, and delays in repairs). The problem is, the law no longer requires the ELT to transmit on the most useful frequency. It's not that the law changed, it's that the useful frequency changed and the law didn't. Satellite monitoring of 121.5 was turned off over a year ago, leaving only the new 406 MHz frequency.

Below is an informative Transport Canada video on the advantages of the 406 MHz units, made somewhat entertaining by its "historical" character. Watch for the old-style green CFS in the tower. I love that the "typical Canadian pilot" is a while male in a Skyhawk. About right, really. The point of the video is to encourage Canadians to embrace the new 406 MHz ELT technology, because they are monitored by satellite and send information on the registered owner of the ELT. Without satellite monitoring, the old ELTs that transmit only on 121.5 MHz are useful only for informing people monitoring that frequency that there may be an airplane crashed in their approximate vicinity. Or maybe just a faulty microwave oven.

Embedding this video seems to crash some people's browsers, so click the check mark in the two-line table on this page.

The unchanged law wasn't an oversight. It was supposed to change years ago, calling for the minimum legal ELTs to transmit on 406. There were handbills and videos and stickers and probably mousepads and t-shirts too, all promoting the new standard. But there affordable general aviation ELTs didn't exist. Canadian advocacy groups said, "Hey, wait, these exceed 20% of the cost of some of our members' airplanes!" Transport Canada funded a 2008 study into reducing the cost of 406 MHz ELTs. Aviation supplies are expensive enough to start with, but usually Canadians can rely on getting the best possible prices as a result of the competitive American market. There are so many GA pilots in the US, that anything they want to buy is available from multiple competing suppliers and innovation plus economies of scale bring the price down. But in this case Canada was mandating equipment that was not required by and was not particularly useful to most US pilots. Alaska is like most of Canada, but flying in the rest of the US being out of radar contact while enroute is so rare that the controllers point it out to you with some concern. Not only were the Americans not going to sell us cheap ELTs, but they were opposed to the regulation.

This US pilot group discussion typifies their concerns, back when Feb 2009 was the deadline. US pilots have three understandable objections.

  • They don't want to buy 406 MHz ELTs just to legally cross the border, but the regulation effectively imposes a three thousand dollar per aircraft fee for operating in Canada.
  • The discussion demonstrates a national difference in philosophy with "If I waive Search and Rescue service, I shouldn't have to pay for an ELT." I think this is likely the same difference that makes people on opposite sides of the border feel differently about government-funded healthcare. Canadian SAR looks for everyone who is known to be missing, no matter how poorly prepared they are, so we don't consider it out of line to require a level of preparation that will save all taxpayers a lot of money on UNSAR. And of course Americans can't be expected to care about Canadian taxes.
  • The pilots believe that having flown in the US, which is itself huge and has some areas of low population density, that they understand the barrenness of Canada. The latter has less than a tenth of the average population density of the former, and the population we do have is more asymmetrically distributed.

Government kept pushing the effective date of the new regulation forward into the future. A requirement to carry a 406 MHz ELT is still not in the current rules. They haven't forgotten about it, but it's dropped off the front page. The only FAQ question about ELTs on the TC site is about the angle you can put the antenna on, on a helicopter. It's still pending.

Meanwhile there's nothing to prevent Canadians from replacing the old ELTs with modern units that broadcast on 121.5 and 406 MHz. Relying on the 121.5 broadcast means hoping that someone hears it and can home in on it by reports of where the signal is audible at what strength.

ELT signal from inside cat


Unknown said...

I posed the question if people still even monitor 121.5Mhz on my blog back in February.

Similar topic to this post.

jk said...

Dear Aviatrix,

This company ( has a $600 USD 406/121.5 ELT that is just now after a years' worth of delays appears to be near shipping. Of course installation is extra but this is a real game changer in terms of price.

Like other 406's it can be interfaced to a panel mounted GPS (if you have one that is!) and if this is done, I think its chief advantage is instantly sending your position to waiting satellite. Of course, if you don't have a GPS interface or the ELT is destroyed/submerged/does not activate on landing, it is marginally better than 121.5 (except for eliminating the false alarm problems 121.5 has).

