ELT going off

wings_level · February 19, 2019

So I got a call from the airport today. Apparently my elt was going off. I missed the phone call but when I called back the airport manger had went in and reset the elt and everything is fine for now. The plane has been in the hangar and not flown in a little over a week. The batteries were just replaced this last annual. Any ideas?

**amillet** · February 19, 2019

I got a similar call a few years ago. Went out to airport to check. Turns out it was an airplane two hangars away

**carusoam** · February 19, 2019

Any rough landings with that? Anything that would shake the sensor?

Best regards,

-a-

wings_level · February 19, 2019

9 minutes ago, carusoam said:

Any rough landings with that? Anything that would shake the sensor?

Best regards,

-a-

Nope. But even so, the plane has been sitting for well over a week. Seems like if there was a rough landing it would go off then or very shortly after.

**carusoam** · February 19, 2019

In the hangar, I was thinking the radio signals may not be getting very far, so somebody was finally able to report it...

How long do the batteries last? A day? So it has ‘t been going off all week...

Any hangar elves working over the weekend?

Sorry, that’s the best I could come up with...

Best regards,

-a-

GDGR · February 19, 2019

Alone in the hangar? Someone else have to move it by chance? AME here had one go off on him while towing one out of his shop.

wings_level · February 19, 2019

Yep. Alone in the hangar. Must be one of those weird flukes. Maybe it won’t go off again.

**PT20J** · February 19, 2019

An ELT is pretty unlikely to go off for no reason. Most likely scenario is that it was set off the last time you flew, and the hangar shielded it so that the signal was weak, and so it took a long time to find it. You didn't say what ELT you have but if it was a TSO-C91A ELT, the satellites haven't monitored its 121.5/243.0 MHz transmissions since 2009, so someone would have had to listening to 121.5 nearby to even notice it. Since you have no way of knowing how long it was transmitting, you'll have to replace the battery anyway and that would be a good time to have it checked out.

Steve W · February 19, 2019

Moisture, bad switch, etc. Plenty of random reasons. One of the the most common ones on the ramp going off was the plane that hadn't been touched in years and had a couple flat tires and was covered in dirt.

**PT20J** · February 19, 2019

Kind of like that master switch that keeps failing ON and running the battery down? Or the moisture that makes the the gear retract all by itself? Maybe ghosts?

February 19, 2019

6 hours ago, Steve W said:

Moisture, bad switch, etc. Plenty of random reasons. One of the the most common ones on the ramp going off was the plane that hadn't been touched in years and had a couple flat tires and was covered in dirt.

Quite likely, how many ELT’s in the US go to an avionics shop to be tested, versus given a smack by the A&P during the annual. In Canada we send our ELT’s out every year.

Clarence

**takair** · February 19, 2019

Hangar elves playing games? Mice? Lol

What kind of ElT do you have? Best have it checked and replace the batteries if it is ok otherwise.

Marauder · February 19, 2019

Quite likely, how many ELT’s in the US go to an avionics shop to be tested, versus given a smack by the A&P during the annual. In Canada we send our ELT’s out every year.
Clarence

What is interesting is that on about every third or fourth flight I make in the mid Atlantic, I will hear an ELT on 121.5. And it is usually not during the hourly ELT test time and certainly more than 3 sweeps.

Sent from my iPad using Tapatalk Pro

**PT20J** · February 19, 2019

Let's see if we can summarize:

ELTs have two problems: failure to activate in a crash, and high false activation rate. From an engineering standpoint, it is difficult to achieve both at low cost.

There are three generations of ELTs meeting TSO-C91, TSO-C91a and TSO-C126. Each generation has attempted to improve these parameters.

The failure to activate rate has improved; the false alarm rate has not (see Molnar 2005 - pg. 95 and InFO18007)

No one knows why some ELTs go off absent a crash. Most activations are thought to be mishandling, accidental activation or maintenance related. There is some evidence that first generation ELTs did suffer from switch and corrosion issues (Trundell 1990, Pg. 7-8). This data is suspect since it is unexplained how the failure mode was determined in each false alarm case. It may just be the reporter's best guess. If every falsely activated unit were returned to the manufacturer for analysis, then we might know something, but this is not generally done. TSO-C91 units have not been manufactured or legal for new installations since 1995, but there are probably a lot of them in the field.

So, what to do? An ELT that falsely activates when the cause is unknown should be considered unreliable. TSO-C91 and TSO-C91a units have not been monitored by satellites since 2009 and are of marginal SAR value and should be replaced with a TSO-C126 406MHz unit. A malfunctioning TSO-C126 unit should be returned to the manufacturer for analysis and repair. The minimum legal requirement per 91.207 in any case is to replace the battery if it has been activated for more than an hour.

Skip

InFO18007.pdf

Molnar 2005.pdf

Trudell 1990.pdf

**EricJ** · February 20, 2019

I had an ACK E-01 in my airplane when I bought it, and have since replaced it with an ACK E-04. The E-01 went off in turbulence once. I didn't think the turbulence was even all that bad, although it was rough, but it set off the ELT. The E-04 went off totally randomly once during takeoff. I noticed it while climbing out and reset it on crosswind before a downwind departure. I told the tower it had gone off and I'd reset it in case they cared.

Now I make it a habit to look at the little blinky light once in a while just to see whether it decided to turn on or not.

No idea what was up in either case, but they can do it sometimes.

David Lloyd · February 20, 2019

I've had several so-called landings where I was shocked my ELT did not activate.

M20F · February 20, 2019

On 2/19/2019 at 6:41 AM, M20Doc said:

Quite likely, how many ELT’s in the US go to an avionics shop to be tested, versus given a smack by the A&P during the annual. In Canada we send our ELT’s out every year.

Clarence

You have Polar Bears in Canada, hence the added caution.

**PT20J** · February 20, 2019

The G switch responds to longitudinal deceleration. Turbulence and hard landings generate (mostly) vertical accelerations.

**1964-M20E** · June 4, 2019

Well today while doing my annual the IA was looking a my Artex ELT345 (406mhz) and it started going off and we could not reset it. I finally disconnected the battery after talking with the avionics shop that installed it. I did receive a call from the Air Force checking up on me . I was expecting them to call and it was within about 1 hour of the ELT being activated.

ARTEX did not return any of my calls today or answer any other communications. Trying to get an RMA number to send it in. I would think that if you have one of their ELTs going off un-commanded and cannot reset it that the manufacturer would try to call you back pretty quickly.

My avionics ship said it is a know common occurrence for this to happen.

Has anyone else had this problem with an ELT345?

**1964-M20E** · June 5, 2019

I did get an email from ARTEX yesterday and filled out a couple of forms and sent them back. We will see where this goes from here.

**1964-M20E** · June 7, 2019

Sign In

ELT going off

Recommended Posts

wings_level

amillet

carusoam

wings_level

carusoam

GDGR

wings_level

PT20J

Steve W

PT20J

Guest

takair

Marauder

PT20J

EricJ

David Lloyd

M20F

PT20J

1964-M20E

1964-M20E

1964-M20E

philiplane

RobertGary1

amillet

1964-M20E

Join the conversation

Members Online

Browse

Activity

Important Information