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

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AFMAN 11-217V1 3 JANUARY 2005
title of procedure) published in FLIP that are retrievable from selected aircraft
navigation databases. USAF aircrews are authorized to fly these procedures as
an “overlay” in IMC provided it is retrieved from the database and underlying
NAVAIDS are installed, operational, tuned, and monitored.
9.14.1.3.9.1. Aircrews must verify the information in the database with the
published DP. The maximum allowable difference between the database
course(s) and published course(s) is ±5°.
9.14.1.3.9.2. In some cases, because of the software programming, there can
be tracking inaccuracies when flying non-RNAV/FMS DPs using an FMS.
These tracking inaccuracies have resulted in less-than-required air traffic
control separation and air traffic control intervention to prevent a possible
Controlled Flight Into Terrain (CFIT) accident. Non-RNAV/FMS procedures
often require navigational tracking over all the specified fixes. Many FMS
databases code the points in these procedures as Fly-by waypoints, instead of
Fly-over waypoints. Unlike an RNAV DP, which will specify on the printed
FLIP which waypoints are Fly-by and which are Fly-over, a conventional DP
will not make this distinction. Consequently, the FMS will lead the turn on
these points. This turn anticipation could result in a turn being started miles
prior to the expected turn point depending on the amount of required track
change, wind, and true airspeed. When verifying waypoints prior to flying a
non-RNAV/FMS DP using an FMS, aircrews must determine how the points
are coded (Fly-by vs. Fly-over) in their database. If there are large course
changes coded as Fly-by waypoints, the aircrew must be prepared to manually
intervene to ensure the aircraft tracks the procedure as published to remain
within protected airspace. This is permissible, as this is not altering the
waypoints retrieved from the database; it is insuring the navigation system
properly executes the procedure.
9.14.1.4. Certain segments of a DP 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. This is permissible, as this is not altering the waypoints
retrieved from the database; it is insuring the navigation system properly executes the
procedure. The database also may not contain all of the transitions or departures from
all runways and some GPS receivers do not contain DPs in the database.
9.14.1.4.1. Helicopter-only GPS departure procedures are to be flown at 70 knots
or less since turning areas and segment lengths are based on this speed.