Had a strange ALT readout at Gatwick (EGKK) yesterday and today.I am using Gary Summons (UK2000) Gatwick Pro scenery.If I enter the correct QNH as given by ASv6 the airport altitude is incorrect. From memory I think the QNH was 1022mb but if I pressed 'B' to reset the altimeter the pressure went to 1028mb.BTW the aircraft was the PMDG744.Anyone have any ideas?Dave

Hi,Is Foce Constant Route Pressure On?Hope this helps,Jimhttp://www.hifisim.com/Active Sky V6 Development TeamActive Sky V6 Proud SupporterHiFi Beta TeamRadar Contact Supporter

Force Constant Route Pressure was on because of crossing the Pond but I had not realised it affected dep & dest airport pressure.I have just tested with Constant pressure off and ALT reading is correct with QNH.Now the questions is, what pressure do I set to get a correct airport elevation reading?Should I leave Constant pressure off until I am airborne, use it just at cruise and then take it off on approach to destination, or what?TIADave

Hi Dave,It is going to be one of those trade-off issues. What that option does is, with a plan processed, and the option on, it sets all pressure to the departing pressure. I am not sure, but try this: Use the option On while crossing the pond and then turn it off. This may give you the best of both worlds.Hope this helps,Jimhttp://www.hifisim.com/Active Sky V6 Development TeamActive Sky V6 Proud SupporterHiFi Beta TeamRadar Contact Supporter

Thanks for the suggestion Jim.However "it sets all pressure to the departing pressure"If it does that then why is the ALT reading at my departure airport incorrect?For example I tested this evening at EGKK, ASv6 indicated 1016mb at EGKK but gave an incorrect airport ALT.Pressing 'B' set the altimeter to 1011mb and airport ALT was correct at around 200ft.Puzzled.Dave

Hi Dave,If you are at EGKK how far is the weather station? I am thinking that a nearby station is having an effect.Hope this helps,Jimhttp://www.hifisim.com/Active Sky V6 Development TeamActive Sky V6 Proud SupporterHiFi Beta TeamRadar Contact Supporter

Hi Jim,That could be the answer.Just run ASv6 with the EGKK - KBOS route again and the nearest reporting station is EGKB (Biggin Hill) which is 12nm away.However if I search wxstationlist.BIN it finds 'EGKK' which suggests that ASv6 has EGKK in its database, unless of course the above file is not just a list of WX stations but also includes associated airports.Don't worry too much as the number of TransAtlantic flights I do on line are limited and I can always try off line with force constant pressure off and see how the PMDG744 copes.Thanks for your help.Dave

Hi,Actually,That should read: "sets all pressure to the destination pressure"...We understand it would be desirable to have the departure pressure remain "unforced" so that local departure wx reports are correct, and we are working on trying to find a way to facilitate this without resulting in a possible large pressure jump at the departure stage.At this time it is recommended to use the destination report for proper altimeter setting.Best,

Hi Damian,>"sets all pressure to the destination pressure"...