With a fleet size of over 950 aircraft, American Airlines is currently the largest airline in the world. The airline operates both domestic and international flights and serves over 50 countries worldwide.

As of early 2026, United Airlines holds the title for the world's largest mainline fleet, operating approximately 1,058 aircraft. They are closely followed by American Airlines, which operates around 1,013 mainline planes. It is important to distinguish between "mainline" fleets and "regional" partners; if you include regional subsidiaries, American Airlines often edges out ahead in total aircraft under their corporate umbrella. However, in terms of sheer ownership by a single entity, the largest "owners" of aircraft are actually aircraft leasing companies rather than airlines. Companies like AerCap own significantly more planes than any individual airline (over 1,700 aircraft), which they then lease out to carriers all over the world. Among the commercial airlines, the "Big Three" U.S. carriers—United, American, and Delta—consistently dominate the rankings for the largest operational fleets globally.