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Sudden flight level change due to new pressure area


Jan Naslund
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Jan Naslund
Posted
Posted

Hi,

 

When the air pressure at the ground is high such as today (QNH 1030 - 1040 over Europe) and i making a flight from ESSA to EGLL. Approx 2 hrs 20 mins. I am cruising at FL380 on Standard QNH 1013 and I have experienced several times that suddenly my level changes from 38000 indicated on the altimeter to 37200 but also the other way around from 38000 to 38800. The drop in altitude is not so bad as the plane has to climb back up but when i am suddenly at 38800 my xplane 11 Zibo Mod dives at 5000ft /min to get down to 38000 again and if i am cruising at Mach .80 i am entering the never exceed speed range.

 

Because of this i am now cruising at .78 or .79 and when this happens i won't enter the Vne range.

 

I think this sudden airpressure change is due to that i am entering a new pressure area but so that can't be changed but is there any way of smoothing this out so that the climb/descent rate does not become crazy 4000-5000ft/min?

 

I know that part of the problem might be in the aircraft but i know from a few years ago when i was flying PMDG that there was a discusssion regarding this on Vatsim.

 

 

Best Regards / Jan

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Simon Kelsey
Posted
Posted

Hi Jan,

 

This will be a function of whatever weather engine you are using. In FSX/P3D, most decent engines smooth the wind and pressure changes and the registered version of FSUIPC has a feature that can smooth wind and pressure changes if the default weather is being used.

 

I have no idea whether there is something similar for X-Plane though!

Vice President, Pilot Training

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Jan Naslund
Posted
Posted

Hi,

 

Yes, I remember that FSUIPC had some setting for this. I have XPUIPC installed actually but i cant find any setting for this.

 

I have a popup menu in Xplane for XPUIPC but all i can change is XPUIPC performance settings , tune up , tune down. No idea what that is

 

Br /Jan

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Daniel Katz
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I have no experience with Xplane but in FS9/FSX I think the autopilot settings can be adjusted so you aren't suddenly diving at 5000 ft/min (setting may be in aircraft.cfg file).

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Jan Naslund
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Posted

Hi,

 

Not at the moment. I have xEnviro installed but I does not have it turned on because when flying on Vatsim, it can not depict the weather very good. For example there can be broken clouds at 200 feet and 600 meters visibility or it can be VV200 but with xEnviro and Vatsim weather it's CAVOK in the sim.

 

Flying offline xEnviro is ok though.

 

BTW, this happens approximately 5 times on a flight ESSA-EGLL with fairly even intervals and it's about 50/50 if the altimeter is going to show too low and want to climb or too high and want to descend.

 

Best Regards / Jan

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