United and Delta Have Oldest U.S. Fleets (travelmarketreport.com)

United Airlines has the largest share of planes 25 years or older at 30.7%, followed by Delta at 27.6% and American at 24.3%, while Southwest and Frontier have none. Delta, United and Hawaiian share the oldest average fleet age at 15.0 years, and Delta operates the oldest individual aircraft at 37.4 years. In a survey of over 1,000 travelers, 57% said they care about aircraft age, 71% want airlines to disclose it during booking, and 64% would pay extra to fly a newer plane.