View Full Version : ELT antenna mount

Bill Rusk
08-06-2006, 10:59 AM
Does anyone know if it is OK to mount the ELT antenna upside down?
The manual says within 20 degrees of vertical when in level flight and gives a bunch of other criteria but does not address this. Can vertical be upside down? Thanks


08-06-2006, 11:35 AM
Bill, i know i'm not answering your question -- but you got me thinking. I imagine you want to put the antenna in a place where it is least likely to be ripped off in an accident. I wonder if more accidents include flips or smashes

08-06-2006, 06:35 PM
Well a radio wave doesn’t know if an antenna is upside down or not. It shouldn’t matter so long as there is an adequate ground plane. For the 20 degrees I don’t know why they would state that. Would it be to eliminate an antenna sag/bend? Any ideas?

I don't know about up in AK or the far 'Nord' but down in the lower 48 there seem to be more belly landings/screw ups then flips. The terrain may be a BIG factor in that though...


08-06-2006, 06:42 PM
My brand new 406 ARTEX says to mount it on top of the fuselage in clear view of satellites. You make a good point about crashing right-side-up, although it also has a mandatory switch to be located in plain view of the pilot. I suppose their logic is to have us activate it as soon as things look bad, and hope the 406 satellite works as advertised with a near instant pickup.

08-06-2006, 07:50 PM
I mounted my ELT in the tail (I needed more tail weight)and the antenna inside the fuselage in back with a ty rap holding the whip from whiping around inside. Palhal

08-06-2006, 08:35 PM
Now, may I beg the question… If you hit something do you really want a whole bunch of people pawing around your plane? Sometimes an ELT isn’t an asset but rather a liability. A well operating unit can lead to the news media and Channel 5 helicopters. Just more problems.

A friend (I will not mention his name) was appointed in charge of training law enforcement individuals for airplane crashes. Naturally, he came out to our house as we seem to know a thing or two about accidents. Ahem, I mean incidents. No, correction, strategic tests of physics and gravity. Anyhow, he came out to the house and was absolutely hell bent on knowing where to cut the fuselage with the Jaws of Life if there is somebody inside. Also he wanted to know how long it took before the aircraft blew up. Just as the movies show ALL ACCIDENTS LEAD TO EXPLOSIONS. We all know that this fallacy simply is not true. IF I was in an aircraft and some adrenaline pumping dude with a badge came at my plane with the Jaws of Life, it would not be a good situation! My experience with situations such as this is when one does happen there is more damage done during the “rescue and recovery” then the initial accident.

To head it off, yes I do have a current and operational ELT in my planes. This does not mean I want the whole world knowing if I screw up.


mechanic mark
08-06-2006, 08:38 PM
when I started looking for an ELT for the jet, I called Artex and asked " If the antenna has to be within 15 degrees of vertical, what happens if I end up upside down."

There was a long pause. and he said what do you mean? upside down?

I explained that I knew of more then a few accidents where the top of the plane was not visible to the horizon.

I am still waiting for his reply. The 406 will not work without an antenna, so it won't do any good to remove the ELT afterwards. unless it also has 121.5 or maybe 24.6

Bill Rusk
08-07-2006, 06:39 PM
Called the manufacturer. Vertical is vertical. Upside down is OK.

Thanks for the replies.


Dave Calkins
08-07-2006, 07:27 PM
Guys, the Aviat Husky's have the ELT antenna mounted in in the tail.

They have a tab welded to one of the tubes between the lower longerons and the antenna is mounted to the tab.

The upper extended baggage (aluminum) is right above it and has no ill effects on the antenna radiation.

I like the idea.

Steve Pierce
08-07-2006, 08:10 PM
CAP found my Dad's airplane with the ELT going off in a metal hanger with the antenna in the tail. It must work pretty good.

08-07-2006, 08:10 PM

Is this for a 406 antenna, and would you mind sharing the manufacturer with us? I'd sure like to do the same thing with an ARTEX.

Bill Rusk
08-09-2006, 07:42 AM

It is an Ameri-King model AK-450. The antenna is the one that comes with the unit. If you visit their web site they state in the FAQ's section that it is OK to mount it inside a fabric aircraft, and when I called the company the tec rep said it could be mounted upside down as long as it was within 20 degrees of vertical when in level flight. Hope this helps.


08-09-2006, 08:16 AM
The new ARTEX aircraft mounted unit also transmits on 121.5, I believe.


Dave Calkins
08-09-2006, 01:56 PM
Yes, M, it does.

I just did one and when I plugged in the remote switch connection, the thing turned on (the g-switch position is ignored until the connector is plugged-in). 20 minutes later the local rescue squadron had me on the line wondering how the a/c was. I was in a closed hanger and the satellite picked it up. The 20 minute delay was from the owner (who got the first tele. call) looking up my number and reaching me.

Bill Rusk
08-19-2006, 05:45 PM
Just to close this post. Here is a picture of the mounting.



08-19-2006, 10:16 PM

08-20-2006, 08:22 AM
The instructions mention a 36" diameter ground plane. They do mention the possibility of using tin foil.

Bill, What covering system are you going to use? A system that uses "silver" (dope, polyfiber) won't work too well with the antenna on the inside. Kinda like metalizing the skin.

John Scott

Bill Rusk
08-20-2006, 02:51 PM
Well....according to the instructions you only have to do the ground plane if the antennae is mounted on a "non metallic" airplane, ie Glasair, longEZ etc. The instructions say it is OK to mount it inside a fabric covered airplane. There is no mention of restrictions due to surface coatings on the fabric.
I will be using the AirTec system which does not specifically use a silver primer coat.

Thanks for asking.