(1) Before receiving the dose rate information, mark and label the checkpoints for the route on
the work sheet overlay and trace out the preselected route.
(2) After the survey data for the route are received, count the number of readings taken for the
route. Ensure that you include all readings, including zero readings, since the number of time intervals
used during the flight of the route is required. Since the aircraft flew over the route at a constant ground
speed taking readings at equal time intervals, the distance covered between any two consecutive readings
will be the same. Thus, if the route is divided into a number of equal length segments where the total
number of segments is equal to the number of time intervals, each division point on the route will
represent a location over which a dose rate reading was taken. The interval between readings is equal to
the length of the course leg or route divided by the number of readings less one as shown here:
Length of the course leg or route (km)
Number of readings 1
For example, Figure 6-1 shows the points along route (1) to (2) over which readings were taken. In this
case, seven readings were taken but the route is divided into only six segments. Therefore, divide the
route into a number of equal-length segments equal to one less than the number of readings taken by the
survey party (7 1 = 6).
(3) Post the normalized dose rates on the work sheet overlay beside the location point for the
route as the dose rate readings are processed.
6-4. Aerial Survey Course Leg Technique. Dose rate information from an aerial survey conducted by
the course leg technique is plotted using the same procedure as that established for the route technique.
The only difference between the two techniques is that in the route technique, the survey party proceeds
between two checkpoints over a feature, such as a road or railroad, whereas in the course leg technique,
the survey party proceeds on a straight-line course between the two checkpoints. The two checkpoints are
marked and labeled on the work sheet overlay and a straight line is drawn between them. The aerial
survey overlay shown in Figure 6-2 depicts course legs that were flown over an area predicted to receive
fallout. To illustrate the plotting procedures, assume that the course leg between preselected checkpoints
five and twenty is 5.25 km long. The aircraft flew at a constant speed of 90 kilometers per hour (kph),
taking readings every 15 seconds for a total of 15 readings. Reading number one would be plotted at
checkpoint five. The distance between readings is computed as
Aircraft speed (kph)
Distance between readings
x time interval (sec)
3.6 is a constant that is used to convert kph to meters per second (mps). Then mps multiplied by the time
interval (sec) equals the distance on the ground. Therefore, the course leg is divided into fourteen
segments of 375 meters. Reading number fifteen then falls on checkpoint twenty.
6-5. Distance Conversion Procedures. To plot survey data, it may be necessary to convert miles to
kilometers (km). To do this, you must multiply the distance in miles by 1.61. To convert kilometers to
meters, you must multiply kilometers by 1,000.
3 miles =
3 x 1.61 =
,, mile =
.805 km or 805 meters
.5 x 1.61 =