Western Hemisphere the sign is positive (+), and in the Eastern Hemisphere it is
negative (-).
Applying the proper sign to the number found by division yields the zone description
(ZD). Determining the standard time zone for Norfolk, Virginia would require dividing its
longitude, 76 18.0' W by 15, to yield a quotient of 5 with a remainder of 118'. Norfolk is
located in the +5 time zone and has the time zone indicator letter R assigned.
Time Signals
Time in the countries of the world is determined by national observatories, such as the
U.S. Naval Observatory in Washington, D.C. and the Royal Observatory in Greenwich,
England.
Station WWV at Fort Collins, Colorado and station WWVH on the island of Kauai in
Hawaii continuously broadcast signals based on Naval Observatory time. These
broadcasts may be heard with any ordinary radio receiver. Complete schedules and
information on Navy time signals are in the Flight Information Handbook.
ELEMENTARY PLOTTING
Plotting is the primary method of determining geographical position. Whether you are
working in Air Operations on an aircraft carrier or Base Operations at a shore facility,
the principles of plotting are the same. The information in this section is useful in almost
all phases of air traffic control.
Plotting Lines of Position
To understand how a fix or position is determined, you must understand what Plotting
Lines of Position (LOP) are and how they work.
A fix, or accurate position, can be obtained on a chart by finding a specific landmark.
When a NAVAID or RADAR is not used, each fix is established by two or more LOPs. A
LOP may be a visible line on the ground, like a highway or another object of known
position, but it is not visible until it is drawn on a chart.
For an example of how a LOP is obtained, suppose that an aircraft is flying visual flight
rules (VFR) over a railroad, but its location along the length of the railroad is not known.
If the railroad can be located on the chart, a line of position can be established. Then, a
second railroad that crosses the can then be located on the chart. The exact location of
the aircraft along the railroad is now known. Remember, a fix is an accurate position.
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