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ELT Antenna Placement

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bakerocb

Joined: 15 Jan 2006
Posts: 727
Location: FAIRFAX VA

Posted: Thu May 18, 2006 3:23 am Post subject: ELT Antenna Placement

Responding to an AeroElectric-List message previously posted by: "Dan 

Beadle" <Dan.Beadle(at)hq.InclineSoftworks.com>



I am building RV8. I am trying to figure out all the antenna placements

before closing up the wings.



.....skip.......* ELT - should be on top - maybe just ahead of Vert 

Stab.....skip



5/18/2006



Hello Dan,  One of my friends commented that I had my ELT antenna installed 

with

improper orientation. I said "Fine, tell me just exactly what attitude my

fuselage will be in when I am finished crashing and I will reinstall my

antenna accordingly." He smiled and got the point.



What attitude will your fuselage be in when you finish crashing?



OC



PS: The garden variety 121.5 Mhz ELT is just congressionally mandated dead 

weight. Put the ELT in because you have to. Carry a personal locator beacon 

because you want to. http://www.sarsat.noaa.gov/emerbcns.html. A cell phone 

and a hand held VHF comm radio are also beneficial.

nuckollsr(at)cox.net
Guest

Posted: Thu May 25, 2006 4:46 am Post subject: ELT Antenna Placement

At 07:19 AM 5/18/2006 -0400, you wrote:



 	  Quote: 	
		  



Responding to an AeroElectric-List message previously posted by: "Dan

Beadle" <Dan.Beadle(at)hq.InclineSoftworks.com>



I am building RV8. I am trying to figure out all the antenna placements

before closing up the wings.



......skip.......* ELT - should be on top - maybe just ahead of Vert

Stab.....skip



5/18/2006



Hello Dan,  One of my friends commented that I had my ELT antenna installed

with

improper orientation. I said "Fine, tell me just exactly what attitude my

fuselage will be in when I am finished crashing and I will reinstall my

antenna accordingly." He smiled and got the point.



What attitude will your fuselage be in when you finish crashing?



OC


	


    The reasoning behind placement of ELT antennas just forward of

    the vertical fin has nothing to do with final orientation of

    wreckage . . . and lots to do with using the vertical fin

    structure to protect the antenna as much as possible.



    The 121.5/406 MHz antennas on a Beechjet are mounted under

    a fiberglas toe-cap at the base of the vertical fin. See:



http://www.aeroelectric.com/temp/400A_ELT.jpg



    This is about as protected a location as one can devise . . .



        Bob . . .

      ---------------------------------------------------------

      < What is so wonderful about scientific truth...is that >

      < the authority which determines whether there can be   >

      < debate or not does not reside in some fraternity of   >

      < scientists; nor is it divine. The authority rests     >

      < with experiment.                                      >

      <                            --Lawrence M. Krauss       >

      ---------------------------------------------------------

gmcjetpilot(at)yahoo.com
Guest

Posted: Fri May 26, 2006 9:22 am Post subject: ELT Antenna Placement

Reading TSO'ed instructions for different brands of ELT's 

they all tell you basically the same thing, to mount antenna: 

   

  -Vertical

  -Top of fuselage 

  -Externally mounted 

  -Near ELT transmitter 

  -ELT is far aft as possible w/ access

   

  (if you read between the lines there are good reasons 

for every point in the installation instructions. The ELT 

manufacture, not the aircraft manufactures, researched 

tons of data from accidents. For best survivability of 

antenna and ELT follow the instructions.)

  

Here is a typical oh-oops:

   

  http://img344.imageshack.us/img344/7985/eltant7cc.jpg

   

  I marked possible locations for ELT antenna. Of course who 

know what position or condition the plane will be after a crash, 

  but the ELT makers know after much study the most likely.

   

  I never read an ELT installation instruction where it stated the 

reason for the ELT antenna top location is protection by the 

Vert stab as Bob suggest, but from the picture it makes sense. 

   

  I also read accident reports where the ELT's are ripped off mounts 

in a crash. Some crashes are just not survivable for the ELT or 

the people, however talking to ELT mafct they might know better 

than anyone.

   

  FACTORY installations of ELT antennas and ELT's are not a 

model of best practice. Don't know about Beech Jets but 

in at least two ELT instructions there are warnings not to 

necessarily follow previous factory installations when replacing 

  an ELT. Some factory installations are terrible.

   

  Of course the old debate is do experimental aircraft need to 

follow the TSO'ed equipments TSO'ed installation instructions?

   

  Leave the answer to you.

