ELT frequencies

[4RNB]

I am considering some international travel. My reading states ICAO requires elts the transmit on 121.5 and 406 mhz. How do I figure out if my elt qualifies? Are the frequencies published on data plates?

2009 vans rv10 if it matters, thumbing thru all the records without success so far. “Ameriking” is all I am seeing.

 

[donjohnston]

I installed the Artex ELT 1000.

ELT 1000 - ACR Electronics, Inc 406 MHz Emergency Locator Transmitter

The ELT is an automatic fixed emergency locator transmitter with a single antenna output for emergency transmission on both 406 mhz and 121 mhz frequencies. The Artex ELT 1000 is a value-priced upgrade for standard 121.5 mhz transmitters which are longer monitored by the Cospas-Sarsat system.

www.acrartex.com

the ELT 1000 transmits on 406 MHz and 121.5 MHz frequencies.

 

[Greg Bockelman]

I would think it would say on the ELT somewhere.

 

[4RNB]

It doesn’t but it does say ameriking ak450. My brief read of the Internet is this does not have 406 MHz on it. It seems like the 406 MHz rule went into effect the year. This plane went flying now I just need to find a replacement that’ll fit in that same bracket

 

[Craig]

The operating frequencies are listed right there, the third line from the bottom....121.5/243.0 MHZ. That unit doesn't cover the 406 Mhz frequency. I don't think there is a drop in replacement out there since AmeriKing lost their TSO's.

 

[unsafervguy]

i doubt you will find a unit that fits in that bracket. also, the way the bracket is mounted may or may not be legal for a 406 unit. there are stricter mounting requirements for a 406 unit than the 121 units had. they have to be mounted in a certain area, be mounted to structure, and have limits on how much they can move. because an elt is required to be a tso unit, even in an EAB, it must be installed according to the manufactures instructions and the TSO requirements.

 

[Jim Carpenter]

OP question already answered by Craig and the label picture.....and, further, do you have a cockpit on/off switch for the ELT? If not, I believe that's a requirement when upgrading to 406 MHz, not that big a deal in a small unpressurized airframe, but just one more thing.

 

[mondtster]

It doesn’t but it does say ameriking ak450. My brief read of the Internet is this does not have 406 MHz on it. It seems like the 406 MHz rule went into effect the year. This plane went flying now I just need to find a replacement that’ll fit in that same bracket

The AK-450s were 121.5 mHz only. They also have an AD against them that needs compliance.

The 406 mHz ELTs are a good upgrade and should be considered even in locations that don’t require them.

 

[Craig]

The AK-450s were 121.5 mHz only. They also have an AD against them that needs compliance.

Don't think there was ever an ELT made that was 121.5 only......Every one I've seen was 121.5/243.0. The ACK450 eve states on it's label that it transmits on 243.0. See the photo in post #4.

 

[Klaus M]

The AK-450s were 121.5 mHz only. They also have an AD against them that needs compliance.

The 406 mHz ELTs are a good upgrade and should be considered even in locations that don’t require them.

The A.D. 17-16-01 is required on all AK-450 and AK-451 ELTs (even homebuilts). A quick way to know the difference is "D-Cell" batteries or Lithium. The D-Cell battery ELT unit is 121.5/243.0.

Dynamic Regulatory System

drs.faa.gov

If you're flying international, then be sure to hook your new 406mhz ELT up to a GPS. The satellites will pick up your coordinates and find you a little faster.

 

[flyingron]

The operating frequencies are listed right there, the third line from the bottom....121.5/243.0 MHZ. That unit doesn't cover the 406 Mhz frequency. I don't think there is a drop in replacement out there since AmeriKing lost their TSO's.

Don't get me started on Ameriking. Yeah, that is a TSO 91a (as it says) unit and its no longer tracked by the satellites and the FAA bars you from putting those in other than replacing like kind. You need a TSO-C126a (aka 406MHz) unit. This not only uses a frequency tracked by the satellites, it has the provision to feed it a GPS location, and it has an ID to know what GPS is going off.

