The area marked Zone I is the Zone of Immediate
Operational Concern. In this area, exposed,
unprotected personnel will receive the maximum
allowable emergency risk dose of 150 centi-grays (rads)
of radiation in a time period from 0 to less than 4 hours
after the arrival of fallout. The 4-hour figure is an
estimate of how long it would take to pack up essential
ground force military units (equipment and personnel)
and evacuate an area as an intact and effective fighting
force. Essentially, Zone I must be evacuated before a
strike occurs, or the military units in the areas will suffer
high personnel casualties and extensive loss of
equipment and supplies.
The area marked as Zone II is the Zone of
Secondary Hazard. Exposed, unprotected personnel
may operate in this area between 4 hours and 24 hours
after the arrival of fallout before receiving 150 centi-
grays (cGy) of radiation. Essentially, military units in
this area have the necessary time to pack up and
evacuate after the arrival of fallout and remain effective
as a fighting force.
Outside of Zone I and Zone II, some fallout will be
received. However, military units may continue
operating for up to 24 hours and be expected to receive
less than 50 cGy radiation, and to operate for indefinite
periods of time without receiving more than 150 cGy
To construct a NATO fallout diagram, follow these
1. Locate ground zero (GZ) and mark it on your
2. Draw the radial lines. Using information in a
NAV NBC 3 NUC or NBC 3 NUC message, draw a
straight line extending from GZ toward the directions
indicated for the left and right radial lines. These
directions are measured clockwise from true north
when measurements are in degrees, or clockwise from
grid north when measurements are in mils.
Using information in the TESS RADFO output or
an Effective Downwind Forecast, plot a line extending
from GZ representing the Effective Downwind
Direction. Then, plot the radial lines extending from
GZ at 20° or one-half of the expansion angle right and
left of the EDD line.
3. Draw the cloud radius. From the NBC 3 NUC or
TESS output, determine the cloud radius. When using
an Effective Downwind Forecast, obtain a representa-
tive cloud radius for the appropriate yield group from
the table provided on the Ships Fallout Template (fig.
5-6). Use a compass to set the radius on your charts
latitude scale (1 minute of latitude is 1 nautical mile) or
grid scale, and draw the circle around ground zero.
4. Draw the Zone I boundary. TESS output: Set
your compass to the Distance to Zone I using the
latitude scale. NBC 3 NUC message: Set your compass
to the Effective Downwind Distance, also using the
latitude scale. Effective Downwind Forecast: Use the
nomogram shown in figure 5-7, the actual weapon yield
(or the maximum weapon yield if plotting a yield group
for planning purposes) and the effective downwind
speed provided by the forecast to calculate the Zone I
downwind distance. Set the compass to this distance.
With the compass point at GZ, draw an arc extending
between the left- and right-radial lines. Use a
straightedge to draw lines tangent to the cloud radius
circle and the point of intersection of the radial lines and
the Zone I boundary arc. Label the entire area within the
cloud radius circle, the two tangent lines, and the Zone I
arc as ZONE I.
5. Draw the Zone II boundary. Double the Zone I
downwind distance, and draw a second arc between the
radial lines. Label the area enclosed between the radial
lines and the Zone I and Zone II boundaries as ZONE II.
6. Draw the fallout arrival time arcs. The Effective
Downwind Speed is the distance traveled by the fallout
in 1 hour. Set your compass to the appropriate distance,
place the compass point at GZ, and draw a dashed-line
arc over the fallout plot. Label this line as H+1, for the
arrival of fallout 1 hour after detonation. Double the
distance on the compass and draw a second arc across
the diagram. Label the second arc as H+2. Higher yield
weapons may need an H+3 arc. The effective
downwind speed can also be determined by using the
nomogram shown in figure 5-7.
7. When the effective downwind speed is less than
8 KPH (5 knots), the predicted fallout areas of Zone I
and Zone II will be drawn circular around ground zero.
8. Finally, label the plot with the weapon yield, the
date-time of the attack (or the valid period of the
Effective Downwind Forecast), the location
coordinates or name of the location, and the effective
downwind speed and the UTC time (observation time of
the upper winds used in the fallout prediction).
The NATO fallout plot (for any scale chart) can also
be constructed by using the Ships Fallout Template
(fig. 5-6) or the three Land Fallout Templates that come
with the ATP-45. The templates are transparent plastic
diagrams with perforated holes used to place guide