When you're flying to many cities, one of the recurring problems is to determine either the shortest path between two cities or the shortest time of travel. From the viewpoint of the airline traveler, the aim is to find the shortest set of flights between two cities. From the viewpoint of the airline, determining how to route their passengers between cities as efficiently as possible increases customer satisfaction and lowers prices (less fuel, wear and tear on equipment, ease for the flight crew, and so on). Within the context of GraphFrames and graph algorithms, one approach would be to use the breadth first search (BFS) algorithm to help us find the shortest path between these airports.