Audible ELT Signals

[SoCalCAPOfficer]

One of my Senior members asked a great question while in a ground school class where we were discussing ELT's.   She wanted to know why the ELT that is in the airplane does not also have an audible signal, such as like a fire alarm, go off as well as transmitting the 121.5 signal. 

Her contention was that with an audible signal the pilot would hear it if it was caused by a hard landing, and in any case it would make it a lot easier to find the plane on the ramp or in a hanger during an ELT search.

We thought about her question and really could not come up with a good reason why they are not so equipped.  One person thought it might be because it would run the battery down quicker.  However, if the audible signal device was like the ones in a home fire alarm, it would only need its own 9 volt battery.

Then someone suggested it would be to expensive to retrofit the existing ones with an alarm.  However, one of our radio people posed that a very inexpensive separate alarm could be made that would pick up the 121.5 signal if it went off withn a couple of feet of the device.  These could be after market units to be put in planes relatively inexpensively.

So my question is.  Are there devices like this available, and if not, why not?

[RiverAux]

Never heard of one.  Since the ELT is inside the body of the airplane, an audible alarm would probably not be terribly loud unless you mounted an external speaker.  Given that the simpler solution is for the pilot to check 121.5 after landing, it hardly seems worth it. 

[jeders]

Never heard of one.  Since the ELT is inside the body of the airplane, an audible alarm would probably not be terribly allowed unless you mounted an external speaker.  Given that the simpler solution is for the pilot to check 121.5 after landing, it hardly seems worth it. 

I think that's the real reason, if the pilot is doing a good job, he'll check 121.5 on his radios before shutting down. Plus, unless it was either a really loud speaker or mounted externally on the plane, you likely wouldn't hear it going off while you walk down the ramp.

[_]

Are there devices like this available, and if not, why not?

My smart butt response is that they don't have an audible alarm because that would make to much sense.  My guess as to the real reason is that these beacons are meant to go off in a crash and are designed that way.  If you're in a crash an audible sound from the ELT probably wouldn't really do any good to the pilot.  Having an audible sound would help us but the elt's aren't made to help us.  Plus it isn't required so a company isn't going to spend extra money on extra parts that aren't required and a pilot wouldn't care to have.

[♠SARKID♠]

Some of the new 406's do have an audible beep.  Sometime last spring/summer my squadron had a mission down at  Mitchell International Airfield, Milwaukee.  They were tracking a 406 and as they went down the ramp, they kept hearing a beep every 15 seconds or so.  They eventually found out it was coming from the 406 they were tracking.  It couldn't be heard from very far away, at least 30 ft, but it was there.  Makes a lot of sense: if a maintanance man hears the beeping, he'll know that the beacon is going off even though he isnt constantly monitoring 121.5.

Now, how does that relate to a crash?  Not much.

[_]

Now, how does that relate to a crash?  Not much.

That's probably a direct result of having so many false alarms.  When the first ELT's were created there wasn't an expectation of so many false alarms.  When they were redesigned from the bottom up someone probably saw what's been going on with the old generation of ELT's and included this feature.

[SoCalCAPOfficer]

If any of you have ever heard a home fire alarm going off, it will get your attention.
I had one go off in my garage last month in a box of junk and I heard it in the house which is over 200 ft away.

The audible signal would not help in a crash much.  However, it would make our lives easier and get the pilots attention to shut it off before he has to replace the battery. In a perfect world all pilots would check 121.5 before shutting down.  However the number of ELT's going off at airports show it is far from a perfect world.  I'll bet this device could be made for around $20.00. 

[lordmonar]

An audible alarm would eat up battery time.

As it is you only get about 24 hours or so on the ELT as it is....adding an alarm would cut that margin down greatly.

[SoCalCAPOfficer]

An audible alarm would eat up battery time.

As it is you only get about 24 hours or so on the ELT as it is....adding an alarm would cut that margin down greatly.

No what we are proposing is a separate unit run off a nine volt battery, just the same as a home fire alarm.  It would not use the ELT'S battery.

[_]

As it is you only get about 24 hours or so on the ELT as it is

You can get several days if not a week from an ELT battery

[Brad]

Well at first I thought this was an example of an audible ELT setup, but then I realized that it's only heard while 121.5 is tuned.

Regardless though, here's an ELT setup in an aircraft for everyone to test out.

http://flightlink.com/vts/demos/ELT.html

[RiverAux]

If it was a separate unit, it would not help us with the significant percentage of ELT missions relating to ELTs that actually aren't in the airplanes anymore. 

[SoCalCAPOfficer]

If it was a separate unit, it would not help us with the significant percentage of ELT missions relating to ELTs that actually aren't in the airplanes anymore. 

I know there are a percentage that are not in the airplanes anymore, however, every ELT I have ever found was either in the airplane or within a few feet of the airplane on the bench.   This would take care of those instances which are caused by a hard landing or someone bumping the airplane hard, or accidently setting it off while working on the airplane.   Those are the majority.

[♠SARKID♠]

Well at first I thought this was an example of an audible ELT setup, but then I realized that it's only heard while 121.5 is tuned.

Regardless though, here's an ELT setup in an aircraft for everyone to test out.

http://flightlink.com/vts/demos/ELT.html

Well now, thats a neat little doohickamabob...

[afgeo4]

So why not design one?

If you have a good idea, make it happen!

[SoCalCAPOfficer]

That was the point of this thread.  To find out if CAP people thought it was a good idea.  The results so far are a little disappointing. 

[BigMojo]

This may sound really petty...but if I were in an actual off-field emergency landing, or my boat sunk, the last thing I'd want to hear is the ELT "woop" for hours on end, or a smoke detector sound, or beep, or whatever...It would drive me to impale the ELT on the nearest sharp object. (Remember, when in an emergency situation you aren't necessarily thinking clear enough to think to cut speaker wires). If I see the strobe working, that's all I need to know that help is on the way. Any audible alert needs a manual off switch.

I think I have the credentials to say this, as I have been on a 31' foot boat that started taking on water and capsized 20 miles off the S. Florida coast at night, and have used an EPIRB in an emergency situation. Coasties were on scene in 1 hour with a helicopter, and the cutter was a half-hour behind. EPIRB saved us, but if I had to hear an alarm for an hour in that deafening silence, I would have gone nuts.

[floridacyclist]

The ease which which the already-functioning warp tone could be fed to a small audio amp powered by a seperate battery would have made this a no-brainer if any of us had mentioned it to the right people years ago, especially EPIRB manufacturers. Most boaters aren't as perfect as pilots and rarely if ever check 121.5 after going fishing...the audible tone that we hear over the radio would be a perfect way to notify him that his wife accidentally turned the unit on while cleaning the boat (real story) or to let the West Marine salesperson know that a customer turned a unit on before putting it back in the box (yet another real story).

[BigMojo]

I don't know a single boater that checks 121.5... Marine Band radios aren't equipped to hear that frequency, and I don't know anyone that carries a scanner or other device to hear it. A small speaker would be good, as long as it can be switched off (IMHO). I think it would drop the number of accidental activations to near 0.

[Brad]

http://www.faa.gov/airports_airtraffic/air_traffic/publications/ATpubs/AIM/Chap6/aim0602.html


A rather interesting read, I poured over it while killing time before work this afternoon.

I'm familiar with a good chunk of it, i.e. squawking 7700, 7600, or the dreaded 7500 (hijacking).

Going back again to VATSIM, I've worked a few 7700 situations from both behind the scope and behind the yoke. (Yea, bringing in an Embraer 190 on visual approach at night at KJFK with no instrument display after an alt-tab borked up my screen = NOT FUN!)