BY ORDER OF THE SECRETARY OF THE AIR FORCE AIR FORCE ...

138
AFMAN 11-217V1 3 JANUARY 2005
NOTAMs, holds precedence and the database may not be used to fly terminal area
or instrument approach procedures except as noted below.
7.13.5.3.1. In some cases, waypoints in the navigation database may differ from
the charted instrument procedure. The differences listed below are acceptable and
do not preclude use of the database procedure.
7.13.5.3.1.1. Step down fixes depicted on the approach chart may not be
contained in the aircraft database. Pilots are responsible for ensuring
compliance with applicable step down fixes regardless of whether or not they
are in the aircraft database.
7.13.5.3.1.2. The database may contain some waypoints (capture fixes, and a
point in lieu of a FAF for non-FAF overlay approaches) that are not depicted
on the approach chart.
7.13.5.3.2. For GPS overlay approaches, certain unnamed points and fixes
appearing on a chart are assigned a database identifier.
7.13.5.3.2.1. NOTE: These database identifiers should not be used for
pilot/controller communications or on flight plans.
7.13.5.3.3. Small differences may exist in distances between waypoints.
Differences less than 0.3nm are acceptable for GPS overlay approaches. For
stand-alone GPS and RNAV approaches, the maximum allowable difference is
0.1nm. If distance information varies by more than these tolerances, the
procedure shall not be flown.
7.13.5.3.4. Computation of the GPS final approach course is based on the station
magnetic variation retrieved from the aircraft magnetic variation database. Many
aircraft have a non-updateable magnetic variation database, thus will be almost
guaranteed to be different from actual magnetic variation. This will cause a
difference between the displayed GPS final approach course and the charted final
approach course in the IAP. The discrepancy between displayed and charted
magnetic variation will depend on discrepancy between aircraft magnetic
variation database (age of database) vs. magnetic variation upon which charted
approach course is based (date of magnetic variation survey). Variation between
charted final approach course in the IAP and the final approach course computed
by the aircraft should be no more than 5 degrees. If the two differ by more than 5
degrees, the procedure is not authorized.
7.13.5.4. Underlying traditional navigational aids must be monitored if available
for RNAV and GPS terminal area and instrument approach overlay operations. In
the event of discrepancy between RNAV and underlying navigation aids, crews
must revert to using underlying ground-based navigation aids.
7.13.5.5. Crews must be knowledgeable of system limitations and be ready to
manually intervene with RNAV or GPS equipment if necessary. Certain segments of
a missed approach, DP, or SID may require some manual intervention by the pilot,
especially when radar vectored to a course or required to intercept a specific course to
a waypoint.