Backcountry Pilot • Search & Rescue

Search & Rescue

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Re: Search & Rescue

Seems to be the epitome of a regulation where the punishment is irrelevant compared to the gain.[/quote]I guess it's not worth losing my license and livelihood over... in reality a 406 really makes the search area very small.

Sent from my SM-G960W using Tapatalk[/quote]

That is true, with a significant caveat: 406 beacons (with one notable exception) do not transmit a location.....they simply transmit a short burst every 50 secons with a unique identifier appended, which identifies the transmitter.

There are two sets of satellites which monitor 406: a geosynchronous satellite which covers all of North America except the very far north. And a system of polar orbiting satellites.

It’s the polar orbiting satellite system which provides location data for 406 ELTs. They do so using Doppler effect. In most of the lower 48, there’s a satellite pass about every 40 to 50 minutes. The first pass tells RCC there’s an active beacon and a pretty large possible area for location. The second satellite pass provides more data, and significantly better resolution. It’s the third pass that gives quite precise location data.

If there’s no fire, the airplane doesn’t sink in water or???, by the time RCC launches search assets, they’ll likely have pretty precise data on the location of the beacon.

On the other hand, if the worst happens, and the plane burns, even if the ELT gets off an alert, RCC will know who you are, and maybe what state your in (it could be a little better than that, but not much) and that’s about it.

Now, if your ELT had been connected to a GPS, That first burst transmission would have contained a precise set of GPS coordinates.

Which takes the search out of search and rescue.

MTV
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Re: Search & Rescue

mtv wrote:Seems to be the epitome of a regulation where the punishment is irrelevant compared to the gain.
I guess it's not worth losing my license and livelihood over... in reality a 406 really makes the search area very small.

Sent from my SM-G960W using Tapatalk[/quote]

That is true, with a significant caveat: 406 beacons (with one notable exception) do not transmit a location.....they simply transmit a short burst every 50 secons with a unique identifier appended, which identifies the transmitter.

There are two sets of satellites which monitor 406: a geosynchronous satellite which covers all of North America except the very far north. And a system of polar orbiting satellites.

It’s the polar orbiting satellite system which provides location data for 406 ELTs. They do so using Doppler effect. In most of the lower 48, there’s a satellite pass about every 40 to 50 minutes. The first pass tells RCC there’s an active beacon and a pretty large possible area for location. The second satellite pass provides more data, and significantly better resolution. It’s the third pass that gives quite precise location data.

If there’s no fire, the airplane doesn’t sink in water or???, by the time RCC launches search assets, they’ll likely have pretty precise data on the location of the beacon.

On the other hand, if the worst happens, and the plane burns, even if the ELT gets off an alert, RCC will know who you are, and maybe what state your in (it could be a little better than that, but not much) and that’s about it.

Now, if your ELT had been connected to a GPS, That first burst transmission would have contained a precise set of GPS coordinates.

Which takes the search out of search and rescue.

MTV[/quote]They are currently launching a third set of satellites that really complete the triangulation on the first burst. A couple are up already.
Trust me, I would love to hook them up as I believe it's the only way to go...

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Re: Search & Rescue

These units have a remote switch. Mount that front and center. When the shit hits the fan, push the button on that remote. Within 50 secons, someone in the Rescue Coordination Center will know who you are, where you are, and that you’re in an emergency.


One thing to keep in mind, however, is that that first burst sent out contains the gps position (If hooked up). If you were to land at the spot you pressed the button, all is good. But, if you were to fly around for instance, 5 miles, prior to setting down, Your spot will not be updated and the activation point is back in the same place, 5 miles back - not where you actually are. If the elt is still on however, the 121.5 for homing will still be going, but the gps position will not be updated. The triangulation method will still be good, but the GPS data would be of little value.

I'm not suggesting that its not unwise to activate in the air, but a plb activated where you stop would at least move the search area to the plb also. I don't know if the PLBs only transmit their position once like the ELT or not, but a Artex rep explained the 406 ELT Position workings as a spec requirement when the 406 units started with the GPS input. If it is, probably wandering away from its activation point of the PLB, may be the same principle.
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Re: Search & Rescue

Resky wrote:
These units have a remote switch. Mount that front and center. When the shit hits the fan, push the button on that remote. Within 50 secons, someone in the Rescue Coordination Center will know who you are, where you are, and that you’re in an emergency.


