Delta's older generation Boeing 737-800s are being retrofitted with the airline's newest first-class seat. The seat debuted with the introduction of the carrier's Airbus A321neo fleet in 2022.

According to data from Cirium, Delta has more than 18,000 flights scheduled on its 737-900ERs this month. In December, almost 3.3 million seats were available only on 737-900ER flights.