Final answer:
The most direct way of flying from one airport to another follows a great circle route, which is the shortest path over the Earth's surface, typically facilitated by the airline infrastructure at each airport.
Step-by-step explanation:
The most direct way of flying from one airport to another is typically described as the route that takes the shortest distance between the two points. This is often referred to as 'as the crow flies', which implies a straight line flight over any obstacle. However, flights do not actually follow a straight line over the globe but rather a path known as a great circle route. This route represents the shortest distance between two points on the surface of a sphere, such as Earth.
When calculating travel distances and times between airports, factors such as the proximity of the airport to the intended destination, the development of civil airline infrastructure at the origin and destination, and the curvature of the Earth are taken into account. For example, to calculate the distance and travel time by plane from the Albuquerque International Airport in New Mexico or the San Francisco International Airport in California to various cities around the world, one would use tools and formulas specific to aviation and geography.