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Thread: ELT Thought

  1. #1
    Senior Member 109JB's Avatar
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    Default ELT Thought

    So first of all, this is for my newly acquired project with fabric on and access a bit limited due to that. The airplane has an old but working 121.5 MHz ACK ELT where the builder put the antenna through the skylight. I have to replace the windshield and I would rather not do that if possible. On my other project I installed a mount and have the antenna internal to the fuselage based on reports of others. That said I was hooking up the handheld radio that i am going to use in this airplane and thought about the rubber ducky antenna that came with the handheld. I have an external antenna for the handheld and won't be using it. Being an antenna for a handheld aviation radio it is appropriate for 121.5 MHz although not perfectly tuned, and I was thinking I could just put it on the BNC connector on the ELT and internal antenna done. Any thoughts?
    John Brannen
    Morris, IL
    Sonerai IIL (Single Seat)
    Kitfox 3/4 1050 - Rotax 582 (Back Flying and sold)
    Kitfox IV 1050 - Rotax 582 (sold)
    Kitfox IV 1200 Speedster - Rotax 912 UL (project)
    Piper Twin Comanche (Sold)
    Glasair 1 FT (Waiting to start)

  2. #2
    Senior Member efwd's Avatar
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    Default Re: ELT Thought

    Hopefully your giving consideration to the fact this is a LIFE SAVING device. Under the circumstance, I would contact the ELT manufacturer or maybe you already know what they would recommend.
    Eddie Forward
    Flying
    SS7, 912iS, Garmin G3X

  3. #3
    Senior Member PapuaPilot's Avatar
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    Default Re: ELT Thought

    I will put on my A&P-IA hat for this one.

    For an ELT you need to use the antenna that came with that ELT or one that is approved by the manufacturer. Mounting it inside the fuselage is okay.
    Phil Nelson
    A&P-IA, Maintenance Instructor
    KF 5 Outback, Cont. IO-240
    Flying since 2016

  4. #4
    Senior Member 109JB's Avatar
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    Default Re: ELT Thought

    Not strictly true. Although that is the guaranteed way to meet the TSO requirements, even the installation manual for the ACK E-01 ELT in question states that other antennas can be used other than theirs:

    "Other antennas may be used provided they meet the VSWR requirements as noted in the specifications section of this manual..."

    I will get out the antenna analyzer and see how good/bad the ducky is.
    John Brannen
    Morris, IL
    Sonerai IIL (Single Seat)
    Kitfox 3/4 1050 - Rotax 582 (Back Flying and sold)
    Kitfox IV 1050 - Rotax 582 (sold)
    Kitfox IV 1200 Speedster - Rotax 912 UL (project)
    Piper Twin Comanche (Sold)
    Glasair 1 FT (Waiting to start)

  5. #5
    Senior Member PapuaPilot's Avatar
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    Default Re: ELT Thought

    Hmm, I will meet you halfway on that.

    Quote Originally Posted by PapuaPilot View Post
    For an ELT you need to use the antenna that came with that ELT or one that is approved by the manufacturer. Mounting it inside the fuselage is okay.
    Phil Nelson
    A&P-IA, Maintenance Instructor
    KF 5 Outback, Cont. IO-240
    Flying since 2016

  6. #6
    Senior Member 109JB's Avatar
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    Default Re: ELT Thought

    As far as a TSO-C91a ELT being a life saving device even with the manufacturer's antenna, personal experience as an NSTB investigator tells me that they aren't very good at saving lives. As a matter of fact, the frequencies used by C91 and C91a ELTS are no longer monitored by satellite and only 406MHz ELTs are monitored by satellite today. So if your legal C91 ELT activates it will have to be picked up by ground based pretty much line of site antennas to do any good.

    Now a TSO-C126 ELT is a different story. The 406 MHz signal is monitored by satellite and if you have one that either has an internal GPS or hooked to a GPS, then not only does the satellite hear it but knows where you are at almost instantly.

    Personally, I would trust a SPOT device more to save my life than a TSO-C91a ELT

    In this case the airplane is in flat corn country of northern Illinois, so rough terrain isn't an issue here anyway. The ELT is still legal, so it will stay at least until the airplane flies again. I may then think about getting a 406 ELT.
    John Brannen
    Morris, IL
    Sonerai IIL (Single Seat)
    Kitfox 3/4 1050 - Rotax 582 (Back Flying and sold)
    Kitfox IV 1050 - Rotax 582 (sold)
    Kitfox IV 1200 Speedster - Rotax 912 UL (project)
    Piper Twin Comanche (Sold)
    Glasair 1 FT (Waiting to start)

  7. #7
    Senior Member PapuaPilot's Avatar
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    Default Re: ELT Thought

    I totally agree with you on that. Most of the saves these days are from ADSB-Out, not the 406 ELTS. There are still way to many false activations of the 406 ELTs.

    installing a 406 ELT was a given when I was starting building my KF 8 years ago, especially since I live in Idaho and often go in the backcountry.
    Phil Nelson
    A&P-IA, Maintenance Instructor
    KF 5 Outback, Cont. IO-240
    Flying since 2016

  8. #8
    Senior Member efwd's Avatar
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    Default Re: ELT Thought

    "Personally, I would trust a SPOT device more to save my life than a TSO-C91a ELT"

    Kind of how I justified the cost of my Garmin InReach I bought for my Oshkosh trip. In spite of having a dual channel ELT with GPS.





    Eddie Forward
    Flying
    SS7, 912iS, Garmin G3X

  9. #9
    Senior Member Eric Page's Avatar
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    Default Re: ELT Thought

    There are at least two problems with relying on a portable satellite communication device (SPOT, InReach, etc.) to work as an emergency beacon. The first is that you may not be capable of activating it after a crash, and the second is that it may not be within reach once the aircraft comes to rest.
    Eric Page
    Building: Kitfox 5 Safari | Rotax 912iS | Dynon HDX
    Member: EAA Lifetime, AOPA, ALPA
    ATP: AMEL | Comm: ASEL, Glider | ATCS: CTO
    Map of Landings

  10. #10
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    Default Re: ELT Thought

    Quote Originally Posted by Eric Page View Post
    There are at least two problems with relying on a portable satellite communication device (SPOT, InReach, etc.) to work as an emergency beacon. The first is that you may not be capable of activating it after a crash, and the second is that it may not be within reach once the aircraft comes to rest.
    That's not how you typically use them. I fire it up and leave it running. It leaves bread crumbs every 10 seconds which show lat/long, altitude and velocity. Mine is an older DeLorme Inreach from before they were consumed by Garmin and will still run for about 72 hours on a charge.

    The thing it does which no ELT will do is allow you to send and receive text messages. There are canned messages but you can say anything.

    If I crash somewhere and I'm still alive I can use the SOS feature and summon help and still communicate. That may be what you're thinking about. In my case my significant other stalks me and would notice if my string of dots stops moving (and believe me, on the motorcycle that only takes her about 10 minutes).
    InReach track.jpg
    Of course I would never be doing 86mph on a public road, so there must be something wrong there.
    Last edited by alexM; 10-14-2021 at 06:20 PM.
    Kitfox 5 (under construction)
    Commercial SE/ME, CFII

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