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

AFMAN 11-217V1 3 JANUARY 2005 153
8.4.7.2. Normally, navigation north of 70°North latitude or south of 60°South
latitude is conducted with reference to true north or grid north. Specific procedures
vary greatly depending on aircraft type, avionics capabilities, and crew complement.
Unless otherwise annotated, where there is a reference to true north, the text also
applies in southern latitudes and applies to navigation with reference to grid
north/south.
8.4.7.2.1. There are areas officially designated Areas of Magnetic Unreliability
(AMU). Aircraft capable of displaying only magnetic heading are prohibited
from operating in designated AMUs. For areas north of 70°North and south of
60° South that are not officially designated as AMUs, MAJCOMs will
determine the highest allowable latitude for aircraft capable of displaying only
magnetic heading.
8.4.7.2.1.1. NOTE: Although partly south of 70° North, the entire Canadian
Northern and Arctic Control Areas and areas of Northern Domestic Airspace
are designated as AMUs.
8.4.7.2.2. MAJCOMs must provide aircraft-specific operational approval prior
to enroute and terminal area operations using navigation aids oriented to true
or grid.
8.4.7.2.2.1. Operational approval shall be based on development of aircraft
specific procedures and training. As a minimum, procedures and training
should address: identification of areas where reference to true or grid north is
required, procedures for displaying true or grid heading reference, procedures
for verifying magnetic variation information from the aircraft navigation
computer, procedures for inputting manual magnetic variation information,
procedures for returning to automatic magnetic variation computation,
minimum equipment requirements, and emergency procedures in the event of
true or grid navigation equipment failure while operating in the AMU.
8.4.7.3. Aircraft navigation displays must be set to display true north prior to flying
true headings or courses. Suitably equipped aircraft may also use grid reference if
applicable.
8.4.7.4. Outside of designated AMUs, aircraft unable to display true or grid
heading may use navigation aids oriented to true north for enroute navigation
provided procedures listed below are followed.