Delta says goodbye to the last 'Mad Dogs' flying in the US amid coronavirus retirements

Delta Air Lines will retire its last McDonnell Douglas MD-88s and MD-90s in June, bidding goodbye to two jets that have worn the widget for more than 30 years.

The June timeline comes weeks after the Atlanta-based carrier made known that both aircraft, colloquially known as "Mad Dogs," would depart the fleet this year due to the coronavirus pandemic. Neither jet is due to receive much fanfare for its retirement.

Delta described both the MD-88 and MD-90 as long-standing "workhorses" in its fleet in a statement Thursday. It first flew the MD-88 in 1987 and the MD-90 in 1995.

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Carriers around the world are parking planes as restrictions and fears of COVID-19 keep nearly all would-be travelers on the ground. Trade group Airlines for America (A4A) estimates that U.S. carriers have "idled," or not flown in the past week, 3,003 aircraft as of April 28.

American Airlines, for example, is retiring its 80 Airbus A330-300s, Boeing 757 and 767s, and Embraer E190s as a result of the virus.

Delta is idling around 650 jets, or half of the combined 1,316 planes in its mainline and Delta Connection fleets. While plans remain fluid, it has only finalized the retirements of the MD-88, MD-90 and some Boeing 767 aircraft. It will also temporarily park all of its Airbus A320s and many of its Boeing 737s.

Related: Delta to park A320s, many 737s for length of coronavirus downturn

The MD-88s and MD-90s exit at Delta will mark the first time since the early 1980s that no U.S. carrier is flying a so-called Mad Dog in scheduled passenger service. The family, which included the MD-81, -82, -83, -87, -88 and -90, were at one point or another flown by most domestic carriers, with American Airlines flying as many as 362 aircraft in 2001.

American retired its last MD-80s last September.

The MD-80 family lives on in the form of the Boeing 717 at Delta and Hawaiian Airlines. However, even the future of the 717 is in question as the former carrier is reportedly in discussions to swap the jets for new Boeing 737 MAX.

Delta is scheduled to fly the MD-88s and MD-90s on 23 routes from its Atlanta (ATL) hub in May, according to Cirium schedules.

Related: Delta still flying all of its A220s even as the coronavirus grounds more than half its fleet