One thing to keep in mind, however, is that that first burst sent out contains the gps position (If hooked up). If you were to land at the spot you pressed the button, all is good. But, if you were to fly around for instance, 5 miles, prior to setting down, Your spot will not be updated and the activation point is back in the same place, 5 miles back - not where you actually are. If the elt is still on however, the 121.5 for homing will still be going, but the gps position will not be updated. The triangulation method will still be good, but the GPS data would be of little value.

I'm not suggesting that its not unwise to activate in the air, but a plb activated where you stop would at least move the search area to the plb also. I don't know if the PLBs only transmit their position once like the ELT or not, but a Artex rep explained the 406 ELT Position workings as a spec requirement when the 406 units started with the GPS input. If it is, probably wandering away from its activation point of the PLB, may be the same principle.


Well, that’s sorta true, but GPS typically update once per second. The ELT transmits every 50 seconds. So, every new ELT burst will have an updated position. Worst case is your position will be 50 seconds off. That could be a mile or so, but still pretty close. But waiting till you’re about to touch is likely a good idea.

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Re: Search & Rescue

I don't profess to be an expert, but the way it was explained to me, was that the GPS position is only transmitted on the first burst. Asked the reason for this, he said that that was in the specs first set for the 406 ELTs.
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Re: Search & Rescue

I can't speak to the other makes, but the ACK unit I have updated the encoded GPS in the hex code more or less continuously, not the first burst. I can't imagine any units actually have this limitation since it takes the Geosar system on average just under 10 minutes to acquire a valid message, process, and deliver it (less towards the poles, more towards the equator). Pointless to only send it in the first message, and I've never come across it in the standard.

If GPS is broadcasted, only a single message is needed over 98% of the time, and the average latent time is just a couple of minutes imstead of nearly 10 minutes.

It is a shame another byte or two couldn't have been added for speed, direction, and altitude. They are in the same NMEA sentence I send to my ACK ELT, but it does not parse them as they are not in the standard. They could be reasonable encoded in 1-2 bytes. It's too bad, but as long as the tx and antenna survive the landing, no prob.

Bottom line...if I tell my ACK it is in Tahiti for one message and Gnome the next, it keeps up with the changes.

Best to activate it in the air.
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Re: Search & Rescue

For you Canadians, there’s a 406 ELT made by a company called Emergency Lifesaving Technologies (E.L.T., getit?) Which comes equipped with its own onboard GPS. No connection required, and installation REQUIRES installation of the external GPS antenna. How would TC deal with that?

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Re: Search & Rescue

mtv wrote:For you Canadians, there’s a 406 ELT made by a company called Emergency Lifesaving Technologies (E.L.T., getit?) Which comes equipped with its own onboard GPS. No connection required, and installation REQUIRES installation of the external GPS antenna. How would TC deal with that?

MTV
Those are not certified for install in Canada Mike. So it's been dealt with by TC...

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Re: Search & Rescue

A1Skinner wrote:
mtv wrote:For you Canadians, there’s a 406 ELT made by a company called Emergency Lifesaving Technologies (E.L.T., getit?) Which comes equipped with its own onboard GPS. No connection required, and installation REQUIRES installation of the external GPS antenna. How would TC deal with that?

MTV
Those are not certified for install in Canada Mike. So it's been dealt with by TC...

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Yeah, that figures. They’re nothing if not efficient in covering the bases.... :roll:

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Re: Search & Rescue

I have an early Artex ME406 ELT, which I purchased and had installed very shortly after they were approved by both the FCC and the FAA, so it's been quite a number of years now. It was not equipped with a GPS, so when I had the 430W installed, that was one of the requirements. At that time, Artex had available for about $100 a tethering device, which the avionics shop obtained to connect the two.

