I have flown the NGX since it cAme out pretty much. No problems what so ever. Within the last week I have been having problems with vnav. Whenever I engage the vnav it works fine until about 20000 fit and then it does a climb rate of about 250 a minute and can't hold aggisgned CLB speed. Once I finally get to cruise it can't hold the speed and does like 50 less then I put in.
Any suggestion are appreciated.