ABSTRACT
Vertical navigation (VNAV) can be used to supplement or replace approach and landings using radio navigation aids; it can also be used to optimise the performance of the aircraft to reduce operating costs. Aircraft performance data is based on a number of factors including aircraft weight, altitude and outside air temperature. Since these factors are constantly changing, the task of calculating optimum engine thrust limits, aircraft speed and altitude has gradually been automated with the advent of digital systems. During the 1980s, lateral and vertical navigation functions were combined into a single system known as the flight management system (FMS). This chapter reviews the principles of FMS and explores some the key features and benefits. The flight management computer system (FMCS) calculates key performance data and makes predictions for optimum operation of the aircraft based on the cost-index.
