iFly GPS Forum

Equipment: Navworx ADS600-EXP Grand Rapids Sport WS IFly720 with Beta Android Pad with IFly production Software ADS-B in wired serial connection to GRT and wireless to 720 and Android GRT encoder used as the altitude source for transponder and ADS-B I noticed that my display of traffic altitude did not agree between the GRT Efis and the Ifly. To confirm which was correct, I went up flying yesterday with several other planes and at the same altitude my GRT was displaying the correct altitude difference(-0) whereas the IFly was displaying -3 and the Android agreeing with the 720, displaying the altitude 300ft lower than mine. This difference between the IFlys and the GRT seemed to be consistent with all the traffic I was seeing. The ADS_B signal should be the same for both units, the only difference being direct wired vs wireless. Anybody else seeing this with similar setup? Vic Chewning

Yeah, iFly is not yet using baro altimeter info for correction. I'm told it's a feature that's coming.

But, I think it's more complicated than that. What altitude are we seeing for traffic? Some we are receiving via their ADS-B out on 1090. Others we are receiving via the FAA ground station on 978. Some of those have ADS-B out and others only mode C. We all know we should fly our airplane based on our altimeter, NOT GPS altitude. GPS altitude and your altimeter can vary by several hundred feet. I would never fly close to an unseen target that is less than 1000 feet differential from me.