OK, so it's not one of those original posts that everyone seems to like, but FS isn't giving me original problems!Here's the itch:I'm at FL210 approaching KATL, at the height given me by ATC, with 30.12 as the altitude and all's well.Then ATC kindly informs me "...you are 300 below your assigned altitude. Please descend and maintain FL 210".Huh?1/ Why am I under FL210 when I have 21000 programmed in, and the altitude figure just quoted prior (30.12) is correct?2/ If I'm 300 below, why is it telling me to descend!!! When I went to school (a long time ago) descend meant 'go down'.3/ Off the tangent a bit, but I read on a post that in the US especially anything above FL180 is 29.92 hg. I'm not sure I understand why, but the question is why is MSFS telling me to use different figures about FL180?Any thoughts would be appreciated.ThanksTim

That has been happening to me quite lately. Not every flight, but every once in a while. I don't know what is wrong. Probably just a little bug. However if you do program into autopilot to descend the 300 feet ATC tells you to all goes well.

Hey Guys,I'm not the first one to say this, but you must remember that your altimiter should be set to 29.92 when you are above flight level 180 (18,000 feet). Below that, you are to utilize the given altimeter setting.John

Hi Tim, 2K2 is indeed programmed with US airspace rules. At FL180 and above all aircraft go to alt 29.92. This way all aircraft are at a known flight level preventing constant monitoring and flight level changes. ATC will still be giving you pressure changes in the area you are flying through which keeps you informed of weather fronts etc, but this would only be acted on if you drop below FL180. The 'descend' command is a little glitch. Sometimes ATC gets confused and doesn't know which way is up.(but you do):-lol This is by no means all inclusive of every flying 'rule of thumb', but in general will keep you and ATC happy. Hope it helps. :-wave

Thanks John, but if I'm above FL180, and it tells me to use 30.12 (for example), and I use 29.92, I'll get told I'm at the wrong height and I'll end up with the ever-popular "IFR has been cancelled" by ATC.Won't I?Guess I'll try it and see what happens.T

Thanks Brent.Oddly enough, this little 'glitch' has only started since I did a full defrag of my PC last week.Never seen it before now, and I've been doing this for a long time....