The 
Delta Air Linesfleet is one of the largest and most important in the world, and it interestingly operates some of the oldest active commercial aircraft in the United States. It is not the largest airline fleet in the world, as that honor would go to United Airlines. However, the carrier does operate a massive fleet of 990 mainline aircraft, which makes it the second-largest worldwide. The carrier’s massive fleet consists exclusively of aircraft manufactured by US-based Boeing and Europe-based Airbus.