Flight management systems

The term ‘navigation’ can be applied in both the

lateral and vertical senses for aircraft

applications. Lateral navigation (LNAV) is

effectively the area navigation function described

in Chapter 16. Vertical navigation (VNAV) is

concerned with optimising the performance of the

aircraft to reduce operating costs. This has been

traditionally achieved by the flight crew

(particularly the flight engineer) making reference

to data contained within charts, tables and

performance manuals.