It's a relatively straight forward conversion. If you get an ACK unit, you may be able to reuse the remove wiring as AK ripped off the design from them.

 

[4RNB]

I'm trying to buy stuff for a first condition inspection so that the plane does not take up hangar space waiting on shipping.

 

[mondtster]

Don't think there was ever an ELT made that was 121.5 only......Every one I've seen was 121.5/243.0. The ACK450 eve states on it's label that it transmits on 243.0. See the photo in post #4.

Point taken, my only intent was to state it was not a 406 ELT.

 

[flyingron]

The C90 ELTs indeed did 121.5/243. It's a big sloppy, they're just crudely amplitude modulated and 243 is the second harmonic. They probably put out on 364.5 as well but at a reduced amplitude.

 

[Dan Thomas]

i doubt you will find a unit that fits in that bracket. also, the way the bracket is mounted may or may not be legal for a 406 unit. there are stricter mounting requirements for a 406 unit than the 121 units had. they have to be mounted in a certain area, be mounted to structure, and have limits on how much they can move. because an elt is required to be a tso unit, even in an EAB, it must be installed according to the manufactures instructions and the TSO requirements.

Yup. But I found too many 406s just screwed to the same place the 121.5 used to sit, and they did not meet any 406 rigidity and security requirements at all. If those requirements are not met, the unit may not trigger or could rip off and sever its antenna cable, and now you have a thousand-dollar totally useless lifesaver.

 

[Dan Thomas]

If you're flying international, then be sure to hook your new 406mhz ELT up to a GPS. The satellites will pick up your coordinates and find you a little faster.

That takes a 406 that has that provision. Costs more, and costs more to install.

 

[Clip4]

Thank you Congress for requiring a human remains recovery beacon in GA aircraft.

 

[Dan Thomas]

Thank you Congress for requiring a human remains recovery beacon in GA aircraft.

Well, when search and rescue costs can easily surpass a million bucks a day to find a lost GA airplane......

 

[donjohnston]

Yup. But I found too many 406s just screwed to the same place the 121.5 used to sit, and they did not meet any 406 rigidity and security requirements at all. If those requirements are not met, the unit may not trigger or could rip off and sever its antenna cable, and now you have a thousand-dollar totally useless lifesaver.

How do those requirements prevent an antenna from being ripped off when the aircraft flips over? I know a guy who waited 4 hours to be found just outside of Orlando because SAR couldn’t find him after his aircraft flipped over rendering his 406MHz ELT useless.

 

[Clip4]

Well, when search and rescue costs can easily surpass a million bucks a day to find a lost GA airplane......

It doesn’t cost any less with a failed ELT…..

The old ELTs have a failure rate in a crash of 75% and up to 20% for the 406s. The FCC wants all the old 121.5 units banned, but keeps extending that mandate.

 

[Dan Thomas]

The old ELTs have a failure rate in a crash of 75% and up to 20% for the 406s.

So 80% of downed aircraft have a working ELT to help find them. That's bad?

 

[Clip4]

So 80% of downed aircraft have a working ELT to help find them. That's bad?

No, 80% with a 406 activate upon the crash. That isn’t the same as working when they find the plane. If the plane crashes and 20 seconds later is destroyed by fire, it counts as an activation.

 

[Dan Thomas]

How do those requirements prevent an antenna from being ripped off when the aircraft flips over? I know a guy who waited 4 hours to be found just outside of Orlando because SAR couldn’t find him after his aircraft flipped over rendering his 406MHz ELT useless.

That's a problem, as is sinking or burning or being scattered across a half-mile of granite mountainside. There is no perfect ELT. The next generation needs to be based on SPOT technology where a location is broadcast to satellites every 15 seconds or so to establish a track, and the cessation of locations implies a downed aircraft. If MH370 had had such technology it might have been located long ago. Of course, the device would have to be inaccessible to the pilots in flight so that it could not be turned off.

 

[bflynn]

The C90 ELTs indeed did 121.5/243. It's a big sloppy, they're just crudely amplitude modulated and 243 is the second harmonic. They probably put out on 364.5 as well but at a reduced amplitude.

