Sec.  22.157   Distance computation.

   

   Link to an amendment published at  70 FR 19308 , Apr. 13, 2005.

   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 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.
   [MATH:  :MATH]

   (b)  Calculate  the  mean  geodetic latitude between the two reference
   points by averaging the two latitudes:
   [MATH:  :MATH]

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

   (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:
   [MATH:  :MATH]

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

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

   (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:
   [MATH:  :MATH]

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

   (1) LAT1[dd] and LON1[dd] are the coordinates of the first location in
   degree-decimal format.

   (2)  LAT2[dd]  and LON2[dd] are the coordinates of the second location
   in degree-decimal format.

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

   (4)  KPD[lat]  is the number of kilometers per degree of latitude at a
   given mean geodetic latitude.

   (5)  KPD[lon] 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) DIST is the distance between the two locations, in kilometers.