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-   -   What ELT (https://vansairforce.net/community/showthread.php?t=140260)

JonJay 07-28-2016 11:17 AM

Quote:

Originally Posted by bret (Post 1098564)
It looks like the G trigger is in the forward direction, thinking about mounting in the spot designated in the plans behind the baggage wall, upside down but still forward arranged forward, and then install a Lexan window on the bottom of the fuse, in case a crash and end up upside down, and the external antenna gets damaged or coax severed, the internal GPS antenna can see the sky and yell for HELP? YES-NO? any other thoughts-ideas?

Careful. That is a structural area.
Last year, a young girl walked out of the woods here in Washington State. Her grandparents didn't make it out of the crash. The ELT didn't do anything. This was a certified Bonanza.
Your thought process is good, but you can not plan for every accident scenario.
I do not know why the ELT didn't work. Could have been a maintenance issue for all I know.

BobTurner 07-28-2016 12:18 PM

Quote:

Originally Posted by bret (Post 1098564)
It looks like the G trigger is in the forward direction, thinking about mounting in the spot designated in the plans behind the baggage wall, upside down but still forward arranged forward, and then install a Lexan window on the bottom of the fuse, in case a crash and end up upside down, and the external antenna gets damaged or coax severed, the internal GPS antenna can see the sky and yell for HELP? YES-NO? any other thoughts-ideas?

The g trigger looks for sudden decelleration in the forward AND vertical directions. Do not mount it upside down.

bret 07-28-2016 12:53 PM

Quote:

Originally Posted by BobTurner (Post 1098587)
The g trigger looks for sudden decelleration in the forward AND vertical directions. Do not mount it upside down.

Ok, thanks Bob. Any suggestions for where to mount one of theses so we have an open RF window for the internal GPS antenna?

BobTurner 07-28-2016 04:13 PM

Quote:

Originally Posted by bret (Post 1098596)
Ok, thanks Bob. Any suggestions for where to mount one of theses so we have an open RF window for the internal GPS antenna?

This is a lot harder than you imagine. It's not the GHz gps signal, it's the ELT signal that has an issue. A hole tends to look like a hole to radio waves only if the antenna is very close to the hole, or the hole is a lot larger than a wavelength. At 450 MHz a wavelength is roughly 2 feet. I doubt you're going to cut a 2 foot hole anywhere!

rzbill 07-28-2016 06:05 PM

As a one off that is different than all the other 406 units I am aware of, I installed an EBC-406 in the cabin of my 7A. No GPS, no annunciator panel (none required), I can activate it manually if needed and I can pick it up and take it with me if desired (assuming I could walk at that time :rolleyes:).

RV7A Flyer 07-28-2016 11:58 PM

Quote:

Originally Posted by Canadian_JOY (Post 1098521)
RV7A Flyer wrote:
"So what's the difference between a 406 MHz ELT and a PLB, really? Essentially, only the automation of initiating a signal, right? They're both GPS-based, satellite-detected, and initiate S&R immediately upon receipt of first signal, IIRC."

A couple of points of education here, if I may...

1) neither ELT nor PLB are GPS-based. they can both use GPS position to narrow the search area, but the primary means of location remains the production of a small search area through multiple passes of LEO satellites (soon to be MEO satellites), using Doppler, to locate the transmitter. If that transmitter is sending GPS information then that GPS position is provided to SAR via a geostationary satellite and virtually eliminates the need for multiple LEO satellites, thus giving SAR your position within minutes.

But since my PLB *does* use GPS, and it's unlikely that many would install a 406 ELT without hooking up a GPS if it's possible given their on-board GPS equipment, then in the real world, we're talking GPS location for the most part, with multiple sat passes as a sort of back-up.

Quote:

2) 121.5 ELTs are NOT satellite detected, and haven't been for several years. If your 121.5 ELT goes off, you're reliant on an over-flying aircraft hearing your transmission, then finding the transmitter is done by brute-force searching with airplanes and people. There is no way to take even a rough position hack off your 121.5 transmission - that died when the last 121.5 satellite splashed down in the ocean. Again, 121.5 ELT signals are NOT monitored by COSPAS-SARSAT, period.
I know that. I never said they were monitored or detected by satellite.

Quote:

3) a 121.5 ELT + a PLB does NOT = redundancy. A 406 ELT + a PLB = redundancy. Again, no big brother up in the heavens is looking for your 121.5 signal. A 121.5 ELT signal does NOT initiate SAR unless somebody just happens to hear it. Do you want to take the chance that you're unconscious, bleeding out, with your PLB hanging dormant on your harness? Think about it!
Which is why I said "activate the PLB as part of the emergency checklist".

I'm not averse to 406 ELTs...just their cost. If the price differential hadn't been so high, and the PLB gives me sat-based SAR *and* portability *and* low cost, then I might have installed a 406 instead of a 121.5.

But I didn't.

bret 07-29-2016 07:48 AM

Thanks for all the input gents, the one comment that hit me was (do you have life ins, do you want your family to get paid, they need to find you) that statement hit home for me, Just ordered the Kannad 11-09927 right now untill 8/2015 they have a free battery and retro kit offer, so there ya go.........Cha Ching! man this is getting expensive!...... :rolleyes:

moosepileit 07-29-2016 08:40 AM

Airlines have to monitor 121.5. I've relayed for distressed GA planes twice. We let ATC know when we here an ELT, sometimes false alarms sound for multiple days, which gets annoying and a bit disconcerting. CAP still sweeps and homes on 121.5, if not also 243. You can see them practicing at Oshkosh, the 4 antenna H pattern on a stick with a sunburned kid on the back of a golf cart, I think they practice on 121.6, based on a time the trainer hid one in our C-17 airshow static where one might want to play hide and seek.

Military monitors 243 in flight, typically. I have homed on activated parachute pingers overflying bases and radioed command post to let the life support shop know one needs to be tuned off. I have heard the new ELTs with GPS feeds, the data goes out on 406 and a synthesized voice on 121.5. I sent the lat lon to FSS, who then asked me about signal strength off some outdated checklist (false alarm at a home, but under a thunderstorm, I had started a 100 mile divert, realized I could not make it to the coords, found out later it was a false alarm). The folks that have to monitor 121.5 are probably wondering if I'm a "Guard Nazi" - I am not, it's sad to me how 121.5 is misuesed, and the 2x I've used it to aid have been filled with other pilots saying, "You're on Guard", causing missed calls to and from the distressed.

This is in only 6000 hours over 20 years of mil heavies and airlines. I'm probably typical.

Not to oversell outdated and not officially monitored ELTs. My issue is a basic fear of antenna function after a crash of any ELT. I believe I have a good chance of triggering the remote pre impact if off airport. The same thoughts on activating a PLB.

A 406/121.5/243 ELT with a dedicated gps feed is the current highest standard. Many good units do not have a 243 option. They still should be fine. Most of us have enough gps sources to feed an ELT's input without needing a 406 ELT with the GPS chip and antennae on the unit itself.


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