243 is the military guard frequency. It's their version of 121.5.

Modern 406 ELTs will still signal on 121.5 to assist with DF searching, say by CAP.

 

[Craig]

Factor this in...An ACK E04 with international programming is a special order item and no clue how long it takes to get shipped. Best thing would be to call ACK directly and ask.

 

[donjohnston]

That's a problem, as is sinking or burning or being scattered across a half-mile of granite mountainside. There is no perfect ELT. The next generation needs to be based on SPOT technology where a location is broadcast to satellites every 15 seconds or so to establish a track, and the cessation of locations implies a downed aircraft. If MH370 had had such technology it might have been located long ago. Of course, the device would have to be inaccessible to the pilots in flight so that it could not be turned off.

Correct. Which is why installing the ELT and antenna per the requirements will not prevent the antenna from being ripped off during a crash.

 

[geezer]

No system is failure free, but the most failure free is the system we should be using.

I have called ATC to report locater beacon received on guard, and they replied "That beacon is confirmed on an airport, thank you for monitoring guard".

 

[flyingron]

243 is the military guard frequency. It's their version of 121.5.

Modern 406 ELTs will still signal on 121.5 to assist with DF searching, say by CAP.

I understand that, but it was chosen to be the harmonic of 121.5 and older ELTs very much use that fact to their advantage.

A 406 has separate circuits to transmit on 121.5 and 406. The 121.5/243 is just designed to radiate on the harmonic.

 

[Dan Thomas]

Modern 406 ELTs will still signal on 121.5 to assist with DF searching, say by CAP.

Yup. The 121.5 is for final homing, using DF, by the searchers after the satellites have determined the general area to search.

The idea the satellites use to locate is the Doppler Effect. As a satellite approaches a signalling ELT, the ELT's carrier frequency appears to rise, just like a locomotive's horn blast appears to rise as it approaches the crossing. As the satellite passes overhead the ELT, that frequency stabilizes and then begins to fall as the satellite moves away. A couple of passes is usually enough to get a location of some accuracy. The 406 MHz signal offers better Doppler definition over the 121.5, reducing the search area considerably, but you're still faced with some square miles to search, so the 121.5 homing signal fixes that. Of course, a GPS location transmitted by the ELT is better, but in the mountains you could end up in some ravine where the sky is mostly obscured.

 

[Gilbert Buettner]

Thank you Congress for requiring a human remains recovery beacon in GA aircraft.

A couple of years ago we had a Bonanza crash short of the runway in foggy conditions. Within about one minute, the Air Force called the FBO and said they were picking up a ELT signal "on the airport." Folks in the office knew that the airplane had not landed, and had assumed it went missed. They drove out to look for the wreckage, and it took a while to find it OUTSIDE the airport fence, between the runway and a lake. He had gone below MDA and pulled up at the last second when he saw the shoreline. Trees stopped the airplane in short order.

The pilot had suffered a broken pelvis and several broken ribs. He dialed 911 and the local emergency folks searched for him about a quarter mile away, based on his cell signal. Airport personnel did find him first and got emergency medical help, and he survived. That might not have happened with anything other than a 406 MHz ELT.

 

[Gilbert Buettner]

Yup. The 121.5 is for final homing, using DF, by the searchers after the satellites have determined the general area to search.

See my post #30 above. The satellites apparently knew precisely where to search. They told us he crashed on airport property and that is where he was found.

If the CAP had been involved, he may have perished between the time of the crash and the time they could find a crew, an airplane, and get permission for the search.

 

[Pinecone]

The C90 ELTs indeed did 121.5/243. It's a big sloppy, they're just crudely amplitude modulated and 243 is the second harmonic. They probably put out on 364.5 as well but at a reduced amplitude.

The reason for 243.0 is that it is the UHF emergency frequency. And that is monitored by just about every military aircraft all the time. The standard military radio has a second receiver in it just for 243.0.

BTW, the military VHF FM emergency is 41.5