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406 ELT-GPS interface

Bud K

Well Known Member
I am looking to upgrade to a 406mHz ELT. The ACK E-04 unit says that it can interface with a Garmin GPS through a pair of RS-232 wires (plus a power and ground wire). My question is 'what is the benefit of this interface?'
 
GPS Position

It provides your current GPS position to the ELT, which the 406 ELT includes in the message it sends to the satellite. Much more accurate than triangulation.

Derek
 
I'd skip that particular unit. I've had at least three false activations, all while sitting on the ground and prior to any flight that day. It's an intermittent issue so near impossible to determine the cause.
 
Same here

FWIW, I think at least two of my false activations were caused by a balky panel switch.

I'd skip that particular unit. I've had at least three false activations, all while sitting on the ground and prior to any flight that day. It's an intermittent issue so near impossible to determine the cause.
 
I am looking to upgrade to a 406mHz ELT. The ACK E-04 unit says that it can interface with a Garmin GPS through a pair of RS-232 wires (plus a power and ground wire). My question is 'what is the benefit of this interface?'

I installed a new E-04 last month. The GPS interfacing looks simple, but checking that it is working (see page 9 install manual) didn't work for me - could not confirm whether the LED flashed or not. Also, fetching the GPS data from a device you would possibly/probably turn off as part of an emergency procedure (master off) obviously provides no benefit. So...even though I put myself through the ***-pain of interfacing the E-04 with my GRT SafeFly GPS, it's probably for nothing in the end.
 
I have two of those ELTs and never a single issue. Both are also interfaced to GPS's.
 
Have owned at least three with no issue. As far a turning off the GPS in an emergency, I do believe the ELT will transmit the last signal it had. Now if your on fire and able to fly a hundred miles that could be a problem. I could be wrong on the last signal.
 
ACK E-04

There's definitely nothing wrong with their performance once they are activated. On my third erroneous activation, the thing managed to transmit through a fully closed metal hangar. I assume it was using its last known position, as you note.

Have owned at least three with no issue. As far a turning off the GPS in an emergency, I do believe the ELT will transmit the last signal it had. Now if your on fire and able to fly a hundred miles that could be a problem. I could be wrong on the last signal.
 
I installed a new E-04 last month. The GPS interfacing looks simple, but checking that it is working (see page 9 install manual) didn't work for me - could not confirm whether the LED flashed or not.

That almost certainly means you didn't jumper the baud rate correctly or you are sending a GPS format it doesn't understand.

The safefly gps outputs the following by default:

Serial Port 1 Out 4800 baud, NMEA0183 pins 19,20
Serial Port 2 Out 9600 baud, NMEA0183 + RAIM pin 3
Serial Port 3 Out 115200 baud, NMEA0183 + RAIM pins 1,2

The E-04 inputs NMEA0183 at 9600 baud by default, which means it would only work on port 2 and only if the RAIM didn't cause issues. I'd probably connect it to port 1 and set the jumpers on the ELT to 4800 baud.

abuura said:
Also, fetching the GPS data from a device you would possibly/probably turn off as part of an emergency procedure (master off) obviously provides no benefit. So...even though I put myself through the ***-pain of interfacing the E-04 with my GRT SafeFly GPS, it's probably for nothing in the end.

The ELT will broadcast the last known GPS it got if the elt was activated. I'd probably not power down the master until just before impact which means that comsat will know your coordinates within a mile or less on the very first ping. I wouldn't say that's for nothing.

I recommend spending a little more time to sort through the issue so that you aren't depending on triangulation which could potentially shift rescue times by hours.
 
I was told by an elt manufacturer that the difference with gps was something like a couple dozen meters vs a couple hundred meters, so I chose to skip the hookup. I don't have that in writing though, so take it for what it's worth.

I had two inadvertent activations ( junk old Amerikings). The first time the elt was in my garage and the Air Force narrowed it down to my street address. To be fair, I live in a semi rural area. The second time they narrowed it down down to the airport.
 
You guys that have done it, do you wire the serial output in parallel to other devices? I have 1 puck for EFIS and 1 for ADSB. I’d like to share the output if possible.
 
I have 1 puck for GRT Safe Fly, I wired from the serial port 2 output to the ELT. I'm not sure what GPS and EFIS you have but you should be able to do something similar. Do you have any used serial outputs? You just have to have the correct baud rate.
 
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I was told by an elt manufacturer that the difference with gps was something like a couple dozen meters vs a couple hundred meters, so I chose to skip the hookup. I don't have that in writing though, so take it for what it's worth.

Per Civil Air Patrol, 406 beacon accuracy without GPS is on the order of 1-3 miles, versus a few hundred feet with GPS.

https://www.gocivilairpatrol.com/media/cms/Prosecuting_406_MHz_Distress_Beacon_DAE24A42EC69E.pdf

In general, the best part of the high accuracy is how quickly a false alarm can be run down. If you have the ELT in your house, armed, and it gets dropped (it happens), a ground team can go to the right city block and quickly figure out where it is. When the accuracy is miles, clearly it will take more effort.

Contrast this to the old 121 MHz beacons which virtually always required a plane to be launched to localize the signal. I had a case where airliners for LAX were reporting the signal, and we (aircrew) localized it to the Oxnard harbor - allowing a ground team to take it to the next step.

The halt in listening for 121 beacons (which were getting old and prone to going off when it rained), combined with the ease of finding 406's did in a lot of paid for search flights.
 
I installed a new E-04 last month. The GPS interfacing looks simple, but checking that it is working (see page 9 install manual) didn't work for me - could not confirm whether the LED flashed or not. Also, fetching the GPS data from a device you would possibly/probably turn off as part of an emergency procedure (master off) obviously provides no benefit. So...even though I put myself through the ***-pain of interfacing the E-04 with my GRT SafeFly GPS, it's probably for nothing in the end.

The LED light is hard to see the flash. Mine isn't bright and you need to look at the correct location on the light to see the flashes. You have to be outside to get a satellite pickup and that usually means bright sunlight. I troubleshooted for quite some time once trying to get a flash only to discover it was there all the time.
 
Does anyone have any feedback regarding this unit from Emerging Lifesaving Technologies? It uses a fairly large, unsightly blade antenna mounted on the tail cone.

My father originally installed this but I'm not sure I want to keep it. There's not a lot of information regarding this unit online. Their website isn't too impressive.

They spelled the name of their own company incorrectly at the bottom of the page under "About".

ELT GPS Antenna.jpg
 
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