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  #1  
Old 01-03-2018, 10:15 AM
jaustinmd jaustinmd is offline
 
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Location: Pikeville, TN
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Default Public ADS-B Performance Report Interpretation

Although there is a User's Guide published by the FAA to accompany the Public ADS-B Performance Report (PAPR), I still have difficulty interpreting my PAPR reports. Obviously, any parameter flagged red on the report is a problem, but I'm not sure what the FAA considers a "pass" when the total report is taken into consideration. NOTE: I'm NOT discussing testing for purposes of claiming an ADS-B installation rebate, but rather whether I have a basically satisfactorily-performing ADS-B installation or not.

Here's a specific example: I recently installed an ADS-B "out" device and have received at least two totally clean PAPR's with 0 errors in all parameter boxes. OK, that's great, BUT subsequent to that, I recently had a short flight (14 minutes) with a "Missing Elements" NACv error red-flagged (which I understand to be a GPS velocity parameter). It indicated a "13.55% Max Fail" with the maximum duration of the error (Max dT) of 1 min 48 seconds and 110 maximum consecutive failures (McF). All other parameters in the report had 0 errors.

However, earlier in the same report, it reported under "Exceptions" that NACv was "No," which according to the User's Guide, "No=Pass."

The User's Guide is confusing because on page 7 it states that a NACv Exception is whether the "aircraft failed to meet the performance standards of the identified parameter: Yes=Fail, No=Pass." Then, on page 8, where the Guide discusses "Missing Elements," it says "Missing Elements will be highlighted in red if the aircraft fails to meet the Performance Requirements."

So, am I to interpret that since there is no NACv Exception, that overall, this is a satisfactory/passing report? Does this mean that although the NACv parameter had a significant % error, the percentage was relatively high because it was such a short flight and therefore, not really of concern?

I'm hoping there's someone out there who is very familiar with these reports and can comment. If anyone can point me to a "plain-language" explanation of the PAPR reports and the significance or not of the various parameters, I'd really appreciate it!
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Last edited by jaustinmd : 01-03-2018 at 10:21 AM.
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  #2  
Old 01-03-2018, 10:42 AM
jaustinmd jaustinmd is offline
 
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Quote:
Originally Posted by rv7boy View Post
John, it's been a couple of months since I flew my test flight. In my case, and in many others, the FAA was very prompt in sending me an email explaining my test flight score. Since I did not fly in Class B or C airspace and did not communicate with controillers, I knew ahead of time that my report would be delayed. But my final "OK" for my flight came about a week later.

I'm sorry but I can't interpret your test scores, but I do believe if you'll wait a few days, the results will be in your inbox.
Just to be clear, I'm talking about submitting a request for a PAPR to evaluate my installation, NOT in conjunction with application for a rebate. I do very promptly receive an email with an attached PAPR report, but there is NO interpretation by a human - just parameters red-flagged if there are errors. I know you can request a review/"manual interpretation" by a "real person" at the FAA, but no interpretation is sent automatically. Even when I have requested a "manual interpretation," they indeed do state if it is "OK" or not, but really don't go into explanation of errors and typically say "contact your avionics manufacturer or installer."

I'm just trying to get a better understanding of what constitutes a "pass" or "fail" and what significance, if any, individual parameters constitute. I guess my basic question is that if there are no "Exceptions" in the report, despite individual parameters being red-flagged, is it a "passing" report? I'll see if I can ask that specific question on a manual review and see if the tech answers definitively.

Thanks,
John
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Last edited by jaustinmd : 01-03-2018 at 10:46 AM.
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  #3  
Old 01-03-2018, 10:47 AM
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rv7boy rv7boy is offline
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After re-reading your post, I realize I probably should not have replied. Thus, I deleted my post. Hopefully, someone can provide the assistance you are requesting. Sorry for the quick trigger fingers.
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  #4  
Old 01-03-2018, 01:11 PM
jaustinmd jaustinmd is offline
 
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Well, I emailed the PAPR for manual interpretation and here's the FAA's response:


The good news is the reports are easy to read because if there is red ANYWHERE that means the ADS-B system is not meeting performance standards (failure). However, there are exceptions and one is fringe of coverage due low altitude flying/mountains. In your case, it appears the red is due to low altitude (below 2000 ft) and lack of ADS-B coverage. I suggest you check the system again after a few more flights. It appears your system is functioning correctly.


His assessment is correct in that the flight started at low altitude (but, I've had 2 "perfect" PAPR's following the same flight profile). So, I guess one can't assume too much and has to request a manual evaluation anytime there is a failure to find out if it is significant or not! I certainly appreciate the FAA's prompt and personal response!
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  #5  
Old 01-03-2018, 03:12 PM
rv8ch rv8ch is offline
 
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Quote:
Originally Posted by FAA
... In your case, it appears the red is due to low altitude (below 2000 ft) and lack of ADS-B coverage. ...
Don't all flights start and end at low altitude? :S
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