56-101-01200 Revision G
Page 11
C. Sufficient time should be allowed for the Sight Compass to stabilize before taking readings. It is
best to take a series of three readings before assuming that the readings are correct.
D. Normal procedure is to either taxi or tow the aircraft to approximately the desired heading as
read on the Compass to be compensated (within 5 degrees).
E. The operator using the Sight Compass, then standing directly in front of the aircraft and with the
Sight properly lined on the center line of the aircraft, observes the exact heading on which the
aircraft is positioned, and notes any error that exists between the Sight Compass and the
Aircraft Compass being compensated.
F. Whatever error exists between the Sight Compass and the Aircraft heading is then corrected by
moving the Aircraft the number of degrees difference existing until such time as the Aircraft
heading and the reading of the Sight Compass are corrected for the desired heading (within 5
degrees).
G. It is of the utmost importance that during the swinging procedure a minimum distance of 30 feet
be maintained between the Aircraft being swung and the operator using the Sight Compass.
Also, the operator and the Sight Compass must be a minimum of 50 feet from any other aircraft,
or at least 100 feet from any large building, power lines, or heavy objects which might cause
interference.
H. Insofar as possible, all fixed or movable items containing ferrous materials should be placed in
positions they will occupy in flight before beginning the swing.
I. The Compass should be inspected for general serviceability.
J. An Aircraft Compass is easily affected by stray magnetism from electrical circuits and moveable
steel objects. Before swinging the Compass, the aircraft should be positioned approximately
north, east, south, and west. On each heading, the Compass should be observed with the
engine(s) operating and indicating generator charging, and with the engine(s) stopped. If a
significant difference is observed, the swinging should be done with the engines running and
charging. Also, on each heading, various electrical components should be turned ON and OFF
to determine their effect on the Compass. A determination must be made as to what equipment
will be used during the Compass swing. In some cases, multiple readings may be required to
cover normal, abnormal, and emergency conditions.
K. When swinging the Aircraft, it should be kept (as nearly as possible) in the center of the chosen
area. Since it is easier to move the Sight Compass than the aircraft, it is not essential that the
aircraft be precisely positioned on the selected headings. However, the aircraft should be within
5 degrees of the desired heading for best results. Also, during the actual compensating
procedure on north, east, south, and west, the alignment should be as close to the exact
heading as practical.
6. COMPASS COMPENSATION PROCEDURE
Note:
All these corrections shall be made using a non-magnetic screwdriver. The Compass
shall be lightly tapped after each adjustment and be allowed time to settle before taking
readings.
