why 406 beacons are bad

[Buzz]

The 406's still signal on 121.5.....that has not changed.....the only difference is the power out up and how far you can receive it.

That difference is a MAJOR change, and it was UNNECESSARY.

The technological advances of the new ELTs are all "ahead" of the transmitter, and could have been paired with a 121.5 transmitter just as easily as pairing them with a 406 transmitter.  This one change would have ENHANCED capability, rather than reducing it.  Unfortunately for the people who will die because of that lost capability, some bureaucrat who has never been on a search for anything other than lobbyist gifts, and thinks that a "ground team" are the guys who mow his lawn, has decided how things are supposed to be done.

[Buzz]

Slightly Off Topic, but how many of you pilots out there monitor 121.5 when you fly?

Unless I need to talk to someone else, my radio is set to 121.5 because if _I_ ever need it, I don't want to have to dial it in.  I fly over an awful lot of empty desert when I'm on the mainland, and a lot of open water when I'm in Hawai'i.

I also have 121.5 as a priority monitor frequency on my scanner and on every ham rig I have that will receive it.

Back when I was growing up, the guy that taught my dad to fly ingrained this into him, asking "if you don't listen for the guy who needs you, who's going to listen for you?"

[davidsinn]

The 406's still signal on 121.5.....that has not changed.....the only difference is the power out up and how far you can receive it.

That difference is a MAJOR change, and it was UNNECESSARY.

The technological advances of the new ELTs are all "ahead" of the transmitter, and could have been paired with a 121.5 transmitter just as easily as pairing them with a 406 transmitter.  This one change would have ENHANCED capability, rather than reducing it.  Unfortunately for the people who will die because of that lost capability, some bureaucrat who has never been on a search for anything other than lobbyist gifts, and thinks that a "ground team" are the guys who mow his lawn, has decided how things are supposed to be done.

You can't transmit the data that 406's transmit on 121.5 because that is primarily a voice channel. No matter what you did you would have had to pick up a second channel to transmit the extra data.

[lordmonar]

The 406's still signal on 121.5.....that has not changed.....the only difference is the power out up and how far you can receive it.

That difference is a MAJOR change, and it was UNNECESSARY.

The technological advances of the new ELTs are all "ahead" of the transmitter, and could have been paired with a 121.5 transmitter just as easily as pairing them with a 406 transmitter.  This one change would have ENHANCED capability, rather than reducing it.  Unfortunately for the people who will die because of that lost capability, some bureaucrat who has never been on a search for anything other than lobbyist gifts, and thinks that a "ground team" are the guys who mow his lawn, has decided how things are supposed to be done.

We have not lost any capability.
The idea of going to 406 AND 121.5 is so the packet information going to the satellite is on a different freq then the GUARD voice chanel and the DF channel.

I suggest you go to the COPAS-SARSAT web page...and you will see the amount of engineering and thought went into this.

406 is better....BETTER then 121 on all accounts.....except price.

[Buzz]

You can't transmit the data that 406's transmit on 121.5 because that is primarily a voice channel. No matter what you did you would have had to pick up a second channel to transmit the extra data.

Nope, sorry, wrong answer.

A radio frequency is a radio frequency.  The only thing that changes is the payload.  APRS is digital data over a "voice channel."  Our P25 radios send digital data over "voice channels."  MODAT (the "burble-burble" ID code heard on a lot of public-safety systems) is digital data over a "voice channel."  All of the information sent by the beacon fits into a frame a fraction of a second in length, and could be sent during a periodic interruption in the ELT beacon squeal.  Since the bandwidth for data is narrower than for voice, it could even be sent on one side of the waveform, with the beacon running on the other, modulated BELOW the noise floor (as GPS does) to extend battery life.

If you have the advanced receiver, it will decode the data.  If you don't, you still have the beacon on 121.5, audible for miles and miles, with a half-second burst of data every ten seconds.  This means that existing equipment would still work as well as it ever has, and new equipment would have new features.

The 406 plan means that ONLY new equipment can be used for actually SEARCHING, with older equipment being used for pinpointing a target which as already been isolated to a small area. 

[Buzz]

We have not lost any capability.

Incorrect, Your Lordship.  A weaker signal on 121.5 means that our 121.5 equipment loses a lot of range.  We have lost the capability to pick up a signal on our existing equipment until we are much closer.  The ELT of today puts out a signal that can be picked up -- with a density sufficient for Doppler homing -- as far as 100 miles away.  The new one has a reliable radius of approximately 6.5 miles.  Doing the math, that means we've lost about 93% of our capability.

