Hello all,First, I must say what an excellent bunch of products you have, and I can't wait for the 747, MD-11, and the hinted 777. In fact, I finally made the plunge and bought FS9 simply because of the 747.Anyways, on to the problem I've been having - with PMDG 737-600/700.When flying around on VATSIM, I commonly get "cross XXXXX at XX thousand, XXX knots", or maybe I will be assigned a profile STAR, like the CIVET4 at KLAX (which has crossing restrictions at its various waypoints).Seeing how I'm often many, many miles away from the crossing restriction, I just change the MCP alititude to it, insert it into the FMC, and wait. But, when I reach the T/D, the engines will idle, and the descent appears to go normal. However, about a minute into the descent I get a "DRAG Required" message, so I pop up the spoilers, but even then I will often overfly the crossing restriction by as much as 2000-3000 feet. Even when I do make the crossing restriction on time I often have so much momentum from the wild descent that I'll bust the speed limit (including the omnipresent 10000/250k), which makes some ATC not too pleased.Thanks for any help,Peter

Peter,What you are experiencing is not bad VNAV calculations. It's the common problem "crap in, crap out"! ;-)Seriously. The FMC will not do the descent planning for you. It will however give you some invaluable tools. But you as the PIC always has the final call. If you suspect you will bust any limits. Well. Take more control and go V/S. This way you can control both your descent rate as well as your speed. Within certain limits of course. This is more important just before and below 10,000ft/FL100 as the limit for VNAV disconnect is much narrower here. Above 10,000ft/FL100 you can speed up to a couple of knots below Vmo/Mmo (the barberpole area) before VNAV disconnects. You can ignore the "DRAG REQUIRED" message in this case.Please bear in mind that this is a slippery bird. You can't expect it to slow down and sink at the same time. Plan to do either or. Actually that is what VNAV is planning. The green hollow circles you might see on the descent path is deceleration points. Also remember that VNAV PATH descents always will sacrifice speed for path. And the opposite goes for VNAV SPEED descents i.e. it will sacrifice path for speed. So if you have to be at a certain point at a certain speed and altitude your best bet is V/S.Another important thing to avoid "crap out" when using VNAV is to use the FORECAST page on the DES page. On this page you have to enter the aloft winds along your descent path. This will help the FMC to calculate an accurate top of descent (TOD)Do a search on the forum for this topic. It has been widely discussed over the years.Hope it helps,

I was just wondering, where can I get the winds aloft for my route when I'm flying online with vatsim. I'm not using activesky, so am I in trouble or??-Mikkel

Mikkel - If flying on VATSIM without any external weather it's pretty easy.All winds aloft are 000/00 i.e. winds aloft are not modelled in the VATSIM weather. At least this is how it used to be. And I doubt that has changed.If the winds aloft are indeed modelled, then real world data should be close enough as the VATSIM wx servers uses real world wx.A good page for winds aloft world-wide can be found here:http://weather.uwyo.edu/upperair/sounding.htmlHope it helps,

Thank you for the link. I'm not sure about VATSIM weather though. I seem to remember that while crossing the atlantic there were winds of about 40 kts.-Mikkel