Typical commercial 3D CAD tools provide modal tools such as pan, zoom, orbit, look, etc. to facilitate freeform navigation in a 3D scene. Mastering these navigation tools requires a significant amount of learning and even experienced computer users can find learning confusing and error-prone. To address this we have developed a concept called "Safe 3D Navigation" where we augment these modal tools with properties to reduce the occurance of confusing situations and improve the learning experience. In this paper we describe the major properties needed for safe navigation, the features we implemented to realize these properties, and usability tests on the effectiveness of these features. We conclude that indeed these properties do improve the learning experience for users that are new to 3D. Furthermore, many of the features we implemented for safe navigation are also very popular with experienced 3D users. As a result, these features have been integrated into six commercial 3D CAD applications and we recommend other application developers include these features to improve 3D navigation.