I know this old post keeps getting restarted. But it's the only one that seems relevant. My only problem is that when you go to calc VNAV it keeps putting Ground Speed along the entire route instead of IAS. So what happens when you activate it? It uses that number to auto adjust your AP when your AP is looking for IAS. Example: I was flying my A380 at .85 Mach and was already at cruise alt FL390. I entered my cruise alt (39000) into VNAV and hit Calc. It showed 510/39000 at each Cruise Alt waypoint. So each time I passed the next waypoint it auto set my Mach setting to over 1.15! (which would be the correct Mach number if 510 was IAS). I would be overspeed before I even realized it and would have to quickly disengage the AT, reduce throttle, set it again, and re-engage it. It's definitely a PITA (Pain It The...) So I had to manually edit each and every waypoint to read 270/39000 (which is .85 Mach at that Alt) in the VNAV and Activate and it worked fine after that. But why should you have to do that? I gave up and have come to the conclusion that I cannot use VNAV. :( I already know that the FS flight planner has it's bugs. If you click on NavLog it shows ground speed settings along the route instead of IAS. Obviously that is the problem. Does anyone know of a fix to this so that the Honeywell FMC imports the speeds properly? Note: Yes I have made sure it was installed correctly. Everything else works fine about it except that. I also tested it in several other airliners at different altitudes and speeds and it does the same.