However, today's similar Artex ELTs have built-in GPS. Whether they're approved by Transport Canada, I don't know. But they're available at Aircraft Spruce. I'd suggest contacting Artex to find out if TC has approved them, but my experience with getting fast and complete answers out of Artex has been miserable--good equipment, lousy or at best problematic post-purchase customer service.

Mine came with the then ubiquitous Velcro strap installation. A couple of years later, after the FAA banned that for all new ELTs, Artex came out with a substitute tray with a stainless steel strap. I obtained one and made the substitution. Mine is mounted on a structural member in the tail, right behind the baggage compartment. That structure was the tray that had the tail-mounted glideslope receiver on it, which was removed when the 430W was installed.

Whether this is part of the approval items or not, I don't know, but mine also has a Piezo-electric buzzer that goes off if the ELT goes off, so that it's pretty obvious if the ELT has activated after a hard landing. I do know that the red on-armed switch on the panel is a part of the approval--required by the 406 rule. But there's a potential flaw--there's also a switch on the ELT itself which has 2 different positions, off and armed. So I make a point after any maintenance that involved access to the tail cone to make sure that that switch is on, as I found it off after one of the annuals some years ago.

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Re: Search & Rescue

Cary wrote:I have an early Artex ME406 ELT, which I purchased and had installed very shortly after they were approved by both the FCC and the FAA, so it's been quite a number of years now. It was not equipped with a GPS, so when I had the 430W installed, that was one of the requirements. At that time, Artex had available for about $100 a tethering device, which the avionics shop obtained to connect the two.

However, today's similar Artex ELTs have built-in GPS. Whether they're approved by Transport Canada, I don't know. But they're available at Aircraft Spruce. I'd suggest contacting Artex to find out if TC has approved them, but my experience with getting fast and complete answers out of Artex has been miserable--good equipment, lousy or at best problematic post-purchase customer service.

Mine came with the then ubiquitous Velcro strap installation. A couple of years later, after the FAA banned that for all new ELTs, Artex came out with a substitute tray with a stainless steel strap. I obtained one and made the substitution. Mine is mounted on a structural member in the tail, right behind the baggage compartment. That structure was the tray that had the tail-mounted glideslope receiver on it, which was removed when the 430W was installed.

Whether this is part of the approval items or not, I don't know, but mine also has a Piezo-electric buzzer that goes off if the ELT goes off, so that it's pretty obvious if the ELT has activated after a hard landing. I do know that the red on-armed switch on the panel is a part of the approval--required by the 406 rule. But there's a potential flaw--there's also a switch on the ELT itself which has 2 different positions, off and armed. So I make a point after any maintenance that involved access to the tail cone to make sure that that switch is on, as I found it off after one of the annuals some years ago.

Cary
Interesting. All the Artex ELTs I've installed and seen have an "On" and "Armed" switch with no "Off" position. Then they have a jumper in the harness so it can activate if in the armed position when the harness is unplugged. This is different then the ACK models which hve a 3 position switch, "Armed", "Off", and "On".
I'm also curious which model if Artex has built in GPS. Most say they do but if you read the Q&A section they say that it requires connection to an external GPS source... unless the $4000 ones do. Bottom line is that it's silly that they put up such a fuss and jack the cost for so.ething that is very simple...

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Re: Search & Rescue

Frankly, the requirement for a certified GPS with the attendant install costs keeps lifesaving tech away from a lot of people.

A RS-232 GPS receiver:
https://www.amazon.com/USGLOBALSAT-USG- ... B00FIKU97Q

works fine. You just need a DC USB power supply ( a couple of bucks) or similar for the +5v to the antenna unit, and set the ACK up for 4800 baud. This GPS puck has a cord that isn't long enough to reach forward from a tail mount location all the way to the turtle deck in Cessnas. You will need to add a few feet of length. It's best to use a twin twisted pair set to extend the cable. Airplane cabins are electrically noisy places, and keeping things as short as possible is helpful. In a PA-xx, the runs are generally well within the cable length provided by the stock antenna.

The aircraft bus will power it up when you turn the master on just like any other avionics source and tell the ACK unit to start reading just like any other certified kit.

So spend a few thousand or spend well under a hundred. The outcome is exactly the same.
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