How to find distance between two points using latitude and longitude

Question

I have a ROUTES table which has columns SOURCE_AIRPORT and DESTINATION_AIRPORT and describes a particular route that an airplane would take to get from one to the other.

Answer 1

There is a formula called great circle distance to calculate distance between two points. You probably can load is as a library for your operating system. Forget the haversine, our planet is not a perfect sphere. If you use this value often, save it in your routes table.