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Baro Alt on ADS-B Performance Report

Piper J3

Well Known Member
Does anybody know the allowable value for Baro Alt Delta? I pass ADS-B Performance Report but usually have some small % of Baro Alt...
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Adsb

I’ve been fighting this battle with the FAA for months. My home airport is in a hole without radar coverage. ADSB doesn’t start working until 1,500 ft. AGL so the baro always fails if I depart from home airport, works fine otherwise. The FSDO doesn’t understand any of this. I’ve spent a lot of time with the manufacturer and they say my system is working as designed. Very frustrating.
 
Different Problems

I’ve been fighting this battle with the FAA for months. My home airport is in a hole without radar coverage. ADSB doesn’t start working until 1,500 ft. AGL so the baro always fails if I depart from home airport, works fine otherwise. The FSDO doesn’t understand any of this. I’ve spent a lot of time with the manufacturer and they say my system is working as designed. Very frustrating.

Your issue is a lack of correlation between UAT and Mode 3/A due to radar coverage; No mode3/A squawk reply - no ADSB out. This is fixable with a firmware update from Uavionix IIRC.

The Baro(D) issue is internal to the aircraft, Baro encoding indicating a problem from packet to packet.
 
Thanks guys...

The Baro(D) issue is internal to the aircraft, Baro encoding indicating a problem from packet to packet.

So, is this a problem I have to fix?
 
Some encoders take along time to warm up, and are erratic until they do.
Some, especially older encoders have poor resolution as compared to newer technology encoders. If your encoder has 100 ft resolution instead of 10 ft resolution (precision), then your ADS-B out messaging may show erratic baro delta.
 
It's a Garmin 327...

Should I check if 10 ft resolution (precision)?

I wonder how forgiving FAA is for Baro Delta? There must be some magical limit you can't exceed.
 
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