This is largely academic due to the short distances involved, but... If you follow a constant compass bearing, you're not on a great circle path, you're following a rhumb line. For your Calgary-to-Toronto example, the great circle starts off at a bearing of 94 deg, but you need to adjust that along the way, so when you get to the destination, you're headed at 120.5 deg. The rhumb line is a constant 107.8 degrees the entire way. The rhumb bearing is calculated as follows:

my $bearing = atan2($lon2 - $lon1, aths($lat2) - aths($lat1));
sub aths { # atanh(sin(x))
   my ($x) = @_;
   my $y = sin($x);
   return 0.5*log((1 + $y) / (1 - $y));
}
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