Good day to you all.I have a problem. Every time when I want to use the VNAV I have a message on the FMC:Perf/VNAV Unavailable.What I tried , to use iton the ground, in the air, later on in the flight etc. I cant use it.There is no problem with LNAV.Oh........what do I wrong or what can I do to solve the problem.The first 2 or 3 times, when I used the program there were no problems.Thanks in advance .Henk [email protected] :(

Hi Henk,Do you have FS2Crew installed?I might suggest also asking the PMDG forum.Cheers,