Question re PLB frequency

[Andy_P]

I am studying for my first exams, and I am interested in PLB frequencies and regulations. I am in AUS, so under CASA regulation.

I am sailor, and if I sail more than 2nm offshore I have to have an EPIRB. The new rules here specify that I have now have to have one of the new 406MHZ beacons. Do aircraft use the new beacons or are they still on the 121.5/203Mhz beacons? All my practice exams refer to the old beacons.

I know that the new 406MHz beacons still emit a 121.5 MHz homing signal. Just want to get this stuff right on my exam. Google has provided me with much confusion.

[dubbleyew eight]

look up this link to the GME gps capable beacon we use in australian light aircraft

EPIRBS | GME

[Whopity]

Google has provided me with much confusion.

Much the same in the UK. The SARSAT that operated on 121.5 produced an excessive number of false alarms due to the large number of devices around the World capable of transmitting on 121.5 MHz. 406MHz had long been the ELT frequency and such devices were removed from aircraft in the UK untill EASA appeared then they started to re-appear. PLBs now operate on 406 MHz for sattelite pick up and as you say also provide a weak homing signal on 121.5 MHz. Having flown aircraft with homers for many years, they were always on 243MHz the military frequency, not 121.5 MHz the civil frequency

[Andy_P]

Should probably have said ELT in the topic. Too tired last night, trying to process to much info..

So I tracked down the regulation, and it is indeed the new type (406MHz) beacon that is required in Aus.

http://www.casa.gov.au/wcmswr/_asset...elt_annexa.pdf

Also have no idea how I missed this, but its on CASA's website spelled out clear as day: Civil Aviation Safety Authority - Emergency Locator Transmitter (ELT) changes

[SawMan]

The Skinny

406 is the only officially monitored civilian frequency nowadays, though some EPIRB's in non-revenue GA aircraft in the US still have only 121.5 units, as do some private coastal watercraft. A/C worldwide are still required to monitor 121.5 MHz 'guard', VHF equipped commercial watercraft are still required to monitor 'guard' on channel 16. Any other monitoring is voluntary and local only.
All of the new 406 MHz units must be registered with the appropriate authotrities as all TX a serial number to identify each unit.

Some of the confusion relates to the different types of EPIRBS being offered now. Basic ones TX only a coded signal on 406 at low power. Burst transmission is used and may cease after 48 hours due to battery life expiring. Better ones have higher power but this also requires better batteries, better than that has built-in GPS, and the best for AC have all that plus a low power 121.5 TX for old-fashioned close-in DF work.

With new basic units it may take as much as 2 hours to get a position fix good enough to initiate more than a general response- I don't think those are approved for any types of AC. High-powered ones will be more readily captured by multiple satellite receivers , thus rarely have more than a few minutes before a 'position fix' is worked out. GPS-equipped units have a response time measured in seconds. The 'local' 121.5 beacon may be useful for pinpoint SAR locating in mountainous or forested terrain but is all low-power so as to not interfere with 'guard' monitoring.

The new 406 units are less likely to be unintentionally activated by a hard landing but always check before leaving the AC when you aren't sure. In some countries you will get the bill for the SAR efforts if there was no emergency! If it were me, I'd go with a GPS equipped unit for most areas, and if I was often over mountainous or forested areas I'd opt for the 121.5 option too (which is supposed to be limited to aircraft EPIRBs only). Wikipedia has good info on this which I have verified in the US through the FCC website.

The old HF 'guard' of 2183 kHz is no longer supported and the 121.5 MHz VHF 'guard' is only monitored by A/C. Everything except Military is now on 406 MHz only so that's what you need and indeed is required by law in many nations for some or all A/C and for all Maratime use beyond coastal waters. Something is better than nothing if you've legally got a choice, but I tend to value my hide highly and would choose accordingly!

[Andy_P]

Just to add SawMan, PLB's in Aus dont need to be registered. Marine EPIRB's do, as do ELT's. Marine EPIRBS HAVE to have the registration sticker attached here in Queensland, without it you get a pretty steep fine if you get caught.

Of course when you purchase a PLB here (I have one for trailbike riding) they actively encourage you to register it (mine is)

I think I also read in the AIP that coverage is worldwide for the 406mhz beacons, but may take upto 2 hours for a satellite to pass over in some places. I will have to check up on that one. May only be for the GPS enabled ones.

[rjtjrt]

Andy
Here in Australia it is 406 for the PLB's. As you say they also transmit on 121.5 to assist rescue aircraft with the last part of homing during the rescue phase.
The up to 2 hours before a fix on the 406 signal is for the non GPS version - they need a low earth orbit satellite to get a doppler result to establish position.

With the GPS version of the 406PLB (or EPIRB in marine case) the GPS position is known virtually instantaneously as the Geostationary satellite picks up the initial 406 signal and in that signal the GPS position is also available.
John

[Jumbo Driver]

Originally Posted by SawMan

The old HF 'guard' of 2183 kHz is no longer supported and the 121.5 MHz VHF 'guard' is only monitored by A/C.

I expect it was a typo, SawMan, but I think you mean 2182KHz, don't you ?

JD