Which US Carrier Operates The Most Aircraft Types In Its Mainline Fleet In 2026?

The three largest airlines in the world are the three US legacy carriers: American Airlines, Delta Air Lines, and United Airlines. Each is roughly comparable in size and has hubs all across the US, but this doesn't mean that their fleets are even all that similar. All three airlines operate the Airbus A320 family and the Boeing 737, but there are some distinct differences in the overall makeup of their narrowbody fleets. Meanwhile, you see even more variety with the three airlines' long-haul fleets.