In article ,
Peter Dohm wrote:

2) One of the major arguments for the adoption of the 406Mhz system was
the ever expanding use of the 121.5Mhz beacons by hikers, boaters, and
probably others as well. IIRC, the new beacons were supposed to be
available for the various uses so that searchers would have greater reason
to presume which type of incident might be involved. (I have not ket up,
and don't know whether the change has helped; but there do seem to be some
similarities to the use of other emergency response systems.)

406Mhz ELT/EPIRB/PRB emit a distinct identifier and are supposed
to be registered, so false positives can often be taken care of
with a phone call and not a SAR team going out at 2am looking for
it.

4) In the event that most false or inadvertant activations actually occur
on airports, which would certainly make sense, then there should be a fairly
simple and cost effective method to observe, locate and deactivate the
beacons in question.

Most false activations are on airports (or marinas, EPIRBs are on
121.5/406 as well). Tracking down which specific plane/boat is
still very time consuming with 121.5 beacons. With 406 beacons,
it is much easier, if they are registered. Especially at airports,
the metal hangars make finding the activated 121.5 beacon very
challenging since the signal reflects all over the place.

Another unfun one to track is when someone sends a ELT/EBIRP in for
servicing, but doesn't remove the batteries. UPS trucks have
plastic tops, so the signal hits the satellite just fine, but
tracking the moving target from the ground is nearly impossible.

5) Crashes that occur away from the airports, where a search operation is
needed, probably involve a very small percentage of pilots and passengers
over their lifetimes. I really don't know how small that percentage is; but
if the percentage is as small as I suspect, then there is some question
about whether any system makes sense--with the exception of post crash
beacons in aircraft carrying passengers commercially and possibly combat
aircraft. (If the lifetime probability, for the participants in the
activity, is only one or two percent, then it is long past time to reopen
the debate about general aviation fleetwide use in terms of its value versus
cost in money, time, effort, freedom and privacy.)

ELTs were originally mandated by Congress after Congressman Hale
Boggs's plane went missing in 1972 (and still hasn't been found).
There never was a serious discussion of the cost/benefits of ELTs.
http://en.wikipedia.org/wiki/Hale_Bo...nce_and_search

I haven't seen any stats, but I feel the number of survivable
crashes where an ELT assisted in the rescue is very small. On the
water, a large number of rescues have been the result of EPIRB
activations. I've heard ELTs referred to as ballast, since the
most useful thing they do is move the CG aft.

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