Specification :

Area Navigation ( RNAV) can be defined as a method of navigation that permits aircraft operation on any desired course within the coverage of station-referenced navigation signals or within the limits of a self contained system capability, or a combination of these.

RNAV was developed to provide more lateral freedom and thus more complete use of available airspace. This method of navigation does not require a track directly to or from any specific radio navigation aid, and has three principal applications:

1. A route structure can be organized between any given departure and arrival point to reduce flight distance and traffic separation;
2. Aircraft can be flown into terminal areas on varied pre-programmed arrival and departure paths to expedite traffic flow; and
3. Instrument approaches can be developed and certified at certain airports, without local instrument landing aids at that airport.

Navigation systems which provide RNAV capability include VOR/ DME, DME/ DME, LORAN C ( phased out in February 2010) , GPS, OMEGA ( no longer in use) and self contained Inertial Navigation Systems ( INS) or Inertial Reference Systems ( IRS) .