Delta's 37 A350s average 5.2 years old, making them its second-youngest widebody equipment, after its 2.9-year-old A330-900s.

US airlines have the world's four largest fleets. Here's how the Boeing and Airbus planes operated by Delta, United, American, and Southwest shape up.

While the big three mainline carriers may seem ... Delta's fleet was made by Boeing.REUTERS/Elijah Nouvelage Delta Air Lines has the oldest plane still flying in the US — a Boeing 757 that ...