Plane sailing

Find course, distance and ETA from 23 January 2012 Noon  Lat 20º10’N Longitude 179º40’W to Lat 13º40’N Longitude 178º10’E with speed 13 kts?

Lat   20º10’N                              Long   179º40’W

Lat   13º40’N                              Long    178º10’E

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d’lat 6º30’ S                                d’long   2º10’W

= 390’ S                                      = 130’ W

m’lat  16º55’N

                                                                                               

cos m’lat = dep / d’long

dep = cos m’lat x d’long

      = cos 16º55’ x 130’

      = 124.37’                                                                           

tan course = dep / d’lat

                = 124.37 / 390’

                = S 17º41.2’ W

True course = 197º41.2’T                                                          

dist = d’lat / cos course

      = 390’ / cos 17º41.2’

dist = 409.3 nm                                                                       

Time = dist / spd

         = 409.3 / 13

         = 1d 7h 29m

23 Jan 2012      12h 00m 00s

1 day                   7h 29m 00s +

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24 Jan 2012      19h 29m 00s

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