[Noah]

Suppose there is an overdue aircraft and somebody initiates SAR. VFR, No flight plan, no SPOT messenger, no APRS transmitter, no ADS-B, no radar advisories, squawking 1200, no ATC contact at all. However, the aircraft DOES have a Mode S transponder which encodes registration number (right?) with each radar return. Would this data be used to establish last known position as a start point for Search and Rescue??? Or is it not recorded or not made available to SAR?

 

[xavierm]

Yes

Yes, and they will start the search from the last known position. It still may take several days to find the aircraft. Learned the hard way over a year ago.

 

[Kahuna]

I do not know about modes S programming of the transponder. Mine has never been programmed. However, if you have ever been in "the system" before with that transponder and that mode S, then they coorelate your N number with the mode S serial code which is unique to your transponder and wallah, they have the connection for life, or atl least until you fly that unique tx serial against another N number.

 

[Walt]

The Garmin Mode S only needs your N# to generate your mode S code, no "programming" required. The Trig needs both N# and mode S code input to function, until you do that it won't work.

 

[Ironflight]

Actually, I recently found out that the Mode S code IS your N-number converted to a different form via an algorithm.

 

[Capflyer]

Good question. With a typical SAR it takes a day or two to get the NTAP data (radar tracks) then the need to find the "needle in the haystack" with all the recorded radar tracks that squawked 1200. So what you are really asking is will a particular 1200 squawked radar track also show the Mode S transponder code as well so it can be picked out? I'll find out for sure and report back.

 

[Ron Lee]

Good question. With a typical SAR it takes a day or two to get the NTAP data (radar tracks) then the need to find the "needle in the haystack" with all the recorded radar tracks that squawked 1200.

A day or two delay could be the difference between life and death. Sounds like using APRS or Spot can eliminate that delay as well as provide a reasonable search starting point.

Of course the SAR folks would somehow have to know about the APRS/Spot data.

 

[Kahuna]

This is an interesting thread.
My 330 was bought new in box. Never programmed to my N Number.
The 330 needs to be programmed.
I just went and checked my programming and it was full of 1's in the N-Number. Book says it should come up on first boot with a message to program it and should keep coming up until a valid number is put it. I have never put anything in it.

My FAA registration on line shows a set of numbers, which I never sent them, nor know what to do with. It may the the algorythm, but I doubt it.

At any rate, thread made me program my 330 with my N-number.
No controller has ever said anything about it. No telling what if anything is on their screen for N-number and mode S relationship. I suspect no relation cause surely in all these years one bored controller might have mentioned it.

 

[SilverEagle2]

Every new Aircraft Registration (and I think old) have a Mode S identifier in there Registration whether you have a Mode S TX or not.

That group of numbers may be your N number converted per the algorithm. Once you put in your N number in your GTX330 it converts it and it should match that number on your registration when sent/broadcasted.

Then when you send the number in your data stream upon interrogation, they can match it to your registration.

That is how it was explained to me. Both the FAA and the TX manufactures have the magic decoder ring.

 

[aerovin]

I don't think that the aircraft ID function from a Mode S transponder is used for routine ATC services. Aircraft using the ATC system are assigned a ATC computer generated transponder code and subsequent radar data tags are associated with the entry made by the controller to identify the aircraft...thus the need to supply "N" number and aircraft type with initial ATC contacts. I would be surprised to hear if a Mode S radar system will provide any more information for SAR than the radar track and associated beacon code provided by the secondary radar data.

 

[Ironflight]

Every new Aircraft Registration (and I think old) have a Mode S identifier in there Registration whether you have a Mode S TX or not.

That group of numbers may be your N number converted per the algorithm. Once you put in your N number in your GTX330 it converts it and it should match that number on your registration when sent/broadcasted.

Then when you send the number in your data stream upon interrogation, they can match it to your registration.

That is how it was explained to me. Both the FAA and the TX manufactures have the magic decoder ring.

This is exactly how it was explained to me by a major avionics manufacturer - who builds a very popular mode S transponder.

I don't think that the aircraft ID function from a Mode S transponder is used for routine ATC services. Aircraft using the ATC system are assigned a ATC computer generated transponder code and subsequent radar data tags are associated with the entry made by the controller to identify the aircraft...thus the need to supply "N" number and aircraft type with initial ATC contacts. I would be surprised to hear if a Mode S radar system will provide any more information for SAR than the radar track and associated beacon code provided by the secondary radar data.

I was also told that this is the case - for now. The antique ATC computers can't produce an N-Number from your transmitted "Aircraft ID" becasue they don't have the software capability. This will presumably change with "NextGen", but for now, your anonymity is safe (unless you poke the bear, and they go pull tapes and run software offline...).

 

[Noah]

The antique ATC computers can't produce an N-Number from your transmitted "Aircraft ID" becasue they don't have the software capability.

This explains why I sometimes give my callsign and ATC flubs up a letter or two and I have to correct them - I figured with Mode S this wouldn't happen, but it obviously does, so I would agree from experience that they don't have READY ACCESS to my callsign information (or my aircraft type, because I recently had to convince a controller that it was ARRRVEEE, not ARRMY, LOL)!!!

 

[tkatc]

Not sure how the SAR missions work or what type of equipment they can use to locate an aircraft but I do know the ATC part of the equation. I can't tell if you have a mode A or S transponder (or Z for that matter). ATC does have different systems across the country but none of the equipment I've used or have seen at other facilities have such capabilities readily available at the controller workstation. Perhaps the equipment technicians have the capabilty to pull up additional information in the event of an accident or lost aircraft but the controllers do not.

 

[Jamie]

One advantage of mode S that I never see mentioned is it allows radar facilities to interrogate one airplane at a time. With mode C whenever your transponder receives an interrogation request it just replies in the blind. With mode S the radar facility can encode a mode s code into the interrogation requests and your transponder will ignore requests not intended for your aircraft.

This allows for much more accurate radar returns in congested airspace.

 

[blaplante]

406 ELT

Did I really read through this and no one mentioned the value of a 406 MHz ELT? With a GPS coupled 406 ELT it will report your last GPS position and registration info (you did register?) to the satellite system, which will be automatically sent to the AFRCC (Air Force Rescue Coordination Center). With that info we rarely have to launch a search airplane any longer - the coordinates are so good that we can have the ground team drive to your location and pick up the signal. This is all automatic... no need for you to press the button on your SPOT. When your registration contact number is called, and you don't answer, the searchers are called out. Assuming that the GPS location isn't in downtown "Big Town" (or right on airport KABC), everyone is going to presume that this is an actual and will expedite.

At the same time let me give a big thumbs down to your 121.5 ELTs. You may not have noticed, but the AFRCC no longer monitors 121.5. The only way 121.5 does you any good is if some passing aircraft reports hearing the signal *AND* ATC is bored enough to report that to AFRCC. Given that 99% of 121.5 signals aren't crashes... a lot of people just don't get very excited.

I also have to say that way too many people get reported missing at sundown. The problem with that is unless there is an electronic signal picked up we really can't do any useful visual searches until dawn. Bottom line - you better be prepared to overnight in place.

My credentials... multiple credited finds of 121.5 signals... not a single one was an emergency. The EPIRB on the derelict boat was especially memorable.