United Airlines (UA, Chicago O'Hare) is reportedly in discussions with Airbus and Boeing about a large order for narrowbody aircraft that would likely be split between the manufacturers, industry sources told Reuters.

None of the parties concerned commented on the report, which said that United could place an order for over 100 B737-8 narrowbodies and possibly "several dozen" larger A321-200neo jets. However, the report did not specify whether the airline was contemplating the standard A321-200NX version or the extended range variants.

United Airlines' previous-generation narrowbody fleet currently comprises eighty-eight A319-100s (19.3 years old on average), ninety-six A320-200s (22.9 years), fifty-three B737-700s (20.8 years), 141 B737-800s (17.3 years), twelve B737-900s (19.8 years), and 136 B737-900(ER)s (8.5 years). It also operates thirty B737-9s and has a further forty B737-8s, forty-nine -9s, and ninety-two B737-10s on firm order from Boeing. It recently increased its MAX order book by 25 units in February 2021. The deliveries of the MAX 8s are scheduled to begin imminently with the first revenue flight planned for July 15, 2021.

The carrier does not operate any A320neo Family aircraft but has fifty A321-200NX(XLR) on firm order from the European manufacturer.

Whilst American Airlines has both B737 MAX and A320neo narrowbodies in the fleet and on order, Delta Air Lines has thus far not ordered any B737 MAX but only A321-200Ns (of which it has 125 on firm order from the manufacturer), the ch-aviation fleets advanced module shows.