After learning all about 406 from a local civil air patrol presentation here (CAP is a US Air Force civilian axillary organization that conducts a lot of search flights), I decoded to invest in one of these: $300US was a great deal. It even has a built in GPS so it will blast my coordinates up to a satellite after acquisition. The advantage here is that I can take it with me (for example, if I were to ditch the airplane). If I could hang on to it.. chances are I'd be located quickly. I mounted it close to my airplane's cabin door and brief passengers on use, as well as that it needs to remain on their person (or mine) when exiting the airplane in the event of a forced landing.

Blake: I have two radios. When not in use for something else I monitor 121.5. In the past couple of years I've picked up 3 ELT/EPIRB signals on 121.5 and reported them. One was a real incident involving a fishing boat that sunk. I don't think it was my report that found them since they had a 406 EPIRB to get the initial message out, though.

mattheww50 said...

As Aviatrix knows, I have pushed her to own and carry a PLB like the Fastfind for some time. The 406Mhz services offer several important advantages over 121.5 Mhz.

1). The Beacon carries an Identifier, so you know who (and often what) you are looking for.

2). The Beacon has a provision for a data payload (a GPS position). As the US Coast Guard put it, These devices are taking the Search part out of Search and Rescue.

3). The 406Mhz devices are required to be much higher power than the 121.5Mhz devices (Watts versus Milliwatts), and more stable transmitters. The result is the 'fix' from the Sat even without a GPS payload has a CEP of about 5km, compared to 20km for the 121.5 Mhz.

4). The 406 Mhz frequency is monitored by sats in geosynchronous orbit. The result is the fact that the alarm has gone off is picked up almost instantly, and if GPS equipped, will also provide the location.

By contrast it could take up to 90 minutes for a Sat to come in range of a 121.5Mhz beacon (if they were still listening).

And yes, I own a PLB (an ACR unit). I practice what I preach. There are some things you buy because your life may depend upon it. A PLB is one of those things.

What is generally not known is the agency that handles PLB/EPIRB registration in the USA is NOAA, and they will happily register a Beacon with a US ID to an address and contact point outside the USA.

grant said...

I agree that commercial operators should all be upgrading asap to the 406 units. Not so the rest of the recreational flying community. There are some very good Personal Locator Beacons that are a lot cheaper and probably more reliable and stay with the pilot.

If TC would get their act together and listen to the recommendatons of COPA, this could have been "solved" by now. But when you've already spent a ton of money on one system, you then apparently need to force everyone to use it.

Anonymous said...

From YVR.

Good post with interesting comments

Jeremy said...

I can't say I understand why the permanently mounted beacons cost thousands, when 406Mhz PLBs are available for under US$400 as already noted.

Surely the regulations should encourage 406 MHz PLBs as an alternative for private flying, for those who can't afford a fully installed ELT? That's got to have a lot more safety value than the 121.5, right?

Or is this not really about saftey value but providing a reliable source of income to avionics manufacturers?

Note: I own a "Spot" device that I carry while boating and hiking. Although I'm not flying privately at the moment, when I am able to get back into flying the PLB will definitely come with me. I would like to upgrade to an official 406MHz one but the SPOT system is pretty useful too.

Aviatrix said...

Jeremy: Everything certified for aviation costs about ten times as much as the regular variety, so that's par for the course.

A PLB has about half the battery life of the aviation ones, does not have acceleration activation and does not comply with the ICAO standards. The purpose of the proposed legislation is to normalize Canadian law with ICAO regulations (which introduced 406 MHz years ago). There's nothing in it to discourage carrying PLBs, but they aren't going to put in a halfway measure.

mattheww50 said...

A PLB actually has the same battery shelf life as an EPIRB, however the 'run time' after activation on a PLB is about half of what is required from a EPIRB.

The other difference is an EPIRB needs to operate to -40C, a PLB doesn't, although many manufacturers sell a larger battery to enable operation to -40C as an option.
However in terms of signal output, and beacon ID and content, the PLB and EPIRB are identical. The onlyway to tell the difference between a PLB and an EPIRB going off at 406 Mhz is by looking up the device type from Beacon ID registration!

US PLB's however have to transmit in morse code, the letter P on the 121.5Mhz output (which most hvave).

