vPilot 3.3.0 Released

[Ross Carlson]

Version 3.3.0 of vPilot is now available. This version fixes the issue where MSFS pilots appear at the wrong altitude on ATC scopes and other pilots appear at the wrong altitude in MSFS, potentially causing TCAS alerts.

[Richard McDonald Woods]

Many thanks for all your efforts, Ross 😇

[Mike Teague]

ok now that i've seen this phenomenon twice in 2 days i thought i should report.. other aircraft appear to occasionally be getting "stuck" at/near  their origin airports in my sim even though they are long gone.

example: i just landed at kmia (aal1524) and dal8636 is still showing in my sim south of the airport (in a neighborhood?) even though in reality he is about 100nm northwest of miami.

yesterday i had a similar thing where someone was still showing on the ramp at katl when in fact they had just been handed off to jacksonville ctr

 

[Ross Carlson]

It's unlikely that is related to this change, which only has to do with altitude. See if you can catch me in the VATSIM discord when it's happening and I can take a look.

[Donald Stimson]

Ross,

Thank you for providing a fix to this complex issue. We have recently received a report from a user of our FBW A32NX in MSFS that he has gotten several TCAS alerts above the transition altitude where ATC is seeing a vertical separation of 1,000 feet, but the user is seeing TCAS vertical separations on the order of 300 feet. Our TCAS is using a relative altitude based on the true altitudes being reported by both planes (the other airplane through the traffic api and the own airplane from the MSFS simvar).

As I understand it, this Vpilot fix (for the MSFS client) adjusts the true altitude of the non-MSFS airplane to render correctly in MSFS, which has a more accurate representation of the true altitude of the airplane relative to its indicated altitude. An example you had provided in the MSFS forum a while ago addressed a case that was below the transition altitude. Based on this one user's report, might it not be fixing the issue above the transition altitude, where pressure altitude is being used?

There may be an additional issue here resulting from an incorrect standard day pressure vs altitude profile that was being used before one of the MSFS sim updates. This caused airplanes, when flying a flight level (i.e., baro set to std pressure), to be at an incorrect altitude for a given ambient pressure (which varied with altitude). Although MSFS fixed this error, the error would presumably still exist in P3D.  Could this lead to the issue this user is reporting?

[Ross Carlson]

5 hours ago, Donald Stimson said:

Based on this one user's report, might it not be fixing the issue above the transition altitude, where pressure altitude is being used?

The workaround I added applies to all altitudes, above and below transition.

5 hours ago, Donald Stimson said:

Could this lead to the issue this user is reporting?

I suppose so ... I'd have to know more details about the values involved.

[Donald Stimson]

Thanks for the quick response Ross. I don't want to waste your time if this is either due to a user error or an error in the A32NX TCAS system.

Regarding the original MSFS/FSX standard pressure vs altitude issue, there seemed to be two issues involved. One was an error in the profile itself (fairly minor errors at specific altitudes -- see attachment), while the other issue was improperly adjusting the pressure vs altitude relationship when the sea level pressure was not the standard day pressure. I have only one example at FL250. If the sea level pressure was set to standard (1013.25 hpa), the ambient pressure in MSFS was correct at about 376 hpa. However, if the sea level pressure was changed to 984 hpa, an airplane at FL250 in MSFS at that time was actually at an altitude where the ambient pressure was 362 hpa. This would equate to a pressure altitude of around 25,874 ft, an error of about 874 feet. I assume that issue would still be present in P3D. I have no idea what X-plane uses for an atmospheric model.

MSFS Pressure vs Altitude Plot.pdf MSFS Pressure vs Altitude.pdf