B: 60ºN 140º30’W                                                                        A: 60ºN 120ºW

 

 

 

The great circle track at A is more than 270ºT

It is 270ºT + Conversion Angle = 270º + (½ x ChLong x sin mean lat)

                                                                                                                                    = 270º + (½ x 20½º x sin60º)

                                                                                                                                    = 270º + 8.9º    = 279º