COMPUTER NAVIGATION FIXES
An integral part of RNAV using en route charts
typically involves the use of airborne navigation
databases. Database identifiers are depicted on
NACO en route charts enclosed in parentheses, for
example AWIZO waypoint, shown in Figure 3-39.
These identifiers, sometimes referred to as computer
navigation fixes (CNFs), have no ATC function and
should not be used in filing flight plans nor should
they be used when communicating with ATC.
Database identifiers on en route charts are shown
only to enable you to maintain orientation as you use
charts in conjunction with database navigation systems,
Many of the RNAV systems available today make it
all too easy to forget that en route charts are still
required and necessary for flight. As important as
databases are, they really are onboard the airplane to
provide navigation guidance and situational awareness;
they are not intended as a substitute for paper
charts. When flying with GPS, FMS, or planning a
flight with a computer, it is important to understand
the limitations of the system you are using, for example,
incomplete information, uncodeable procedures,
complex procedures, and database storage limitations.
For more information on databases, refer to Appendix
A, Airborne Navigation Database.
HIGH ALTITUDE AIRSPACE REDESIGNHistorically in the U.S., IFR flights have navigated
along a system of Federal Airways that require pilots to
fly directly toward or away from ground-based navigation
aids. RNAV gives users the capability to fly direct
routes between any two points, offering far more flexible
and efficient en route operations in the high-altitude
airspace environment. As part of the ongoing National
Airspace Redesign (NAR), the FAA has implemented
the High Altitude Redesign (HAR) program with the
goal of obtaining maximum system efficiency by introducing
advanced RNAV routes for suitably equipped
aircraft to use.