Airline alliances may also create disadvantages for the traveller, such as higher prices when competition is erased on a certain route or less frequent flights; for instance, if two airlines separately fly three and two times a day respectively on a shared route, their alliance might fly less than 5 (3+2) times a day on the same route. This might be especially true between hub cities for each airline. e.g., flights between Detroit Metropolitan Wayne County Airport (a Delta Air Lines fortress hub) and Amsterdam Airport Schiphol (a KLM fortress hub).[9][10][11]