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ADS-B No service list

texdog

Well Known Member
I operate out of a hole in ADSB coverage. The FAA knows it, but they won’t let go of the fact. FAA in Washington says take him off the list. It only fails when I leave home airport. No radar coverage below 1500 AGL. The aircraft fails baro for about 3 minutes. Has anyone else had this problem and how did you fix it? The Houston FSDO is the problem.
 
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It sounds like you have a UAT that ‘reads’ the transponder transmission? I thought the faa allowed UATs to substitute gps altitude (along with some code letter) when no transponder data was available? Call your adsb manufacturer.
 
Assuming you have all the updates and play by the rules, point the MFGR at your FSDO and vice versa.

No success, get political. First the airplane groups then the elected.

Everyone knew they built holes in the "network". They chose to not service you.
 
I operate out of a hole in ADSB coverage. The FAA knows it, but they won’t let go of the fact. FAA in Washington says take him off the list. It only fails when I leave home airport. No radar coverage below 1500 AGL. The aircraft fails baro for about 3 minutes. Has anyone else had this problem and how did you fix it? The Houston FSDO is the problem.

An aircraft should NOT need to be in radar coverage to provide full ADS-B Out including baro altitude.

If your UAT ADS-B Out device requires that the aircraft be in radar coverage so that your UAT can receive altitude data from your Mode C transponder, then there is something seriously wrong with your UAT.

Steve
 
If my aircraft was on the "No Services List", I would run a PAPR for my last flight (see https://adsbperformance.faa.gov/PAPRRequest.aspx), and then I would look at the items marked in RED, and refer to the PAPR User Guide (available here: https://adsbperformance.faa.gov/PAPRUsersGuide.pdf) to figure out what the exceptions/failures meant.

For example both a "Baro Alt" and "Mode 3A" would tend to indicate a problem with the Altimeter Encoder sub-system, and/or the UAT emitter instead of a coverage problem with ADS-B, although it's possible the Mode 3A fault is due to a fringe coverage area...

Just my $.02
 
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An aircraft should NOT need to be in radar coverage to provide full ADS-B Out including baro altitude.

If your UAT ADS-B Out device requires that the aircraft be in radar coverage so that your UAT can receive altitude data from your Mode C transponder, then there is something seriously wrong with your UAT.

Steve

I thought so too, but apparently not, as the faa has accepted UATs that ‘sniff’ the transponder signal to get the PA. But as I said, above, I thought they had to send a substitute, like gps altitude data.
 
I thought so too, but apparently not, as the faa has accepted UATs that ‘sniff’ the transponder signal to get the PA. But as I said, above, I thought they had to send a substitute, like gps altitude data.
Yes, you did indeed say that above.... Is there evidence you can show us that the FAA has been lenient in this manner? If that is the case, why would the manufacturer of one of these "sniffer" boxes have gone through the trouble of adding a separate baro pressure sensor to their box to allow it to "ride through" periods when the transponder is not being interrogated by ATC and still be able to provide pressure altitude in each ADS-B Out transmission?

It is very unlikely that this deviation is permitted as it would be in violation of 14CFR 91.227 which requires that the minimum ADS-B Out transmission include both barometric pressure altitude (d)(3) and geometric altitude (d)(14).

Steve
 
uAvionix

If the UAT is a uAvionix skybeacon/ tailbeacon/ echo, then a firmware update may be effective. The latest firmware update changes the way the UAT operates in areas of poor/ non RADAR coverage.
 
It is very unlikely that this deviation is permitted as it would be in violation of 14CFR 91.227 which requires that the minimum ADS-B Out transmission include both barometric pressure altitude (d)(3) and geometric altitude (d)(14).

Steve

Yes, I agree. Which is one reason I didn’t buy one of these sniffing units.
 
Longez;1513350why would the manufacturer of one of these "sniffer" boxes have gone through the trouble of adding a separate baro pressure sensor to their box Steve[/QUOTE said:
The rules are very clear that that is not allowed. Adsb and transponder must use the same PA source.
If you want my real opinion, I think this is just like the ‘two weeks to taxi’ programs. Someone at the FSDO level gave an erroneous okay, and now faa HQ doesn’t know how to put the cat back in the bag.
IIRC there was endless discussion here a few years back about exactly how these sniffer boxes were supposed to work if not within radar range. Don’t recall what if any answers there were.
 
The Airplane Flight Manual Supplement (AFMS) for this product discusses how the internal pressure sensor (encoder) is used.

Since it has no way of synchronizing the pilot entered squawk code with the transponder when the transponder is not being interrogated, it has this statement:

"In remote areas where you may not be interrogated by Secondary
Surveillance Radar, aircraft Mode A squawk code may be broadcast as
unavailable (0000)."

As far as I know, the Garmin GDL 82 is the only UAT that does it "right". When the transponder is on the ground or otherwise not being interrogated by ATC or a nearby TCAS aircraft, the GDL 82 uses its patented feature to interrogate the transponder directly and get the official transponder pressure altitude and squawk code as often as it needs to keep this data from going stale. Operating in this manner, the GDL 82 doesn't need an internal pressure sensor (something else to cause problems) or RS-232 wiring to a compatible transponder.

Steve
 
Fred
I had the same problem on my RV8 based out of 5C1, which is in the same low service area you are in.
Give me a call and I’ll tell you how I got it to work correctly and get a good PAPR.
Might work for you, too.
Steve
210 289 3984
 
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