FCC 1.958
Revised as of September 1, 2021
Goto Year:2020 | 2022
```  §  1.958   Distance computation.

The method given in this section must be used to compute the distance
between any two locations, except that, for computation of distance
involving stations in Canada and Mexico, methods for distance
computation specified in the applicable international agreement, if
any, must be used instead. The result of a distance calculation under
parts 21 and 101 of this chapter must be rounded to the nearest tenth
of a kilometer. The method set forth in this paragraph is considered to
be sufficiently accurate for distances not exceeding 475 km (295
miles).

(a) Convert the latitudes and longitudes of each reference point from
degree-minute-second format to degree-decimal format by dividing
minutes by 60 and seconds by 3600, then adding the results to degrees.
eCFR graphic er13ap05.008.gif

(b) Calculate the mean geodetic latitude between the two reference
points by averaging the two latitudes:
eCFR graphic er13ap05.009.gif

(c) Calculate the number of kilometers per degree latitude difference
for the mean geodetic latitude calculated in paragraph (b) of this
section as follows:

KPDlat = 111.13209 − 0.56605 cos 2ML + 0.00120 cos 4ML

(d) Calculate the number of kilometers per degree of longitude
difference for the mean geodetic latitude calculated in paragraph (b)
of this section as follows:

KPDlon = 111.41513 cos ML − 0.09455 cos 3ML + 0.00012 cos 5ML

(e) Calculate the North-South distance in kilometers as follows:

NS = KPDlat × (LAT1dd − LAT2dd)

(f) Calculate the East-West distance in kilometers as follows:

EW = KPDlon × (LON1dd − LON2dd)

(g) Calculate the distance between the locations by taking the square
root of the sum of the squares of the East-West and North-South
distances:
eCFR graphic er13ap05.010.gif

(h) Terms used in this section are defined as follows:

(1) LAT1dd and LON1dd are the coordinates of the first location in
degree-decimal format.

(2) LAT2dd and LON2dd are the coordinates of the second location in
degree-decimal format.

(3) ML is the mean geodetic latitude in degree-decimal format.

(4) KPDlat is the number of kilometers per degree of latitude at a
given mean geodetic latitude.

(5) KPDlon is the number of kilometers per degree of longitude at a
given mean geodetic latitude.

(6) NS is the North-South distance in kilometers.

(7) EW is the East-West distance in kilometers.

(8) DIST is the distance between the two locations, in kilometers.

[ 70 FR 19306 , Apr. 13, 2005, as amended at  79 FR 72150 , Dec. 5, 2014]

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Goto Year: 2020 | 2022
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