PLB/EPIRB on airplanes?

[cdiver2]

Yeah, I called the NOAA and McMurdo over that and both said that there was no problem using it overseas as long as it was registered in the USA. I'm thinking, at this point, that if I ever get to the point where I feel that I need to use this, then I'll be happy to pay the fine if they'll just come and try to collect .







My daughter's BC (she's the one that got the PLB, for obvious reasons) has an extra tank strap and we mounted the PLB to that.



Good to know, thanks! I'll check into that!

BTW, we're back from the Palau trip and had no need for the PLB . It was cool how the other divers were curious about it and liked the idea of having one. Our dive guide told us that it would have been nice for some divers to have had one a few years ago -- 7 divers got lost at sea from Pelileu (sp?) but they only found 3 of the bodies. Yikes!

I'm curious -- why wouldn't they be timely?

There are no US coastguard stations in Palau. The nearest station would be in Guam.
I think it go's something like this.
In the event someone activated a PLB in Palau the coastguard would first check the contact numbers you gave when you registered it, then they may put out a HF radio call to all shipping in the area and then call a Palau authority giving your location.

 

[vladimir]

I think it go's something like this.
In the event someone activated a PLB in Palau the coastguard would first check the contact numbers you gave when you registered it, then they may put out a HF radio call to all shipping in the area and then call a Palau authority giving your location.

I was thinking it would go something like this: beacon gets activated, contact number gets called, my sister tells them that I'm on the Palau Aggressor, they call the Aggressor with my GPS coordinates, and the Aggressor comes and gets me, perhaps homing in on my 121.5 Mhz homing signal.

 

[ba_hiker]

The goal of the COSPAS/SARSAT system is to respond with in one day. It is designed with that in mind. They are part of a bigger system called GMDSS, defined by the SOLAS treaties. The are targeted for people in life boats or rafts, not floating divers.

Assuming that it has a good GPS location it goes like this:

The radio transmits a signal to a satellite (a GEOS II weather sat, used for COMPAS/STARSAT) that retransmits the signal to one of seven "local user terminal" stations. The satellites are overhead about once every 90 minutes. After two reports, by different satellites, the operator at the local user terminal transmits a report to a "regional rescue coordination center" this generally takes 1 1/2 hours. Two reports are required to minimize 'false positives’; there are many false positives every day.

The regional coordination center (originally there were 25, now probably a few more) then verifies the number and related information and contacts a local 'rescue coordination center', which decides what to do. Outside of the USA the US Coast guard is not involved, except that they operate a few of the local user terminals. Close inshore rescue is a national responsibility.

The locals decide what action to take, if any. They will take some action for reports from large ships, but may defer action on other reports. Often, for EPIRBs registered to small users, they notify local police or boat owners who undertake a search. They are unlikely to call you sister or anyone else. It is unlikely that any dive boat or other small boat can home on the receiver.

Homing on the 121.5 radio beacon is troublesome for a ship. The transmitter is only about .25 watts on the fast find (.5 watts on larger units) and most ships do not have equipment to receive it or do direction finding on this frequency. The range for an in the water target may be less than 1/2 mile. The 406 mz is even more troublesome for surface detectors; it is 2 to 5 watts and has unusual propagation characteristics. Both are useful for search aircraft homing; they can detect it from 5000 feet for perhaps 5 miles (minimum 2 km).

If the GPS signal is bad, they will use Doppler location to locate the transmitter, and this will take at least two passes by different satellites in different orbits and take 6 to 8 hours, often additional passes are required. Then the user terminal operator will contact the regional coordination center. They will have you location within a 25 mi circle; notification time to the regional center is on the order of 24 hours.

This is all governed by international treaties. Flares and other short range signaling devices is suggested in conjunction with any EPIRBs.

 

[ba_hiker]

Did a little research on search and rescue in and arround Palau. Independent of the EPIRB info I posted earlier.

It appears that the USA has a defence obligation with Palau based on a 1970's treaty, and will participate in search and rescue.

Air force (and Coast guard if any is arround) will participate in search and rescue. Airforce pararescue units, based in the Philipines will probably dispach with in hours of contact by the regional rescue coordination center, which seems to be operated by the coasties in the Philipines. The pararescue units use C-130s equiped to home on the 121.5 and 406 radio componets of the EPIRB.

 

[stiebs]

Some good information there ba_hiker, but just some clarification:

121.5Mhz beacons don't transmit a digital signal, and a lot of alerts are generated by a host of other devices (microwaves, ATMs, etc) which is why they wait for a second satellite pass before raising an alarm.

406Mhz beacons include a digital signature (which is why you are required to register them) so the first alert which can be immediate if you're in range of a geostationary, otherwise usually within 45 minutes, will trigger action in the form of contacting someone as per your contact details.

 

[Diver Dennis]

The bodies of the Japanese divers that were found in Palau were spotted by a C-130 out of Guam on the third day they were missing.

 

[ba_hiker]

Some good information there ba_hiker, but just some clarification:

121.5Mhz beacons don't transmit a digital signal, and a lot of alerts are generated by a host of other devices (microwaves, ATMs, etc) which is why they wait for a second satellite pass before raising an alarm.

Quite correct.

Other causes of false alerts is that people fiddle with the units and accidently triger them for a minute, similar devices are usde in aircraft and may signal on a hard landing and many many other reasons. In the continential US about 95% of the signals detected are false positives.