As for cost. I am reminded of an experience my late father had. He had an instrument that went to the Moon on the final Apollo mission. They built a fully functional mockup for about $20,000. The actual device that flew cost $500,000. By the time you have done all the necessary documentation,built to flight standards, and used 'flight grade' components, and complete the requisite testing, the costs end up absurd.
Sometime check out the cost of a Coffee Pot for Galley on a commercial jet liner.

dpierce said...

Reminds me of the much over-hyped story here in the US of the $700 Orion P-3 toilet seat. A super-limited run of a custom lavatory molding that has to meet flammability / high-heat requirements is going to cost $700. It's actually surprising it wasn't more.

In any case, P-3 guys are lucky to have a real lav as viewed by Herk crew.

Aviatrix said...

A Herc crew is lucky to have a lav at all. Ever tried to pee in a bag while sitting at the flight controls?

Sarah said...

.... with no autopilot?

You go,girl!

verification word: noundui, a thing I will never have.

dpierce said...

They didn't give you the details of the "honey pot"? It normally sits on the left side of the ramp. Fancy squadrons will even improvise a curtain.

Belgium said...

Read this blogpost from recently:

Cheap sattelite based emergency beacon.

A Squared said...

"It normally sits on the left side of the ramp."

On the ramp? Seems that would promote spillage. Ours sits just aft of the 245 bulkhead

Aluwings said...

COPA studied the effectiveness of ELTs and failure rate for one reason and another - in light aircraft. I'd personally feel more secure with a PLB strapped to my arm. If I'm not "there" to activate it when needed, then I don't care how long the batteries last.

Aluwings said...

And come to think of it - the SPOT PLB doesn't need to be activated - it leaves a "bread-crumb" trail that should get searchers in the right vicinity.

Sarah said...

Yep Aluwings, "spot" has been popular with glider pilots in the sparsely populated western US for the reasons you state. Most people strap it to their parachute harness, so even after a bailout it should be useful. For gliders, sudden incapacitation ( midair, hitting granite clouds ) aren't problems for us, but forced landouts are. There would be time to push a button even before the forced landing.

The 'breadcrumb' train may be less useful in emergency unless you have someone monitoring your progress on the ground, friends, family, crew ( company? ). They'd have to look at a website, and you'd have to have it turned on and facing the sky.

I don't have one - yet - I fly in the US midwest, which has a farmhouse every couple miles. Not to mention radio/radar coverate, etc. etc. I don't even have a 121.5 ELT in my sailplane.

Aviatrix said...

I flew with someone who had a Spot, and the breadcrumb trail didn't work -- even in an ultralight in a non-mountainous area -- sending her SO into paroxysms of worry. That plus the US$100 annual subscription fee sour me on that particular brand.

Critical Alpha said...

With respect to ELT's/EPIRBS a review of crash reports at ATSB will leave you wondering at the high failure rate. These items don't activate when they are supposed too at an alarmingly high rate. I'm sure that there are similar failures reported in Canada, the US and elsewhere. There is a need for improved activation standards.
Nevertheless 406MHz beacons are critical to safety. Sailing we have a float free 406 beacon and have had for over 6 years. We also carry PLBs when offshore for every person on deck. This means that if someone goes overboard they have a beacon to pop. I wouldn't be without it.
Similarly, in an a/c, if outside the circuit area I _wear_ a 406 PLB around my neck, regardless of of whether the a/c is equipped or not.
If you've ever participated in a fruitless search for a lost a/c you would wear one too.

Anonymous said...

Regarding the failure rate of these units, I am not sure how much data there is on EPIRB's, but at least in Australia, the ELT failure rate was a genuine horror story. Out of 33 crashes at one point in the early part of the last decade, 31 had failed to operate. Analysis revealed that they either broke the antenna cable on impact, or were incinerated in the fire resulting from the crash.

So it suffices to say that I invested in a PLB early on.

However the record with EPIRB's likely to be better since the activation of a PLB or EPIRB is detected almost instantly now. By contrast it could take up to 90 minutes for COSPAS/SARSAT bird to come overhead and pickup a 121.5 Mhz ELT. I.E. the alert may be transmitted BEFORE the unit is incinerated.

Michael5000 said...

I can't tell if you are such a wicked good writer that you can make a history of aircraft equipment policy gripping to someone who has never been in a cockpit, or if I am just a big second-half aviation dork. I think probably both.