U.S. top carrier, American Airlines (A1G) (AAL) , is bidding farewell to its last 26 McDonnell Douglas MD-80s. The company announced on June 24, 2019, it will retire the aircraft by September 4, 2019, and has published a schedule of the final MD-80 revenue flights.

According to American Airlines’< (A1G) (AAL) /span> announcement, the final revenue flights on its McDonnell Douglas “Mad Dog” aircraft will occur on September 3-4 of this year. The MD-80’s last flight, assigned Flight 80, will depart American’s main base, the Dallas Fort Worth International Airport (DFW) in Texas, for the Chicago O’Hare International Airport (ORD), Illinois, on September 4. The aircraft will then be ferried to Roswell International Air Center (ROW) in New Mexico.

Also known as the Super 80, the MD-80 was the airline’s “workhorse throughout the 1980s and beyond”, American states, calling this a “bittersweet but well-earned retirement” as the U.S. top carrier continues its fleet modernization.

American Airlines (A1G) (AAL) had 30 MD-80 series of aircraft its mainline fleet as of 2018, but currently operates 26 McDonnell Douglas planes. According to planespotters.com data, the airline flies the MD-82 and MD-83 variants, and has previously operated the MD-87. American took delivery of its first MD-80 aircraft in 1983, Boeing’s order and delivery log indicates.

The legacy carrier prides itself for having “the youngest fleet U.S. global network carriers” with an average age of its current mainline fleet being over 10 years. Meanwhile, the average age of the airline’s current “Mad Dog” fleet is over 20 years.

The airline is constantly upgrading its mainline fleet by replacing older aircraft with new models. This must be normal for an airline, which has the largest aircraft fleet in the world: an estimated 957 planes in its mainline fleet, and another 607 aircraft in its regional fleet, taking the total amount of aircraft currently operated by the company to well over 1,500 planes.

In April 2018, American ordered 47 additional Boeing 787-8 and 787-9 Dreamliners to replace its aging 767s and other older wide-bodies. The deliveries of the 787s are scheduled to begin in 2020.

In 2019, the airline also began taking delivery of Airbus A321neo jets. And on June 19, 2019, American placed an order for a total of 50 newly-launched A321 XLR at the Paris Airshow. The deal includes 20 firm orders and 30 conversions of its existing A321neos to the XLR version.

Although the airline’s Super 80 retirement date seems set in stone, the situation of its grounded Boeing 737 MAX planes is quite different. The carrier recently announced it will extend the return to the skies date of its MAX fleet from the previous August 19 deadline to early September. American Airlines (A1G) (AAL) received its first 737 MAX in September 2017.