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Are you using Developer Mode or made changes in it?
No
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Yes
Which aircraft are you reporting an issue about? (Please also add the proper tag for it)
Cessna Citation Longitude (but applies to all aircraft)
Which aircraft version are you experiencing this issue on? (You can find this listed in the Content Manager under the Aircraft Name)
Xbox, current MSFS 2020 build 1.38.2.0
Brief description of the issue:
I have finally discovered the source of a frequently reported bug - Traffic altitude is always reported on both TCAS and by ATC as being “off” from the expected 1000 foot increments (assuming level cruise using STD BARO above Transition Altitude). Traffic’s altitude from your plane is being calculated using your GPS Altitude instead of the Standard Barometric Altitude.
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Detailed steps to reproduce the issue encountered:
This screenshot from the Longitude was a few seconds too late, but I had 3 planes all about 40-50 nm away, all being reported at -62. I am at FL450 with STD BARO. I noticed that my GPS Altitude was 44165 (FL442).
If you subtract 6200 from my STD BARO Altitude of 45000 you would get 38800… an odd altitude for Traffic to fly at. Sure, it can happen with 1 plane, but after 2 years of flying MSFS, there is a pattern where ALL traffic will be reported as off by the SAME amount. So the Traffic altitude is not being calculated properly…
If you subtract 6200 from the GPS Altitude of 44200, you get FL380 - which makes sense. So if the Traffic is really at FL380, it should be reported as -70 relative to my FL450.
I have reported a bug in the past where I would fly at FL450, and ATC correctly knows I am at FL450 because if I descend more than 300 feet ATC complains… But at the same time, ATC will report MY altitude as something else (EG FL443) to another plane - obviously using the GPS instead of the Baro Altitude.
So I think it’s clear that the Traffic altitude is being calculated from your plane’s GPS altitude instead of its Barometric Altitude. Since all planes flying level above Transition should be on STD Baro this shoud be fixed. Even if the Baro is different a few miles away, as planes approach one another they will be at the same STD Baro (which is why STD Baro is used).
Some past reports never found the source…
https://forums.flightsimulator.com/t/atc-tcas-traffic-warnings-with-wrong-altitudes/616261
PC specs and/or peripheral set up if relevant:
Xbox X
Build Version # when you first started experiencing this issue:
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