Glider crash at Moriarty

121.5 mHz ELT: location accuracy 12000 meters

I'm not sure how to interpret this. An ELT (of any flavor) transmits a continuous signal, for as long as the batteries hold out. It can be received at a range much greater than 12 km, and can lead a searcher to within a few meters of the ELT. When an ELT signal correlates with a report of a missing pilot, a search commences promptly and continues until the crash site is located (or, possibly, until some time after the ELT signal quits).

I've been involved in 2 glider S&R missions for which a 121.5 MHz ELT signal was extremely valuable. In the first, the pilot crashed in a hard-to-access area and was killed on impact. He might still be there if not for his ELT, which continued to transmit until the crash site was located the next morning. (It's worth noting that a search - with its considerable attendant risks - continues whether or not the pilot has survived.)

The second was a successful search for a crashed (and seriously injured) glider pilot in another remote and difficult area. There's little question that his chance of survival would have been much lower without the ELT, which continued to operate for the 23 hours that he lay in the wreckage, in near-blizzard conditions.

The often-cited 50% rate of successful operation of 121.5 MHz ELTs deserves some explanation. According to an Air Force study, the four most common reasons for ELT failure a
1. Destroyed in crash
2. Destroyed in post-crash fire
3. Bad batteries
4. Improper installation
#2 should be very unlikely in a pure glider - and probably uncommon even in a motorglider. #1 and #4 can be addressed by proper installation in the area behind the cockpit, which tends to stay reasonably intact even in serious crashes. #3 is under the control of the aircraft owner. So a moderately careful glider pilot can expect his ELT to perform properly at a rate much higher than average.

AFIK, searchers an hour or two after the crash could find no SPOT, FLARM or ELT signal.

It's my understanding that all the electronics on the glider were destroyed or disabled on impact, but this will only be known for sure after the final investigation.

Mike

On Wed, 17 Jun 2015 14:54:37 -0700, John Good wrote:

121.5 mHz ELT: location accuracy 12000 meters

I'm not sure how to interpret this. An ELT (of any flavor) transmits a
continuous signal, for as long as the batteries hold out. It can be
received at a range much greater than 12 km, and can lead a searcher to
within a few meters of the ELT.

I took that as how accurately the old satellites could locate a 121.5 Mhz
signal. Took several orbital passes.

On Thursday, June 11, 2015 at 10:56:44 AM UTC-7, danlj wrote:
Let's cut through the fog and quit kvetching about irrelevancies such as CAP arrogance.
406-mHz ELT or PLB: location accuracy 100 meters
ELT cost: $650+
PLB cost: $250+
(If you can afford to fly, you can afford one)
121.5 mHz ELT: location accuracy 12000 meters
ELT cost: your life

If you don't put a GPS-equipped 406 mHz ELT in your aircraft or PLB on your straps, don't complain about the CAP, your spouse, or God when you're lying broken and cold and in pain in the wreckage. Blame yourself.

References:
http://www.sarsat.noaa.gov/406vs121.pdf
http://en.wikipedia.org/wiki/Distress_radiobeacon
http://www.sarsat.noaa.gov/emerbcns.html

As other are pointing out the "121.5 mHz ELT: location accuracy 12000 meters" comment has no meaning. This is an old accuracy number from SARSAT/COSPAS Doppler ranging. But since SARSAT/COSPAS no longer monitors 121.5 MHz beacons at all the accuracy has no meaning. And the fact that it is not SARSAT/COSPAS monitored it the main reason you don't want to rely on just a 121.5MHz ELT. 121.5 is still monitored by airliners, etc. and can be homed to high precision (but that needs time) by just about every SAR organization. All 406Mhz ELTs and PLBs also include a 121.5Mhz beacon to make detection of and homing by SAR teams easier... which is important to remember, if you think a glider is down and they have any type of ELT or PLB you want to be checking 121.5 Mhz. PLBs (but not ELTs) in the USA also have more code "P" (dit dah dah dit) added to that beacon (that was an FCC idea to try to filter the expected onslaught of idiot consumers activating PLBs, but which did not happen...maybe because idiot (and smart) consumers brought SPOT and InReach devices instead :-)).