   

  As was stated there is no TSO'ed approved CRASH, so who 

knows. However it's fair to say if you do want to be found the 

installation instruction that came with your ELT should be 

followed

  

If you really want to be found, the new 406 Mhz will do that better  

than the old 243. The search area ratio is: 

   

  450 sq miles (old 121.5/243 Mhz)

12.5 sq miles (new 121.5/406 Mhz)

1.5 mile radius (new w/gps 121.5/406 Mhz)

   

  How long do you think 450 sq nm can be searched with a 

121.5 direction finder when your antenna is smashed down 

into the ground or hidden UNDER your vertical & horz stab?

   

  Cheers George

   

  

 	  Quote: 	
		  >posted by: "Robert L. Nuckolls, III" <nuckollsr(at)cox.net>

>

>Responding to post by

  >>"Dan Beadle" <Dan.Beadle(at)hq.InclineSoftworks.com>
	


 	  Quote: 	
		  >

>I am building RV8. I am trying to figure out all the antenna 

>placements before closing up the wings.

>

>......skip.......* ELT - should be on top - maybe just ahead 

  >>of Vert Stab.....skip
	


 	  Quote: 	
		  >

>

>Hello Dan,  One of my friends commented that I had my 

>ELT antenna installed with improper orientation. I said "Fine, 

>tell me just exactly what attitude my fuselage will be in 

>when I am finished crashing and I will reinstall my antenna 

>accordingly." He smiled and got the point.

>

>What attitude will your fuselage be in when you finish 

  >>crashing?
	


 	  Quote: 	
		  >

>OC

       >The reasoning behind placement of ELT antennas just forward 
	


    >of the vertical fin has nothing to do with final orientation of

    >wreckage . . . and lots to do with using the vertical fin

    >structure to protect the antenna as much as possible.

    >The 121.5/406 MHz antennas on a Beechjet are mounted 

    >under a Fiberglas toe-cap at the base of the vertical fin. See:

 	  Quote: 	
		  

 http://www.aeroelectric.com/temp/400A_ELT.jpg



    >This is about as protected a location as one can devise . . .
	


        >Bob . . .

   



 __________________________________________________

craig(at)craigandjean.com
Guest

Posted: Fri May 26, 2006 10:02 am Post subject: ELT Antenna Placement

The instructions for my new Artex ME406 406 MHz ELT have additional

requirements:



"Locate the antenna at least 30 inches away from other antennas, wires,

vertical stabilizer, etc. to minimize distortion of the radiated field and

interference with other equipment. The antenna must be installed VERTICALLY

(within 15 of the vertical plane is acceptable). Artex has no performance

data for installations that deviate from the stated requirements."



(http://www.artex.net/documents/570-1600Rev-1.pdf)



This is almost impossible on my Zenith 601XL so I am doing the best I can.



-- Craig

rvbuilder(at)sausen.net
Guest

Posted: Fri May 26, 2006 10:57 am Post subject: ELT Antenna Placement

Of course if you would happen to need the ELT, make sure you crash in =

a way to meet all of those requirements.  

Michael Sausen

RV-10 #352 Working on Fuselage

Do Not Archive



--

nuckollsr(at)cox.net
Guest

Posted: Sat May 27, 2006 5:17 am Post subject: ELT Antenna Placement

At 12:00 PM 5/26/2006 -0600, you wrote:



 	  Quote: 	
		  

<craig(at)craigandjean.com>



The instructions for my new Artex ME406 406 MHz ELT have additional

requirements:



"Locate the antenna at least 30 inches away from other antennas, wires,

vertical stabilizer, etc. to minimize distortion of the radiated field and

interference with other equipment. The antenna must be installed VERTICALLY

(within 15 of the vertical plane is acceptable). Artex has no performance

data for installations that deviate from the stated requirements."



(http://www.artex.net/documents/570-1600Rev-1.pdf)



This is almost impossible on my Zenith 601XL so I am doing the best I can.


	


    . . , which is all anyone can. Virtually every manufacturer cites

   their fondest wishes in the installation manual that virtually

   never work out in real life.



   Generally, effects of 'deviations' require laboratory grade

   instruments to detect and quantify . . . and most have no

   major contribution to the outcome of any given crash/recovery

   scenario.



   Don't loose any sleep over it.



   Bob . . .

      ---------------------------------------------------------

      < What is so wonderful about scientific truth...is that >

      < the authority which determines whether there can be   >

      < debate or not does not reside in some fraternity of   >

      < scientists; nor is it divine. The authority rests     >

      < with experiment.                                      >

      <                            --Lawrence M. Krauss       >

      ---------------------------------------------------------

craig(at)craigandjean.com
Guest

Posted: Sat May 27, 2006 11:04 am Post subject: ELT Antenna Placement

 	  Quote: 	
		  >   Don't loose any sleep over it.

