BenYou know, when I started this topic, I was looking for a simple explanation for something that I guessed I was doing wrong. I didn't realize that VNAV is so complex. It actually works out great for approaches and the like as I can program altitude and speed restrictions and it all works out just great.But I see now that VNAV is actually a pretty complex topic. So complex that even real-world pilots struggle to understand it. I find that amazingI intend to purchase that Mike Ray book at sometime in the not-too-distant future. Can I ask if it helped you to understand better how to fly the 747-400?

Hi, Yup, the book helps a lot (e.g. when to press to TO/GA button..), but don't expect it gives a very detail explanation or description of the aircraft. It is also very entertaining, a 747 manual that makes people laugh... ben

Ben / Kirk-Mike's books are magnificent- and I STRONGLY recommend them to the simmer who wants to learn and enjoy the complexity of PMDG's simulations fully.We have modeled the behavior of VNAV very very well. This has taken a significant amount of time and effort- and it operates as nearly flawlessly as the airplane itself.I have written a tutorial on the use of VNAV in a very complex approach to KLAX... Give it a try- as it will teach you how VNAV can make your life easier- and it will also give you an appreciate for how much work went into this part of the simulation!