243.0000 MHz

[Saint]

Just herd traffic on 243.0000 MHz, went like this,
Cleveland center 968, Radio Check, he said this twice and finally got a response, the second time he said ON guard. could not hear the audio to who he was talking too.
Any information on this.
968 sounded like he was in my living room he was so loud and clear.
Steve
Fort Erie Ontario Canada

 

[N1BHH]

He was probably flying over your head. Sounds like they might have lost contact on another frequency, or simply testing their guard radio. 243.0 is guard.

 

[Saint]

Guard

He was probably flying over your head. Sounds like they might have lost contact on another frequency, or simply testing their guard radio. 243.0 is guard.

So this could be any aircraft, military or commercial, or private, I tried to find who is 968 but no luck, my thought was it's military.
Steve

 

[ka3jjz]

243.0 is the mil equivalent of the guard freq of 121.5. Nominally reserved for emergencies only, I've heard numerous folks on the 121.5 side 'radio checks' only to find out that someone is listening, and none sounded too happy they're using the freq like a CB channel. Around here (central Maryland) if someone violates a no-fly defense zone (like around Camp David) a controller might try to contact the aircraft on 121.5 Woe be to him who ignores the warnings....73s Mike

 

[morfis]

Bear in mind that the guard freqs are band-boxed so it is possible to hear both military and civil traffic on the UHF guard freq

 

[eorange]

Nice catch!

Who exactly is listening on the other end of 121.5/243.0? Is it the ARTCCs?

 

[Saint]

Guard

:lol: Thanks so much for all the information on this subject, I don't know to much about Guard and 243.0000 MHz, it's the first time to catch anything on this emergence frequency down hear. I have a old scanner I just use for the emergency frequencies hear in Canada and the US so it's only dedicated to Military and US Coast Guard Search and rescue.
Steve

 

[DaveNF2G]

Bear in mind that the guard freqs are band-boxed so it is possible to hear both military and civil traffic on the UHF guard freq

I think that depends on where you are. Not all facilities have this capability - or use it full time.

 

[Mainsail]

If I recall correctly, any transmission on guard freqs longer than 15 seconds will activate the S&R satellites.

 

[Yokoshibu]

As mentioned before not all facilities have the ability to simulcast on 121.5 and 243 ... Both are often referred to as "guard". Usually civilian traffic stays on the VHF spectrum so it is hard for a artcc, tower,.. etc.,etc. to check the UHF 243 so when a military aircraft is in their control they will usually request the aircraft to do a radio check on 243.

Why 243? what is 121.5 X 2 ? 243 of course. The logic for this is that the wavelength for 121.5 is so long that the antenna on an elt will sometimes bleed over to 243 because the antenna is usually a 1/4 wave or less on 121.5... this tends to make the antenna resonate on 243 (of course this depends on the specific length of the antenna and quality of the transmitter)

After sept 11 it became mandatory to monitor 121.5 if you had the capability eg spare radio. (better pilots were already doing that) This is one of the reasons why gaurd is more active with accidental transmissions.

This is a good thing as the sarsat's are going to be decomissioned and the coast guard has already posted a message that says they will (if they havent already) stop supporting epirbs OBTW the majority of the older epribs run on 121.5 / 243...

 

[CORN]

Bear in mind that the guard freqs are band-boxed so it is possible to hear both military and civil traffic on the UHF guard freq

Negative. You may hear simulcasting from the ARTCC or local controller monitoring both frequencies but you won't hear a civil aircraft on the UHF 243.0 freq. 121.5 only. I've heard numerous civil aircraft that lost their last freq check in with ATC on 121.5 to get the right one. 243.0 was silent. There's a lot of older military aircraft (F-15C for example) that used to be old school and were UHF only. Now with post 9-11 and it being imperative to talk to civil aircraft on 121.5 so a lot of the old school fighters are now equipped with VHF as well even though during normal ops they prefer to use UHF.

However, when an ELT goes off either military or civilian, it's siren will appear on both "guard" frequencies, 121.5/243.0 I've tried it with my scanner and a mechanic at work working with an ELT that was being checked out. Kind of neat.

 

[eorange]

However, when an ELT goes off either military or civilian, it's siren will appear on both "guard" frequencies, 121.5/243.0 I've tried it with my scanner and a mechanic at work working with an ELT that was being checked out. Kind of neat.

True that. I was at Field Day near Burke Lakefront airport in Cleveland, when a helo made a hard bounce landing. No one was injured, but they had to take the helo away on a flatbed. The ELT was bleeping for 1-2 hours after that! Heard it on 121.5, and that was the first and only time since I've ever heard traffic on 243.0.