>

>   Bob . . .


	


The other listed requirement is "do not crash" 



-- Craig

gmcjetpilot(at)yahoo.com
Guest

Posted: Sun May 28, 2006 10:52 am Post subject: ELT Antenna Placement

Dear Bob:

   

  To imply or suggest that an ELT is not important or complying 

with installation instructions is of little consequence is not the 

precise scientific well thought out response I've come to expect 

out of you. The manufactures of ELT's provide instructions based 

on  facts and service (crash) history. 

   

  I partially agree with you, not to lose sleep and often the ELT

installation instructions can't be fully met on some small planes. 

  

However to say:

   

  *deviations..MOST have no major contribution to the outcome  

of ANY crash/recovery scenario*  is shooting from the hip. 

   

  MOST? ANY? Have proof? Data? Define, what is a deviation?

   

  No offense, flying over Kansas or what ever flat state you're in, 

is not like flying over wilderness in the Western half of the US, 

Canada and Alaska, I am glad to have an ELT installed per 

manufactures recommendations.

   

  ELT manufactures might know something, you think Bob?

  

My suggestion is try to comply as much as possible. I know if 

you call the manufacture they can provide guidance solution 

 (compromise). It will be more than it does not matter.

  

Please don't make this about you being right and me wrong.   

This is about learning. A cavalier attitude is not appropriate to 

the topic. Bob, you pride yourself in your facts and repeatable 

experiments. I say the 1000's of crashes that the manufacture 

and FAA have studied in developing the guidelines have merit, 

period. If you have specifics than please say, but the general 

dismissal of ELT manufactures recommendation as found 

wishes is condescending.

   

  Bob you often have FONDEST WISHES for your ideas and 

concepts, you claim are based on irrefutable logic and 

experiments. I think you should give other professionals in 

the aerospace industry the same professional courtesy and 

respect for their expertise.

   

  Cheers George ATP/CFII-MEI, B73/75/767



  

 

  

 

   

   

  >posted by: "Robert L. Nuckolls, III" <nuckollsr(at)cox.net>

 	  Quote: 	
		  . . , which is all anyone can. Virtually every manufacturer cites

their fondest wishes in the installation manual that virtually

never work out in real life.



  >Generally, effects of 'deviations' require laboratory grade
	


 	  Quote: 	
		  instruments to detect and quantify . . . and most have no

major contribution to the outcome of any given crash/recovery

scenario.

Bob . . .


	




 __________________________________________________

brian

Joined: 02 Jan 2006
Posts: 643
Location: Sacramento, California, USA

Posted: Sun May 28, 2006 12:36 pm Post subject: ELT Antenna Placement

On May 28, 2006, at 11:43 AM, <gmcjetpilot(at)yahoo.com>  

<gmcjetpilot(at)yahoo.com> wrote:



 	  Quote: 	
		   



 Dear Bob:



   To imply or suggest that an ELT is not important or complying

 with installation instructions is of little consequence is not the

 precise scientific well thought out response I've come to expect

 out of you. The manufactures of ELT's provide instructions based

 on  facts and service (crash) history.



   I partially agree with you, not to lose sleep and often the ELT

 installation instructions can't be fully met on some small planes.



 However to say:



   *deviations..MOST have no major contribution to the outcome

 of ANY crash/recovery scenario*  is shooting from the hip.


	


George,



The ELT is a waste of time and money. They have 97% false positives  

and who knows how many false negatives. Precious few have been saved  

by an ELT but a lot of people have gone on wild goose chases because  

of 'em.



So, based on those facts, the placement and installation of your ELT  

is going to have very little effect on its actual usefulness since it  

is basically useless from the get-go. Since we are bound by law to  

install these useless things in our airplanes at least we have the  

option of putting them where they will be the least intrusive.



As others have stated, telling someone where you are going, what  

route you are taking, and when you are going to get there is much  

more effective in case of an accident than is an ELT.



And last but not least, dumping on Bob for stating the obvious is  

pretty useless too.



Brian Lloyd                         361 Catterline Way

brian-yak AT lloyd DOT com          Folsom, CA 95630

+1.916.367.2131 (voice)             +1.270.912.0788 (fax)



I fly because it releases my mind from the tyranny of petty things . . .