The idea of going to 406 AND 121.5 is so the packet information going to the satellite is on a different freq then the GUARD voice chanel and the DF channel.

And this does exactly NOTHING to help us.  A half-second burst of data, every 10 - 30 seconds?  What kind of problem would that pose on 121.5?  It could even be put in the head of every tone sweep, once per second, and not be in our way in the slightest.

The reason that this was done was because some fool arbitrarily decided that all emergency location was to be done on 406, rather than spending the $100 per satellite ($5 for the circuit, $95 to boost the extra two ounces to orbit) to put decoders on 121.5 and 243.0.

[lordmonar]

One reason for the freq change was so that ALL emergency beacons (marine, ground and aviation) were on the same frequency.
But your argument is kind of lame.

Even if they stuck with 121.5 as the only freq....then you would still have to buy new equipment.  Including DFers to process the digital encoded information.

End state.......exactly what we got now.  SAR agencies still needing to buy new equipment and pilots still having to buy new equipment.

Now here is the kicker.....

Unless you are an Airliner......no one is making you buy any new equipment.  AOPA successfully fought that.   

The 406's 121.5 signal is still audible for miles and miles.........just less then the old ELTs....the existing equipment STILL works.  Nothing in that respect has changed.....you can still do DF with the old Aircraft ELPER, still use VHF RDF equipment, still use wing masking....on the ground the old blue ELPER and the new orange ELPER still work.  You can still DF it with body masking.  None of that has changed.....you just have to be closer.....which the 406 signals does for you.......15KM closer and 3-4+ hours faster!......and if/when you do get the call you will not be out looking for some carrier only signal that turns out to be some defective TV tuner or a USB hard drive......because of the digital encoding.  So less false alarms, less wild goose chases for an ELT in a hanger.


Again....I still don't understand the heart burn about the new radios.  Except for the cost.....the system is better in every conceivable way.

[lordmonar]

The reason that this was done was because some fool arbitrarily decided that all emergency location was to be done on 406, rather than spending the $100 per satellite ($5 for the circuit, $95 to boost the extra two ounces to orbit) to put decoders on 121.5 and 243.0.

Yep....that's right....just because.  Forget that the fishing industry is the primary users of the SAR system......they are just some arbitrary fools.

Bottom line.....you are way to late to this argument to be bringing up "arbitary" changes as the reason why you don't like it.

Move on.

[JeffDG]

Slightly Off Topic, but how many of you pilots out there monitor 121.5 when you fly?

If you read NOTAMS, and have the capability, you are:

ALL AIRCRAFT OPERATING THE IN UNITED STATES NATIONAL AIRSPACE, IF CAPABLE, SHALL MAINTAIN A LISTENING WATCH ON VHF GUARD 121.5 OR UHF 243.0.

[CJB]

My opinion is that emergency beacons in aviation are generations behind compared to the maritime radio systems.  Why can't the aviation community upgrade to something comparable to the GMDSS, or share the same system?

Older 406 beacons chirp and can be located by their Doppler effect on SARSAT.  Unfortunately, this takes a while.  Newer 406 beacons contain GPS receivers and transmit a packet of data that identifies the ship (if programmed of course) as well as GPS coordinates.  This is why the last known position of EPIRBs is immediately sent to the Coast Guard.

[Spaceman3750]

My opinion is that emergency beacons in aviation are generations behind compared to the maritime radio systems.  Why can't the aviation community upgrade to something comparable to the GMDSS, or share the same system?

Older 406 beacons chirp and can be located by their Doppler effect on SARSAT.  Unfortunately, this takes a while.  Newer 406 beacons contain GPS receivers and transmit a packet of data that identifies the ship (if programmed of course) as well as GPS coordinates.  This is why the last known position of EPIRBs is immediately sent to the Coast Guard.

Exact same thing that's already in 406 ELTs and PLBs.

[PHall]

Slightly Off Topic, but how many of you pilots out there monitor 121.5 when you fly?

If you read NOTAMS, and have the capability, you are:

ALL AIRCRAFT OPERATING THE IN UNITED STATES NATIONAL AIRSPACE, IF CAPABLE, SHALL MAINTAIN A LISTENING WATCH ON VHF GUARD 121.5 OR UHF 243.0.

Oh, I knew about that. But how many of you know about it and actually do it?

Military aircraft have a little easier time of it because most of the UHF transceivers they use have an extra receiver built into the radio that does nothing but monitor the 243.0MHz (Guard) frequency.

Too bad they don't have something like that in civilian VHF radios...

