United Airlines (UA, Chicago O'Hare) is mulling adding small narrowbody jets to its fleet with potential options including Bombardier Aerospace CSeries, Embraer E2s, as well as B737-7s, Chief Financial Officer Andrew Levy has told FlightGlobal.

The carrier would use these 110-130-seaters to upgauge capacity on routes currently served by regional jets under the United Express brand. However, any changes are pending an agreement with pilots' unions.

United announced in January that it would add a further forty CRJ200s operated under a Capacity Purchase Agreement (CPA) by Air Wisconsin in 2018 to boost the United Express feeder service. The increase is within the scope of a CPA the airlines signed last year, which covers a total of sixty-five CRJ200s, but is only seen as a temporary solution by the airline. The new aircraft will bring the total number of CRJ-200s operated by capacity providers Air Wisconsin and SkyWest Airlines under the United Express brand to 125.

SkyWest, Republic Airlines, Mesa Airlines, GoJet Airlines, and ExpressJet Airlines also operate larger CRJ700, E170, and E175 regional jets under the United Express brand. Under the terms of the current agreement with the pilots, United can only operate up to 255 regional jets seating between 70 and 76 passengers, and it has already reached that number.

Potentially, the carrier can replace the smallest regional jets with larger ones, and the larger regional jets with small mainline aircraft.

According to the ch-aviation fleets module, United mainline's smallest aircraft are currently B737-700s, of which it operates forty. The carrier's narrowbody order book includes thirty-five B737-9s and 100 B737-10 ordered directly from Boeing.

United ordered a further sixty-five B737-700s in 2016 but later converted these aircraft into B737-800s and B737 MAX 9s.