Lesson 2/Learning Event 9
The locations for determining air-ground correlation factor data.
The time intervals between readings.
Whether to delay the flight of a particular course leg or route.
Guidance. As a guide to the survey party in making the determination discussed at the end of Lesson 2,
Learning Event 6 of this course, the tactical, operational, and weather conditions existing at the time of
the survey and the dose condition of the survey party should be weighed against the following factors:
The slower the aircraft speed and the shorter the time interval between readings, the more
accurate the results.
The unreliability of survey data obtained increases at heights of more than 150 meters above
the ground. A height of 60 meters is considered optimum.
The slow response time of the IM-174 series radiacmeter reduces the reliability of the data
obtained at ground speeds above 53 knots (98 kmph).
The combination of ground speed and reading time interval should be selected so that the
ground distance between readings is not more than 500 meters. For increased plotting
accuracy, at least 10 readings between check points are desirable.
Air-ground correlation factor data should be taken where aerial and ground dose rates can be
read most accurately on the survey meter, for example, in the dose-rate range of 5 to 10
cGy(rad)/hr.
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