406Mhz Homing

rescue520 · August 13, 2009, 08:54:48 AM

Hey From Aust again.
Had an interesting homing the other day.
We had to conduct a beacon homing on a 406mhz beacon without the 121.5mhz homing signal. I believe this was caused by the ELT being damaged.
We homed the 406 data signal to within 1nm of the elt.
How many of you have tried this? And how do you achieve this?
let me know
Rescue

♠SARKID♠ · August 13, 2009, 11:21:12 AM

And people said I was crazy for wanting to make 406 trackers for GTs

Al Sayre · August 13, 2009, 12:55:44 PM

Use a UHF low band Scanner and work off the signal strength, body blocking etc. Radio Shack has one for $99.00...

Airrace · August 13, 2009, 02:40:21 PM

I also would agree with Al Sayre buy a UHF low band scanner and use the body blocking method.

SarDragon · August 14, 2009, 12:55:01 AM

Are you talking about DFing the 406 MHz signal, or the low power 121.5 MHz signal? For the latter, most regular DF methods should work, once you acquire the signal. Tracking the former (the 406 MHz bursts), is difficult at best. You have a half-second burst every 55 seconds to try to acquire and get bearings on. Tell me your methods here.

rescue520 · August 14, 2009, 09:00:07 AM

yeah all we had was the 406mhz signal of the half second burst every 55 seconds. This homing was conducted Airborne in very hilly terrain mountain tops to 13000ft and the valleys down to sea level. We could only pick the signal up withing 10nm of the crashed aircraft. The way i homed this signal was using the becker sar df. I had to try and get the pilots to manouver the aircraft into the 10nm radius and time it with the 50second data burst. and had to remember which direction the becker pointed to and do this many many times untill we got a small enough area to send a helicopter into to visually find this aircraft. and as you can probably imagine the signal was bouncing off the valley walls everywhere.
Rescue

SarDragon · August 14, 2009, 07:06:56 PM

OK, you said the magic word - Becker.

SJFedor · August 16, 2009, 01:30:04 AM

Quote from: rescue520 on August 14, 2009, 09:00:07 AM
yeah all we had was the 406mhz signal of the half second burst every 55 seconds. This homing was conducted Airborne in very hilly terrain mountain tops to 13000ft and the valleys down to sea level. We could only pick the signal up withing 10nm of the crashed aircraft. The way i homed this signal was using the becker sar df. I had to try and get the pilots to manouver the aircraft into the 10nm radius and time it with the 50second data burst. and had to remember which direction the becker pointed to and do this many many times untill we got a small enough area to send a helicopter into to visually find this aircraft. and as you can probably imagine the signal was bouncing off the valley walls everywhere.
Rescue

Did you try just going to the SARSAT hits for the 406 hit? They're usually within half a mile of the target.

rescue520 · August 17, 2009, 03:44:10 AM

Yes, the SARSAT system was not detecting any 406 in the area. No one was detecting it, Our brief was to conduct a visual/IR search for a overdue aircraft. We were not briefed of anything to do with an ELT.
All i was asking is if anyone else has conducted a 406 homing on only the 406 data signal?

SJFedor · August 17, 2009, 05:24:43 AM

Quote from: rescue520 on August 17, 2009, 03:44:10 AM
Yes, the SARSAT system was not detecting any 406 in the area. No one was detecting it, Our brief was to conduct a visual/IR search for a overdue aircraft. We were not briefed of anything to do with an ELT.
All i was asking is if anyone else has conducted a 406 homing on only the 406 data signal?

IR search?

Never had to track a 406 just on the databurst. I'd think it would be pretty tough to do. But, if you had a databurst, did you try to read the data using the page on the becker that will read the databurst? Not hating on you at all, just asking some constructive questions.

And your best bet, instead of doing the burst hits "many many times" as you said, is to mark your position and direction and triangulate a search area. Then, narrow down farther from there.

rescue520 · August 17, 2009, 06:54:25 AM

Hey,
Yeah tried using the 406 data page to read it but all i was getting was a E2: cs/sync error. (But i get this with all other 406mhz beacons on other searches.)
Yeah IR = Infra red, We have a FLIR (foward looking infra red) Turret fitted to our aircraft (The Australian Dornier)
Sorry if i sounded a bit blunt i my last post i am always happy to answer any and all questions. i just wasnt seeming to get an answer for mine.
Thanks
Rescue
P.S im happy to answer any questions .

