Navigation has been defined as “the business of conducting a craft as it moves about its ways“. This broad definition of navigation encompasses the whole process of handling, steering, control, guidance and operation of the craft in a safe and economic manner. Navigation has a much longer history than aeronautics. As man first began to explore the world and to develop trade, the need for safe and predictable operation of the craft was a spur to the application of the most advanced science and technology of the day.