In Australia, legislation to mandate fixed ELT in all GA aircraft was
defeated in the Parliament, after a lobbying campaign by AOPA Australia.
We do have legislation for the mandatory carriage of handheld
ELT/EPIRB ( your PLB) on all flights over 50 miles from base.
The statistics are stark, in actual crash scenarios, the failure rate
of fixed ELT is around 95%.
The most common cause of failure is the disruption of the antenna or
the aerial cable from the box to the antenna, for all the reasons you
can think of.
Another common reason is that the aircraft is in the water , 100% of
ELT's do not work under water. Post accident fire, prior internal
failure etc, are common additional causes.
In contrast, in survivable accidents, 100% of hand held ELT have
worked. In non-survivable accidents, all you are talking about is
saving search costs. Given what little information is available in
the US ( I did a lot of work jointly with the Civil Air Patrol on the
subject) the 95% + failure rate holds good in the US ---- As you
might expect, given the causes of failure are inherent in the
design/installation of fixed ELT.
Remember that the US legislation to mandate ELT bypassed all the
usual consultation, cost benefit analysis etc, it was a knee jerk
political reaction to the loss of an aircraft in Alaska, I don't
recall if it was a Congressman or Senator that was lost. There is
absolutely NO evidence to show that the outcome of that accident
would have been any different had the aircraft been fitted with an
ELT, statistically there was a better than 95% failure probability.
Given actual accident, the failure probability was closer to 100%.
In view of phasing out the COSPAR/SARSAT on 121.5/243, in accord with
the latest specifications for new generation ELT, commodity priced
400 mcs GPS/ELT are now available.
Interestingly, because of the low cost of an ELT, their use is
widespread, even Forest Service type organisations ( the name varies
state by state) rent ELT to hikers who do not have their own, most 4
Wheel Drivers carry one now, if they are in a remote area.
In short, fixed ELT are a total waste on money.
Even in three airline accidents ( all Airbus) that we could track
down, where the tail mounted ELT survived in-tact in a largely intact
tail section, all three ELT failed to transmit a useable signal.
At 21:28 10/02/2006, you wrote:
>--> Avionics-List message posted by: <bakerocb@cox....>
>Responding to an AeroElectric-List message previously posted by: "bob noffs"
>Hello Bob, Dare I post some heresy? Will the gummint sic its watch dogs on
>me? Will the electromagnetic radiation purists on the list rise up in total
>fury to slap me down? Well, I'll take a chance.
>Suppose that the gummint, in its infinite wisdom, mandated that every
>aircraft carry 3 pounds of butter and a container of maple syrup just in
>case the survival situation after crashing resulted in a supply of pancakes
>as the available food supply. Would you insist on carrying genuine maple
>syrup or would an imitation be good enough for you?
>Maybe an ELT is a little more useful than butter and maple syrup in a crash
>situation, but I sure as hell wouldn't place my entire faith in being found
>and rescued in one of the garden variety ELT's that we are mandated to
>carry. My point is that obsessing over antenna ground plane details is
>Nobody knows exactly what attitude their aircraft will be in when it
>finishes crashing. The ELT antenna could end up pointing directly down at,
>and a few inches from, the surface of the earth. How much difference would a
>perfect ground plane, if one could construct one, make in that situation?
>Here is my thinking:
>1) To be legal, buy one of the garden variety ELT's that we are mandated to
>carry. Install it securely in the proper location in the proper attitude
>with regard to its deceleration sensor. Fasten on the wire antenna that came
>with the ELT and don't obsess over ground planes or what the antenna's
>attitude will be when you finish crashing. Go fly.
>2) If you want to take some truly effective steps for rescue after crashing
>you can, and probably should to the degree that you are concerned and
>considering routes of flight, do some or all of the following.
>2A) Always carry a hand held VHF comm radio with a battery supply that you
>KNOW to be capable of extended operation.
>2B) Always carry a cell phone with a battery supply that you KNOW to be
>capable of extended operation.
>2C) Purchase and carry a PLB http://www.equipped.com/faq_plb/default.asp >
>2D) Carry a tough plastic container of water -- size your choice. My
>experience with even short time rescued people is that they experienced an
>almost mentally debilitating thirst shortly after crashing.
>2E) Carry a knife of enough size and sturdiness to punch through / crack
>your plastic windows and canopy.
>I am sure that other posters will add their favorite / essential crash
>survival items, but obsessing over these items falls into the same category
>of time wasting like obsessing over ground planes. Take what you deem to be
>reasonable precautions to be rescued after a survivable crash and then
>proceed to fly worry and guilt free (and legal).
>PS: If you have the bank account to afford one of the new 406 Mhz ELT's, go
><< hi all, I have several antennas to install. My elt requires a ground
>plane. Tim at b and
>c was very helpful with my questions but i question leads to 5 more. Is
>any way around a ground plane for the elt? If not, any suggestions on how to
>make it in my wood/cloth fuselage? At first i thought numerous strips of
>copper way the way to go but that looks like just more fasteners. Can a very
>thin sheet be laid down in the fuse. bottom? It wouldnt exactly be flat with
>all the woodworking to go around.....skip.....Thanks in advance, bob noffs>>
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