SAR Satellite System Changes

[flipster]

I read (in a yachting mag!) that, from Feb 09, the COSPAS/SARSAT satellite system will no longer scan 121.5 and 243 but will only scan 406 mHz, rendering many current EPIRBs and PLBs useless.

Would any SAR-boys (or girls) care to comment on the validity of this statement and any possible implications for aviation that may have slipped us by? How, if at all, will this affect the use of 121.5/243 voice tx?

Also, anyone with Breitling watches that have a built-in EPIRB care to comment!?

flipster

[Spacer]

Flipster,

For the watches, nothing will change. The new 406mhz beacons will still have an embeded 121.5 beacon for "final stage" homing. The Emergency was only designed as a location aid, and so was never meant to alert people to the fact you may be missing/in trouble. In fact, it hasn't got the power to reach the sat at the moment, so by them switching freqs it won't have any impact on the watch. I believe that most 406 beacons will be GPS embeded, so a SAR unit would be scrambled to a lat/long provided on 406 and then use 121.5 at a close range to provide final homing.


Hope this helps, and I may be completely wrong!

[ionagh]

I may be completely wrong!

No, pretty much spot on.

Most EPIRBs and PLBs are specifically designed to have the VHF radiated power level at a level that is guaranteed never to reach the satellite. It is only there for a close-in beacon.

[Sven Sixtoo]

Further to the above posts, which are accurate, it is important to note that the only thing that is changing is satellite alerting / fixing. 121.5 MHz and 243.0 MHz will still be in use for SAR purposes, the UK UHF and VHF fixing service will still work, and SAR aircraft will still do final homing on 121.5 or 243.0. The 406 MHz signal is unsuitable for homing (though perfectly OK with the right kit for DF). It is only transmitted for 0.5 seconds every 50 seconds, which equates to something around 2 miles between indications. As a result, getting an accurate on-top on 406 is problematic at best. The GPS position from a 406 beacon has to go through, by my reckoning, nine links before it ends up as steering information in a SAR helo. Therefore it would be unwise to rely on it absolutely. For that reason among others, any internationally-certified beacon has to have a 121.5 transmitter as well as the 406 element. The satellites can then generate a fix off the 406 transmission, and that will get the SAR platform close enough to finish the job on 121.5

If you feel the need for a personal beacon, I would buy a purpose-built one for something around £150, and if you feel the need for a fancy watch, the Breitling timekeeping bit is available in various versions for about £2000 less than the Emergency watch. You gain a four-figure sum, which you might then spend on a properly certified 406 beacon, or some other survival gear or some serious survival training - or on beer, which won't extend your survival chances but might be more fun.

Sven

[flipster]

All,

Thanks for your kind information - I am enlightened.

BTW I can't afford a real Breitling - without or without EPIRB!

(The best I could manage was a $20 imitation bought on the strip outside Incirlik! It was still going 6 years later but eventually went phut!)

flip