[lordmonar]

Yes...but even on the military aircraft.....Ch+GRD is not always selected.  I know on the platform I maintain....they almost never select it except when actually doing CSAR or CSAR Training.

[PHall]

In SAC, MAC and AMC it was/is required that one radio will have the GUARD Receiver turned on at all times.
Of course we had 2 UHF, 2 VHF and 2 HF radios. :angel:

[Buzz]

One reason for the freq change was so that ALL emergency beacons (marine, ground and aviation) were on the same frequency.

And this is a good idea . . .why . . ?

But your argument is kind of lame.

Even if they stuck with 121.5 as the only freq....then you would still have to buy new equipment.  Including DFers to process the digital encoded information.

No, _I_ would not have to buy new equipment.  I don't need the information carried in the digital burst, all _I_ need is to be able to hear the beacon and get a fix.  I wouldn't have to spend a penny more to do that, if not for them putting aircraft ELTs on the same frequency as every kid with a backpack beacon.

End state.......exactly what we got now.  SAR agencies still needing to buy new equipment and pilots still having to buy new equipment.

Sorry, I refuse to accept your straw man as the baseline.

Now here is the kicker.....

Unless you are an Airliner......no one is making you buy any new equipment.  AOPA successfully fought that.   

The 406's 121.5 signal is still audible for miles and miles
[/quote]

The new specification is for a 121.5 "supplemental signal" of 0.025 watts -- one fourth of the current 0.1 watt average output of ELTs.  That gives a maximum unobstructed and reliable useful range of about 5 - 7 miles at 121.5MHz, A3E modulation, compared to 30 - 50 miles at 0.1W.  Doubling that for best-case scenario give you 10 - 15 miles on the new unit, 60 - 100 miles on the current one

you just have to be closer.....which the 406 signals does for you.......15KM closer and 3-4+ hours faster!

The "406" part is the only complaint that I have.  If they had added this system to 121.5 ELTs, I would welcome it with open arms.  The only reason they chose to make the change was so that all beacons would be on the one frequency, like when all the kids in town got their Christmas CB walkie-talkies on Channel 11.  True, most SAR agencies would be buying 406 equipment anyway, to find EPIRBS, but the vast majority of locator equipment used in SAR for aircraft is bought and paid for by individuals, not by agencies.  Tests have repeatedly shown that the 406 beacon digital "fix" tolerance is significantly greater than the range of the 121.5 "supplemental" signal.  Some manufacturers of the new ELTs have opted to pair full-power 121.5 transmitters with the 406 transmitters because of this deficiency, but having two transmitters boosts battery drain (even though the 406 transmitter sends short bursts, they are also 5 watts, so drain is about the same as the 100 milliwatt constant squeal).

Sure, batteries are better now than they used to be, but if they had put the data burst on 121.5 there would be only one transmitter, thus longer operating time than powering two complete transmitters.

[Buzz]

Bottom line.....you are way to late to this argument to be bringing up "arbitary" changes as the reason why you don't like it.

Move on.

No, the bottom line is that we have lost a capability that is used to save lives, and it has been removed arbitrarily and unnecessarily, when the new stuff could have easily been ADDED.

But what the heck, I've only been doing SAR and communications since the early 1970s, both in CAP and professionally, so it's not like I actually know anything about it, compared to an expert such as yourself.

[Extremepredjudice]

if/when you do get the call you will not be out looking for some carrier only signal that turns out to be some defective TV tuner or a USB hard drive......because of the digital encoding.  So less false alarms, less wild goose chases for an ELT in a hanger..

how does a TV tuner or a USB hard drive send a radio signal? Just wonderin'

[RiverAux]

True, most SAR agencies would be buying 406 equipment anyway, to find EPIRBS, but the vast majority of locator equipment used in SAR for aircraft is bought and paid for by individuals, not by agencies. 

What?  I'd like to see some evidence to back that up.  While I'm sure there are a few personal DF units out there in CAP, I've never seen one in two wings in 15 years.  And if you're not talking about CAP, I'd like to know what group of individuals is doing missing airplane searches with personal DF equipment and that collectively have bought more DF equipment than CAP and a host of state and federal agencies combined. 

[Duke Dillio]

True, most SAR agencies would be buying 406 equipment anyway, to find EPIRBS, but the vast majority of locator equipment used in SAR for aircraft is bought and paid for by individuals, not by agencies. 

