On Friday, April 27, 2012 11:40:27 AM UTC-7, John Clear wrote:
In article 30263873.0.1335547569413.JavaMail.geo-discussion-forums@pbboj7,
kirk.stant wrote:

Ditto with the fancy 406 + GPS PLBs - they are great if you need rescue
- but they are not ELTs; they (just like the SPOT basic service) need to
be activated by the survivor to be of any use. But if you go down, it
could be a lifesaver!

A PLB is just a manually operated ELT/EPIRB.

I carry this one:

http://www.aeromedix.com/ACR-Resqlin...eacon-GPS.html

It is about the size of a cell phone, and I use a cell phone case
to keep it on my belt.

When I was in CAP, we'd call ELTs ballast. When you need it, there
is high failure rate. The 15% activation rate in crashes mentioned
up thread is quite possibly optimistic. A stat I saw was that 99%
of ELT/EPIRB activations were false alarms. Chasing the UPS truck
at 2am is one of the reasons I left CAP.

John
--
John Clear - http://www.clear-prop.org/


Two different but worrisome stats. 15% or so is the correct activation rate when you need it, i.e. the device activates after a crash (but even if corect for GA I suspect its lower in sailplanes because of the poor/incorrect installations I've seen and the low energy of some glider crashes). The 99% or so is the percent or false activations. Both numbers are very rough but probalby give a reasonable feel of the issues here. The high-false activation rate of ELTs is why a old style 121.5 MHz only ELT signal won't necessarily result in a search -- unless people are reporting you missing and local SAR folks are searching. I expect many of us have seen the CAP folks turn up at a gliderport looking for an old ELT going off in a trailer or some other similar thing, a complete and utter waste of their time.

I encourage folks to use a SPOT and an 406 MHz ELT or PLB. If you already have a 121.5 Mhz ELT and don't want to upgrade, at least know its limitations (including no SARSAT detection and no guarantee of automatic search). With ELT mounting and antenna issues, poor crash activation rates and desire to be able to manually activate with a separate antenna is the glider is upside down/antenna damaged etc. I've decided I'd rather have a SPOT mounted on the glider and a PLB on my parachute (instead of an ELT in the glider). Of course if you can find a way to do a SPOT and both and ELT and PLB...

Darryl