SJFedor · August 17, 2009, 07:11:16 AM

Quote from: rescue520 on August 17, 2009, 06:54:25 AM
Hey,
Yeah tried using the 406 data page to read it but all i was getting was a E2: cs/sync error. (But i get this with all other 406mhz beacons on other searches.)
Yeah IR = Infra red, We have a FLIR (foward looking infra red) Turret fitted to our aircraft (The Australian Dornier)
Sorry if i sounded a bit blunt i my last post i am always happy to answer any and all questions. i just wasnt seeming to get an answer for mine.
Thanks
Rescue
P.S im happy to answer any questions .

Oh! You're the guy from australia! Ok, now this make sense!

I've yet to have to track a 406 only on the databurst, however i've tracked a few 121.5's that were broken and only intermittently transmitted. I did a very similar method to what you did, with a few changes. I'd orbit one area until i started getting a signal, roll wings level and mark my heading, then get the bearing from the becker before it kicked out again, and plotted it on the sectional. Did this a few times and ended up with a pretty small search area (a triangle about 1.5nm on each side) and then just started intensifying the search inside that triangle, while getting one of our ground teams en route. That triangulation from the air was good enough to get the crew on the ground able to acquire the signal.

rescue520 · August 17, 2009, 07:21:32 AM

thanks for your response. yeah im the guy from aus.
The plotting on a chart did cross though my head but due to the tasking being a long way out of our usual area of operation we didnt have good enough charts to do so, so i had to do that in my head.....
Another question for you all, What sounds have you heard on the 406 data burst? From the numerous ones i have done all i have got was a burst of hash? I have tested the one on the aircraft and it seems to first send the data and then but a single beep? What have you experienced?

Thom · August 17, 2009, 06:02:31 PM

Quote from: rescue520 on August 17, 2009, 07:21:32 AM
thanks for your response. yeah im the guy from aus.
The plotting on a chart did cross though my head but due to the tasking being a long way out of our usual area of operation we didnt have good enough charts to do so, so i had to do that in my head.....
Another question for you all, What sounds have you heard on the 406 data burst? From the numerous ones i have done all i have got was a burst of hash? I have tested the one on the aircraft and it seems to first send the data and then but a single beep? What have you experienced?

I can't answer the additional questions about the Audio Signature of a 406 Data Burst (though I do want to hear from someone who can...), but I thought I'd point out a little lesson for everyone from your statement above:

QuoteThe plotting on a chart did cross though my head but due to the tasking being a long way out of our usual area of operation we didnt have good enough charts to do so, so i had to do that in my head.....

There's a lesson here folks, even in our slow prop planes, we can sometimes end up a great distance from where we intended to search. Extra charts are light, small, and relatively easy to carry in your bag until you need them. I always have decent to OK charts for everything within several hundred miles, Just In Case. Especially as we get into Hurricane Season for those in the South, covering your entire State, and possibly adjoining States is a very real possibility. Charts are cheap(ish) and small and light. Better to have and not need...

Thom Hamilton

rescue520 · August 18, 2009, 01:23:37 AM

i agree with you 100% charts are one of the most valuable things expecially when your out the area your familiar with.
On our aircraft we carry charts for the whole of australia and australian waters however we didnt carry any charts for international taskings like this one was. (trying my best to rectify this with the company now) When you think you have enought charts you will find youself needing more!

Thom · August 18, 2009, 04:03:12 PM

Quote from: rescue520 on August 18, 2009, 01:23:37 AM
i agree with you 100% charts are one of the most valuable things expecially when your out the area your familiar with.
On our aircraft we carry charts for the whole of australia and australian waters however we didnt carry any charts for international taskings like this one was. (trying my best to rectify this with the company now) When you think you have enought charts you will find youself needing more!

Actually, I'm impressed that you carry the charts for all of Australia! I can definitely understand why you wouldn't have charts of New Guinea or New Zealand on board at all times, especially if you don't get tasked with those International Assistance missions very often.

I also applaud you for trying to get the company to add those International charts. The better equipped you are, the better able you are to render aid to those in need. That should always be an easy sell on cheap(ish) things like charts.

Good Luck!

Thom Hamilton