What?  I'd like to see some evidence to back that up.  While I'm sure there are a few personal DF units out there in CAP, I've never seen one in two wings in 15 years.  And if you're not talking about CAP, I'd like to know what group of individuals is doing missing airplane searches with personal DF equipment and that collectively have bought more DF equipment than CAP and a host of state and federal agencies combined. 

I have my own DF and I know two others in this wing who have their own as well.  I can give you the name of a group that was doing missing airplane/ELT searches with personal equipment but that haven't collectively bought more than CAP and the other agencies.  In fact, one member of my wing in particular has run into these yahoos more than three or four times.

http://www.pacifier.com/~nwelt/index.html

Don't know if they are still around but it is my understanding that they were a group of disgruntled CAP members who went out on their own.  That is my understanding anyways...

[lordmonar]

One reason for the freq change was so that ALL emergency beacons (marine, ground and aviation) were on the same frequency.

And this is a good idea . . .why . . ?

So the SAR agencies....only have to monitor one freq and only have to buy on set of equipment for all three type of ELT ememgencies. 

But your argument is kind of lame.

Even if they stuck with 121.5 as the only freq....then you would still have to buy new equipment.  Including DFers to process the digital encoded information.

No, _I_ would not have to buy new equipment.  I don't need the information carried in the digital burst, all _I_ need is to be able to hear the beacon and get a fix.  I wouldn't have to spend a penny more to do that, if not for them putting aircraft ELTs on the same frequency as every kid with a backpack beacon.

And you still have that function...nothing has changed.  THEY changed the ELT equipment and YOU still have the ability to idlely monityory 121.5 and report any signal hits.  You can still DF with your old stlye DF equipment, and you can still DF using body blocking methods with your on board NAVCOM radios.   Once again......other then signal strenght....nothing has changed for YOUR point of view.

End state.......exactly what we got now.  SAR agencies still needing to buy new equipment and pilots still having to buy new equipment.

Sorry, I refuse to accept your straw man as the baseline.

Not a staw man.....fact.  You are lamenting that YOU (as a Layperson Pilot) had to change equipment....but the bottom line is that the professional SAR agecies (which I include CAP into) are the only one's who count in this case....and of course the victums.....The increased reliabilty, unique signals, the digital encoding all equate to FASTER and more ACCURATE inital SAR information.  Something on the order of 3-6 hours faster and withing 5KM of the target instead of 20KM.  THAT IS SAVING LIVES!  Add the benifit of not having to chase a bunch of false alarms around.....

Now here is the kicker.....

Unless you are an Airliner......no one is making you buy any new equipment.  AOPA successfully fought that.   

The 406's 121.5 signal is still audible for miles and miles

The new specification is for a 121.5 "supplemental signal" of 0.025 watts -- one fourth of the current 0.1 watt average output of ELTs.  That gives a maximum unobstructed and reliable useful range of about 5 - 7 miles at 121.5MHz, A3E modulation, compared to 30 - 50 miles at 0.1W.  Doubling that for best-case scenario give you 10 - 15 miles on the new unit, 60 - 100 miles on the current one

Yep.....and?  On the old system you would be given an intial coordinate after 3-6 hours of the ELT activation with a search radius of 20Km.   Now you get an intial coordinate within 10 minutes with a search radius of 5Km.  The 121.5 signal is only included for the "terminal DF search" any ways.  It is not for intial notification, it is not for "I was crusing at FL300 and heard a signal"....it is for us to use the old DF equipment to find the ELT.

you just have to be closer.....which the 406 signals does for you.......15KM closer and 3-4+ hours faster!

The "406" part is the only complaint that I have.  If they had added this system to 121.5 ELTs, I would welcome it with open arms.  The only reason they chose to make the change was so that all beacons would be on the one frequency, like when all the kids in town got their Christmas CB walkie-talkies on Channel 11.  True, most SAR agencies would be buying 406 equipment anyway, to find EPIRBS, but the vast majority of locator equipment used in SAR for aircraft is bought and paid for by individuals, not by agencies.  Tests have repeatedly shown that the 406 beacon digital "fix" tolerance is significantly greater than the range of the 121.5 "supplemental" signal.  Some manufacturers of the new ELTs have opted to pair full-power 121.5 transmitters with the 406 transmitters because of this deficiency, but having two transmitters boosts battery drain (even though the 406 transmitter sends short bursts, they are also 5 watts, so drain is about the same as the 100 milliwatt constant squeal).

Sure, batteries are better now than they used to be, but if they had put the data burst on 121.5 there would be only one transmitter, thus longer operating time than powering two complete transmitters.

So your REAL problem is that we have share......or more appropriate we have change to share someone elses' frequency.