The issues with ELTs are they are hard to properly mount in a glider, hard to actually test (you can't drop the glider on the ground from height, break the glider in pieces, tip it on it's side and then see if the ELT actually worked and provided a good RF signal), and just do not reliably activate at all even in GA aircraft, let alone gliders. I think the ELT or PLB is best seen as an important/very useful back-up for InReach or Spot. And I'd do everything I could using modern technology to reduce any reliance on the weekend warriors in CAP... which today would start with InReach, high rate tracking and a savvy/well informed ground crew/club/FBO etc. with an agreed plan in case of concern/distress/loss.

Anyone out there managed to install a 406 ELT on a standard category C of A glider with the proper paperwork from the maintenance shop? Just wondering because they all seem to have specs for ground plane dimensions that are incompatible with non-metal gliders. The Kannad referred to earlier specifies a minimum antenna ground plane radius of 24 inches for example.

On Friday, June 19, 2015 at 12:52:41 AM UTC-7, wrote:
Anyone out there managed to install a 406 ELT on a standard category C of A glider with the proper paperwork from the maintenance shop? Just wondering because they all seem to have specs for ground plane dimensions that are incompatible with non-metal gliders. The Kannad referred to earlier specifies a minimum antenna ground plane radius of 24 inches for example.

OK I'll play along, what would the "proper paperwork" be here? It should usually be a minor modification, installation of stand alone stuff, not required by regulation in a glider, and with installation requirements not provided for by any regulation. AFAIK the usual "required paperwork" would be a note in the maintenance log.

There is nothing really unique about a 406 MHz ELT... it's the 121.5 MHz beacon withing the 406 MHz ELT that gives the large ground plane and/or plane/awkward large antenna mounting requirement. Almost all installs of any type of ELT I've seen in gliders suck, especially the antenna location/distance from obstructions, ground plane etc.

Please give me the reference in the federal regulations that allows for a ELT to be installed as "stand alone stuff". That would be a valuable reference as we have been filing 337's

Lane

I suspect you are one of few A&Ps who would file a 337 for an ELT install in a glider. There is no regulation that I am aware of that controls an ELT install in a glider or clarifies explicitly if an ELT install must be a major or minor install.... You have to make that call. In your case does the FSDO actually look at anything about the ELT performance? Antenna? Ground plane? ELT install orientation? switch location? Look at compliance with the install documentation? (Some of which will be mighty hard to meet).

On Friday, June 19, 2015 at 9:34:03 AM UTC-7, Darryl Ramm wrote:
I suspect you are one of few A&Ps who would file a 337 for an ELT install in a glider. There is no regulation that I am aware of that controls an ELT install in a glider or clarifies explicitly if an ELT install must be a major or minor install.... You have to make that call. In your case does the FSDO actually look at anything about the ELT performance? Antenna? Ground plane? ELT install orientation? switch location? Look at compliance with the install documentation? (Some of which will be mighty hard to meet).

And to add to that ACK for example promotes the instal of their ELTs being minor installs, e.g. see the FAA letter here http://www.ackavionics.com/pdf/E-04%...all%20Data.pdf Of course there can be cases where it could need a 337.

On Friday, June 19, 2015 at 9:34:03 AM UTC-7, Darryl Ramm wrote:
I suspect you are one of few A&Ps who would file a 337 for an ELT install in a glider. There is no regulation that I am aware of that controls an ELT install in a glider or clarifies explicitly if an ELT install must be a major or minor install.... You have to make that call. In your case does the FSDO actually look at anything about the ELT performance? Antenna? Ground plane? ELT install orientation? switch location? Look at compliance with the install documentation? (Some of which will be mighty hard to meet).

And to add to that ACK for example promotes the instal of their ELTs being minor installs, e.g. see the FAA letter here http://www.ackavionics.com/pdf/E-04%...all%20Data.pdf Of course there can be cases where it could need a 337.