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

AFMAN 11-217V1 3 JANUARY 2005 155
8.4.7.5.1. NOTE: Only VORs and TACANs can be oriented to true north.
NDBs cannot be oriented to true north. ADF needles always display relative
bearing to the station.
8.4.7.5.2. If your aircraft allows selection of true north as a heading reference,
select true north. No additional corrections are required for courses or headings.
8.4.7.5.3. If your aircraft does not allow selection of true north as a heading
reference, use the following procedures:
8.4.7.5.3.1. VOR and TACAN courses do not require correction for magnetic
variation.
8.4.7.5.3.1.1. The desired true course must be set into the CDI. The
aircraft CDI will indicate deviations left and right of the desired true
course. However, with magnetic heading displayed, the bearing pointer
will not point to the station, but will instead indicate true bearing to the
station. In other words, when established on course, the CDI will be
centered on the desired true course, but the bearing pointer will indicate
true bearing to the station and will be displaced from aircraft no-wind
heading by the amount of station magnetic variation. For example, the
Thule magnetic variation is approximately 60 degrees west. When
proceeding inbound on the Thule 180 degree radial true (360 course), the
aircraft no wind heading will be 060, while the bearing pointer will point
to 360. Be aware that this discrepancy between aircraft heading and
desired course may make flight director guidance unreliable.
8.4.7.5.3.2. All headings require corrections for magnetic variation.
8.4.7.6. For navigation using NDB, use the following procedures:
8.4.7.6.1. NOTE: Only VORs and TACANs can be oriented to true north.
NDBs cannot be oriented to true north. ADF needles always display relative
bearing to the station.
8.4.7.6.2. If your aircraft allows selection of true north as a heading reference,
select true north. No additional corrections are required for relative bearings.
8.4.7.6.3. If your aircraft does not allow selection of true north as a heading
reference, all relative bearings require correction for magnetic variation.
8.4.7.6.3.1. Crews should compute and fly the appropriate magnetic course
by correcting the desired true course for the magnetic variation at the
current aircraft location. Use the magnetic variation at your current
location. This correction should be updated at least every 5° of magnetic
variation or every 30 nm, whichever occurs first.
8.4.8. Minimum Altitudes.
8.4.8.1. Altitude Clearances. Ensure altitude clearances received en route do not
conflict with minimum en route altitudes (MEA), minimum obstruction clearance
altitudes (MOCA), minimum reception altitudes (MRA), or minimum crossing
altitudes (MCA) shown on en route charts.