Chapter 6
sufficient distance to satisfy the runway and taxiway lateral clearance distance and airspace criteria
discussed in Chapters 3, 4, and 5.
6.11.4. Siting Consideration.
6.11.4.1. Separation Distances. To meet the magnetically quiet zone requirements and prevent
outside magnetic fields from influencing the aircraft compass calibration, efforts must be taken
to make sure that minimum separation distances are provided.
6.11.4.1.1. Army and Air Force: See Attachment 11 for Compass Calibration Pad separation
distances.
6.11.4.1.2. Navy and Marine Corps. Criteria for separation distances for Navy and Marine
Corps compass calibration pad is given in MIL-HDBK-1021/1.
6.11.4.2. Preliminary Survey. During the site selection process, the proposed sites for compass
calibration pads must be checked for magnetic influences to insure that the area is magnetically
quiet regardless of adherence to separation distances. A preliminary survey as described in
Attachment 11 must be conducted to determine if the proposed site is magnetically quiet. A
survey, similar to the preliminary survey, must be conducted after construction of any new item,
building, within or near the separation distances of the pad. This will assure that the newly
constructed item has not created new magnetic influences in the magnetically quiet zone.
6.11.4.3. Magnetic Survey. The magnetic survey for the compass calibration pad is an airfield
engineering survey that is conducted at the completion of the pad to assure that the area is
magnetically quiet, to determine the magnetic declination of the area, and to layout the markings
for the pad. Engineering surveys are also required every five (5) years for Army and Air Force
compass calibration pads and every year for Navy and Marine Corps compass calibration pads.
This cycle is operationally important as the magnetic north not only varies at different locations
on the earth, but physically changes as a function of time. It is an operational requirement to
calibrate the aircraft's compass correction factor on a regular basis because of these changes in
the earth's magnetic pole. In addition, the magnetic survey validates that the compass
calibration pad is in a magnetically quiet zone; thus insuring proper compass calibration. The
magnetic survey for compass calibration pads should be performed in accordance with
Attachment 11.
6.11.5. Compass Calibration Pad Size:
6.11.5.1. Army and Air Force. Army and Air Force compass calibration pad size is shown in
Figure 6.24.
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