Mystery ELT Alarm on Startup

[Jeff_S]

Here's a weird one for the sleuths out there:

The Setup: 2007 Ovation3 with G1000 panel. So hitting the Master switch turns on everything.  Time was 9:15 am ET.

The Issue:  When I hit the Master button this morning, the radios came on and after a couple of seconds I started hearing what sounded all the world like an ELT alarm.  No other alarms in the panel or in the Alert box...just an ELT alarm coming from somewhere.  So I turned off the Master, waited a few seconds, then turned it on again.  Same thing. I (after searching for it a little bit!) activated my own ELT briefly and it did sound off, but turning that off didn't alleviate the original alarm.  So I shut down again, spent a few minutes looking for anything relevant in the manual (nothing found), and then gave it the old third college try.  This time the alarm did sound briefly but stopped after just a few more seconds.  So I had a normal flight, fueled up at the farm, and still no problem on restart to taxi back to the hangar.

The Mystery:  I was not tuned to Guard (121.5) on either radio, and I can't be sure where the alarm was coming from.  Was it from my own panel, or coming in somehow over the radio? At that point in startup I wasn't wearing my headset but the radio outputs over the speaker so that wouldn't matter. I didn't think to adjust the radio volume to see if that changed anything.  A buddy was doing runup at about this time and he did say he heard some ELT alarms briefly but he could have been hearing my short little tests. I'm not aware of any other audible alarm in a G1000 that would sound like this, and at any rate, it would certainly be paired with a text Alert in the Alert box.

So I'm open to theories, hypotheses or downright speculation!  Has anyone ever had something like this happen before?

[PeteMc]

What radios?  Do they power up to 121.5 and then switch to whatever was in memory from your last flight.

And what time of day?  Possibly right after the top of the hour and someone near by was testing their ELT.  Then they turned it off. 

 

[buddy]

I’ve had that happen to me a few times when turning on my master and I have a G1000 but it stopped within a few seconds. Since it only happened a few times in the past 10 yrs I never looked into it.