MARKING OF COMPASS SWINGING BASES
General. Compass swinging bases for alining
a. A minimum distance of 275 feet will be
aircraft for the precise calibration of all types of air
provided from the center of the compass-swinging-base
navigation equipment will be marked as shown in figure
pad to the nearest: :
-Significant quantity of iron.
-Parking area or hardstand for aircraft, vehicles,
Magnetic effects. Because of the calibration
operation involved, the compass-swinging base will be
-Taxiway, or engine runup.
located in an area of the airfield or heliport where local
b. A minimum distance of 100 feet will be
magnetic influence is at a minimum to preclude inherent
provided from the center of the compass-swinging base
deviations that would destroy the accuracy of the
to a 67 kilovolt or less power transmission line.
Consideration will be given to the necessity for greater
swinging base will not be placed in proximity to power
separation in order to avoid adverse influence from
transmission lines or concentrations of underground
power transmission lines in excess of 67 kilovolt.
conduits or pipe, railroads, or rail sidings, automobile or
aircraft traffic, buildings containing ferrous metals, or in
Marking with paint. Initial marking and re-
areas containing natural magnetic disturbances. Each
marking of compass swinging bases should be done as
location for a compass-swinging base must be checked
soon as possible, subsequent to the required curing
by a magnetometer to insure that the area has negligible
Re-marking existing marks should be
magnetic characteristics regardless of adherence to the
accomplished as often as necessary. The effectiveness
above criteria and magnetic limitations specified in
of markings is heavily dependent upon their proper
Military Standard MIL-STD-765.
maintenance to provide maximum contrast with
backgrounds. Compass-swinging bases will be painted
Pavement grade. The compass-swinging-base
with white nonreflective paint that conforms to paragraph
pad will be level in all directions. The grade of the
connecting taxiway and shoulder areas associated with
this facility will be in accordance with criteria given in TM
Application of paint. For application of paint
see paragraph 2-2b.
Alinement markings. The compass-swinging-
base pad will be marked with precision alinement
indicators accurate to within 0.25 percent of 1 degree.