 Antoine de Saint-Exupry

_________________
Brian Lloyd
brian-yak at lloyd dot com
+1.916.367.2131 (voice) +1.270.912.0788 (fax)

I fly because it releases my mind from the tyranny of petty things . . .
- Antoine de Saint-Exupery

Gilles.Thesee(at)ac-greno
Guest

Posted: Sun May 28, 2006 1:01 pm Post subject: ELT Antenna Placement

 	  Quote: 	
		   The ELT is a waste of time and money. They have 97% false positives  

 and who knows how many false negatives. Precious few have been saved  

 by an ELT but a lot of people have gone on wild goose chases because  

 of 'em.



   

I have personnaly witnessed more than a dozen such wild goose chases for 
	


ELT gone wild while sitting on the ramp.



About a decade ago, two friends took a plane in our flying club, for a 

40 minute flight to Annecy in the French Alps. They never returned.

We spent more than a week searching the whole area, by air and on the 

ground.



Finally a rambler found the wreck just two miles South of the airfield, 

6000 ft high in the mountains. When the rescue helicopter landed near 

what remained of the airplane, they heard the ELT transmitting : the 

battery was still in good shape after 8 days, but the certified factory 

installed antenna radiated only only a few yards away.

At least one of them had survived the crash, and died of exposure...



Had the antenna worked as expected, they would have been found within 

hours after being overdue.



As homebuilts are not subject to ELT obligations in may area, I have the 

impression that a cellphone provides much more accurate positioning 

information, and for free.



Regards,

Gilles Thesee

Grenoble, France

http://contrails.free.fr

rvbuilder(at)sausen.net
Guest

Posted: Sun May 28, 2006 1:12 pm Post subject: ELT Antenna Placement

May be next to useless but only an idiot would take dead over 3% chance.



My short $0.02 on this mostly useless thread tangant.



Michael Sausen



And do not archive this whole thread.  (wish that worked)



--

nuckollsr(at)cox.net
Guest

Posted: Mon May 29, 2006 6:24 am Post subject: ELT Antenna Placement

At 11:43 AM 5/28/2006 -0700, you wrote:



 	  Quote: 	
		  



Dear Bob:



   To imply or suggest that an ELT is not important or complying

with installation instructions is of little consequence is not the

precise scientific well thought out response I've come to expect

out of you. The manufactures of ELT's provide instructions based

on  facts and service (crash) history.


	


   And when did I say any such thing? What I said was that

   every manufacturer of a product has his/her wish list

   of things you should do to optimize the performance of his/her

   product. Your ABILITY to comply with all those wishes is limited

   by the particulars of your installation and one seldom

   finds it possible to comply with ALL the manufacturer's

   wishes.



   The notion that the ELT manufacturer did anything based on

   service history (other than fixing failures) is wishful thinking.

   ELTs, like all other black boxes on TC aircraft are built to

   specifications written by folks who almost never have any

   experience in the manufacturing venue. The specs are then blessed

   by a cadre of bureaucrats who have some knowledge of crash

   history but only a few understand what they know. The golden

   idea is that if Tonka Toys decides to get into the ELT business

   and they've been ISO 9000 qualified, then all the have to do

   is jump the intermediate hoops and meet the spec and all will

   be right with the world. The idea that most manufacturers

   have a nervous system that extends to the far reaches of

   their customer's experience base is wishful thinking.



 	  Quote: 	
		  

   I partially agree with you, not to lose sleep and often the ELT

installation instructions can't be fully met on some small planes.



However to say:



   *deviations..MOST have no major contribution to the outcome

of ANY crash/recovery scenario*  is shooting from the hip.



   MOST? ANY? Have proof? Data? Define, what is a deviation?


	


    A deviation is anything which does not fully comply with

    the manufacturer's recommendations . . . which are often

    sufficiently vague as to defy any quantification as to

    cause/effect or cost/benefits.



    Knowing what I've learned and come to understand about

    over the years about transmitters, receivers, antennas,

    patterns and propagation  efficiencies, I was NOT shooting from the

    hip. Each communications link is first designed with

    head-room for uncontrollable losses due to atmospheric and

    physical conditions. We know that NO ELT antenna installation

    on an aircraft can be ideal, especially small aircraft.

    Therefore, worries as to exact placement are pointless.

    As I mentioned, it's more important that the antenna SURVIVE

    than for the antenna to be 100% effective with respect to

    ideal conditions.



 	  Quote: 	
		  

   No offense, flying over Kansas or what ever flat state you're in,

is not like flying over wilderness in the Western half of the US,

Canada and Alaska, I am glad to have an ELT installed per

manufactures recommendations.



   ELT manufactures might know something, you think Bob?


	


    Yup, they USUALLY know everything there is to know about

    their product (until the guy who designed it retires or

    gets a better job, then big chunks of tribal-knowledge

    goes out the door with him).



