an airline alliance is when two or more airlines make an agreement to work with each other. the three largest airline alliances are star alliance, skyteam, and oneworld. airline alliances make it easier for passengers to travel around the world, reducing their stops or connections. the biggest alliance is star alliance, which has 28 member airlines such as united, lufthansa, and air canada. the second biggest is skyteam, which has 19 members including delta, klm, and air france. the third biggest alliance is oneworld, which has 13 members including american airlines, british airways, and qantas.