Lesson 2/Learning Event 4
Techniques. The techniques used to conduct detailed aerial surveys include: (1) the route technique;
(2) the course leg technique; and (3) the point technique. In using the route technique, the pilot flies
between two check points, following the route of some predominant terrain feature such as a road that
connects the two check points (heavy dashed lines, figure 14 on page 55). In using the course leg
technique, the pilot flies a straight line course (course leg) between two check points (thin dashed lines,
figure 14). The procedure followed in obtaining dose-rate information between check points is the
same, using either the route technique or the course leg technique. When the dose-rate information
obtained from use of either technique is processed, the result is a series of ground dose rates spaced at
equal intervals along the path over which the aircraft was flown. The point technique is used to obtain
dose-rate information at selected points of operational concern and is normally employed to obtain more
precise information at those points than can be obtained by use of other aerial survey techniques.
Processed data from dose-rate information obtained using the point technique are ground dose rates
existing at each of the selected points.
Procedure for using course leg technique. The course leg technique requires that the aerial survey party
flies a straight line course (course leg) between two check points. The pilot maintains as nearly as
possible a constant height above the ground, a constant ground speed, and a straight flight direction
between the starting and ending check points of each course leg.
The pilot locates the starting check point of a course leg to be flown and either locates the end
check point or determines the azimuth of the course leg.
The pilot flies the aircraft on the proper course to pass over the initial check point on a straight
path to the end check point. When on course, he alerts the monitor and gives him the height
above ground. Shortly before reaching the initial check point, the monitor records the time and
height above ground for each course leg to assure proper operation.
The pilot commands "Mark" when the aircraft is directly over the starting check point, at which
time the monitor reads the survey meter, records the dose rate, and begins timing preselected
The monitor reads the survey meter and records the dose rate at each preselected time interval
(for example, every 15 seconds).
The pilot again alerts the monitor when the aircraft approaches the end check point When the
aircraft is directly over the end check point, the pilot commands "Mark." At this time, the
monitor reads and records the final dose rate for the course.