Aircraft Systems

7Short‐Range Radio Navigation

The navigation techniques discussed in Chapter 6 are for flights under visual meteorological conditions (VMC). Although accurate calculations with good weather forecasts can produce precise navigation without external references, in practice, the ground track has to be monitored to correct for errors in wind predictions. In addition, without external guidance, lining up on a runway and landing requires visibility with the ground. Since the advent of aviation, the aim has been to make air transport weather proof and this requires methods of navigating safely without external visual references, that is, under instrument meteorological conditions (IMC). Apart from occasional local extreme climate phenomena, all‐weather global aviation has been available for decades. In this chapter, the radio navigation systems that provide navigational guidance for ranges up to around 100 nautical miles will be described. These are important in the departure, approach, and landing phases of a flight and are integrated with global navigation systems such as inertial guidance and global navigation satellite systems (GNSS) that are used enroute. Thus, GNSS or inertial guidance brings an aircraft to an “initial approach fix,” defined by radio navigation beacons close to an airport. These are then used by pilots to follow tracks defined by the local beacons that align the aircraft with the runway and then, in the case of larger airports the aircraft is guided horizontally ...