Direction of Flight Given Lat and Long

[BCNAV]

Suppose I know the Lat and Long of an origin and destination airport. I then want to find the main direction of flight.

Example:

EIDW DUBLIN INTERNATIONAL
Lat: 53.4213888889 Long: -6.2700000000

TO:

CYYZ LESTER B. PEARSON INTL
Lat: 43.6767190556 Long: -79.6306582222

In this case I would like to return West. The reverse flight from CYYZ to EIDW would return East

Not sure SAS can do this or not. The preference would be only returning North, East, South, West

Thanks for any ideas

[ChrisNZ]

Something like this (untested, I may have my tests confused)?

LAT_DIFF = LAT_DEST - LAT_ORIG;

LON_DIFF = LON_DEST - LON_ORIG;

if LAT_DIFF<0 & LON_DIFF<0 then DIRECTION = ifc(abs(LAT_DIFF) > abs(LON_DIFF), 'S', 'E');

if LAT_DIFF>0 & LON_DIFF<0 then DIRECTION = ifc(abs(LAT_DIFF) > abs(LON_DIFF), 'N', 'E');

if LAT_DIFF>0 & LON_DIFF>0 then DIRECTION = ifc(abs(LAT_DIFF) > abs(LON_DIFF), 'N', 'W');

if LAT_DIFF<0 & LON_DIFF>0 then DIRECTION = ifc(abs(LAT_DIFF) > abs(LON_DIFF), 'S', 'W');

[ballardw]

Spherical trigonometry is not my strong point but what is going to be your rules for determining E/W over N/S if the compass angle were to be something like 45 degrees?