Point-to-Point

• Some airlines plan their flight routes using point-to-point models, based only on flights traveling to and from a city. These routes are only planned between the two cities, with no connecting flights to get to a third destination.
  
  

Hub-and-Spoke

• The hub-and-spoke model allows airlines to maximize the number of passengers they serve by offering connections to domestic and international locations. This model is more complex, leading to lower usage of flight capacity and a higher wait time for them, which increases costs. However, this model also offers more routes and is ultimately more profitable for an airline if implemented successfully.
  
  

Air Traffic Control

• Airlines also depend on air traffic controllers to make sure their planes don't collide with others. Although airlines plan their own routes, air traffic controllers are in charge of making sure planes take off and land at safely without interfering with other each en route to their destinations. Air traffic will guide each specific flight and determine the route it takes for any particular flight although the departure and destination cities are determined by the airlines.