TM 3-6665-304-10
predictor until the GN line is pointing toward grid north of the map.
m. Evaluate the effect of fallout on tactical operations or plans. For operational purposes, the following rules of
thumb may be applied to the actual arrival of fallout:
(1) The actual arrival of fallout may occur as early as one-half the estimated time of arrival. That is, if the
estimated time of arrival of fallout is H + 4 hours, actual arrival of fallout may occur as early as H + 2 hours.
(2) If actual arrival of fallout has not occurred at twice the estimated arrival time, or 12 hours, whichever is
earlier, then it may be assumed that the area will not receive fallout. That is, if the estimated time of arrival of fallout in an
area is H + 4 hours and fallout has not occurred at H + 8 hours, then it may be assumed that the area will not receive
fallout.
7.
Special Cases
a. Low Winds. The situation may arise when the effective windspeed and direction cannot be reliably defined for a
particular yield. This occurs when the effective windspeed drops below 8 kilometers per hour and the winds are light and
constantly changing direction. In such cases, fallout may occur at almost any location around
2-6
