VansAirForceForums  
Home > VansAirForceForums

-POSTING RULES
-Advertise in here!
- Today's Posts | Insert Pics

Keep VAF Going
Donate methods

Point your
camera app here
to donate fast.

  #1  
Old 03-26-2021, 07:39 PM
texdog texdog is offline
 
Join Date: Jan 2013
Location: Fredericksburg, Tx.
Posts: 346
Angry ADS-B No service list

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.
__________________
T82 Fredericksburg,Tx.
Don't make easy hard!
Master Pilot Award
RV6A owner N6711
L19 sold
ATP/FE/CFI 10 Type Ratings.

Last edited by texdog : 03-26-2021 at 07:45 PM.
Reply With Quote
  #2  
Old 03-26-2021, 08:24 PM
BobTurner BobTurner is offline
 
Join Date: Dec 2011
Location: Livermore, CA
Posts: 7,356
Default

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.
Reply With Quote
  #3  
Old 03-27-2021, 05:53 AM
moosepileit moosepileit is offline
 
Join Date: Dec 2010
Location: Louisville, KY
Posts: 700
Default

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.
__________________
RV-6, bought from builder.
O-320, slider, carb, mags, FP
Reply With Quote
  #4  
Old 03-27-2021, 07:14 AM
Longez's Avatar
Longez Longez is offline
 
Join Date: May 2009
Location: KS
Posts: 196
Post

Quote:
Originally Posted by texdog View Post
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
Reply With Quote
  #5  
Old 03-27-2021, 09:21 AM
bjdecker's Avatar
bjdecker bjdecker is offline
 
Join Date: Jun 2005
Location: Georgetown, TX
Posts: 632
Default

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
__________________
Brian Decker
Retired Firmware Guy and Airplane Builder

2020 RV-14 QB -- Under construction - Tailcone & Empennage Complete.
2018 RV-7 QB -- Built, Flying
2007 RV-7 QB -- Built, Drowned, Resurrected and flying
1998 RV-8 QB -- Started, Sold
1986 Mooney 205SE
1980 Mooney 231

Aided and abetted building a number of other RV's.

Last edited by bjdecker : 03-27-2021 at 09:35 AM. Reason: Mode 3A...
Reply With Quote
  #6  
Old 03-27-2021, 11:37 AM
BobTurner BobTurner is offline
 
Join Date: Dec 2011
Location: Livermore, CA
Posts: 7,356
Default

Quote:
Originally Posted by Longez View Post
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.
Reply With Quote
  #7  
Old 03-27-2021, 12:58 PM
Longez's Avatar
Longez Longez is offline
 
Join Date: May 2009
Location: KS
Posts: 196
Post

Quote:
Originally Posted by BobTurner View Post
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
Reply With Quote
  #8  
Old 03-27-2021, 01:17 PM
OKAV8r OKAV8r is offline
 
Join Date: Feb 2007
Location: Seattle
Posts: 153
Default 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.
Reply With Quote
  #9  
Old 03-27-2021, 03:14 PM
BobTurner BobTurner is offline
 
Join Date: Dec 2011
Location: Livermore, CA
Posts: 7,356
Default

Quote:
Originally Posted by Longez View Post

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.
Reply With Quote
  #10  
Old 03-27-2021, 04:40 PM
BobTurner BobTurner is offline
 
Join Date: Dec 2011
Location: Livermore, CA
Posts: 7,356
Default

[quote=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]

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.
Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -6. The time now is 01:32 AM.


The VAFForums come to you courtesy Delta Romeo, LLC. By viewing and participating in them you agree to build your plane using standardized methods and practices and to fly it safely and in accordance with the laws governing the country you are located in.