    But they have limited understanding of the situations in which

    their product will be used . . . there are simply too many

    variations on a theme. Hence, the broad brush, sweeping,

    generally non-quantified recommendations.



 	  Quote: 	
		  

My suggestion is try to comply as much as possible. I know if

you call the manufacture they can provide guidance solution

  (compromise). It will be more than it does not matter.


	


    Never recommended anything different . . . do the BEST

    you can knowing that even the manufacturer cannot tell

    you what effect "deviations" might have. They can only

    say that deviations generate risks to performance. Will

    your particular "deviation" reduce probability of being

    found by 50%, 1%, 0.1%? Nobody knows, ESPECIALLY the

    folks who make the ELT.



    I work with those folks George. I install and trouble

    shoot installations of their equipment. For the most part,

    when things are not going well their fall-back position

    is the same as for any other farmed-out black-box installed

    on a certified aircraft: "We meet the specs, we passed our

    acceptance test procedure, and our QA manual has been

    blessed by your QA police. Therefor, our product is golden."



    Translation: "Yes, we know how our box works but haven't

    the foggiest notion of how YOU might have screwed up

    in YOUR installation." In the recent case cited for

    ELT self-test trips, we DID screw it up.

 	  Quote: 	
		  

Please don't make this about you being right and me wrong.

This is about learning. A cavalier attitude is not appropriate to

the topic. Bob, you pride yourself in your facts and repeatable

experiments. I say the 1000's of crashes that the manufacture

and FAA have studied in developing the guidelines have merit,

period. If you have specifics than please say, but the general

dismissal of ELT manufactures recommendation as found

wishes is condescending.



   Bob you often have FONDEST WISHES for your ideas and

concepts, you claim are based on irrefutable logic and

experiments. I think you should give other professionals in

the aerospace industry the same professional courtesy and

respect for their expertise.


	


   Respect is not a right George, it must be earned. Many

   folks I've worked with over the years have my highest

   respect and confidence. Others in spite of their QA manuals,

   holy-watered PMAs and TSOed products would not be allowed

   to wash my dog. It's not that they're evil, have unsavory

   personalities, etc. They just don't understand and do

   not have a charter from their management to achieve

   necessary levels of understanding.



   It's the very rare manufacturer who understands both

   his product and its utilization well enough to be an

   effective assistant in solving problems. I've been doing

   this for 25 years George and I can remember only a hand-full

   of cases where the manufacturer of a mis-behaving product

   has been helpful in deducing and fixing root cause. The

   sum total of these situations have cost my employers

   tens of $millions$ . . . I can name you a half dozen

   situations right now that piddle away $millions$ a year

   on truly dumb wrestling matches between suppliers (them)

   and customers (us).



   But I never said that it wasn't a good thing to attempt

   compliance with the ELT manufacturer's instructions

   to the letter. What I did say was that your ability to

   fully comply was not only difficult but that the effects

   of your non-compliance are impossible to deduce. I'll

   suggest further that no fielded installation fully complies

   with the manufacturer's fondest wishes.



   Bob . . .

bruceflys(at)comcast.net
Guest

Posted: Mon May 29, 2006 10:51 am Post subject: ELT Antenna Placement

The April 2006 issue of Sport Aviation, the EAA's primary magazine, had a 

lengthy article on ELTs.  Here are some quotes:



[....with studies showing the false alarm rate is 99 percent.



[....with the older units failing to activate when intended two-thirds of 

the time.



[Evidence also suggests the units broadcast a satellite-useable post-crash 

signal only a tenth of the time.



[The new ELTs...digital transmitter broadcasts in bursts at 5 watts, a huge 

improvement over the 0.1 watt analog signal of the 121.5 frequency ELTs.]

So Bob has it right.  The ELT manufacturers and the FAA came up with a 

flawed system using 30 year old technology, which never worked as intended. 

Unlike some participants on this forum, they have learned from experience, 

and designed the new 406 MHz ELT system as a replacement.



Regards, Bruce McGregor

 	  Quote: 	
		  

 Please don't make this about you being right and me wrong.

 This is about learning. A cavalier attitude is not appropriate to

 the topic. Bob, you pride yourself in your facts and repeatable

 experiments. I say the 1000's of crashes that the manufacture

 and FAA have studied in developing the guidelines have merit,

 period. If you have specifics than please say, but the general

 dismissal of ELT manufactures recommendation as found

 wishes is condescending.



  Bob you often have FONDEST WISHES for your ideas and

 concepts, you claim are based on irrefutable logic and

 experiments. I think you should give other professionals in

 the aerospace industry the same professional courtesy and

 respect for their expertise.



  Cheers George ATP/CFII-MEI, B73/75/767

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