United Airlines details December routes for Boeing 767-400ER from Washington Dulles

Despite a limited number of flights between Washington and other destinations next month with the Boeing 767-400ER, the routes are diverse. The aircraft will fly domestically on a short route to Newark (EWR), covering just 213 miles each way.

On the longer end, United's longest domestic route next month with this aircraft is between Dulles and Honolulu International Airport (HNL) in Hawaii. There will be fifteen round trips on this route in December.

"All factors suggest that United is expecting a busy holiday season on its Washington-Honolulu route," evidenced by increased frequency from weekly to daily starting December 19th.

Additionally, United plans to operate its only South American route with the Boeing model next month from Washington Dulles to São Paulo/Guarulhos–Governor André Franco Montoro International Airport (GRU) in Brazil. This route spans over a distance of about 4,736 miles and features overnight flights both ways.

The majority of United’s remaining operations with this plane involve European destinations. Over half of their scheduled flights for December involve transatlantic routes which don't require larger or longer-range aircraft like the Boeing 787 or Boeing 777 but are more demanding than those serviced by smaller planes such as the Boeing 757.

European routes include services to Madrid Barajas Airport (MAD), Rome Fiumicino Airport (FCO), and Humberto Delgado Airport (LIS) in Lisbon. Notably, "United Airlines currently has a monopoly on [the Rome] route," following ITA Airways' temporary suspension until March.

Meanwhile, TAP Air Portugal offers competition on the Lisbon service using Airbus A321LR narrowbody jets against United's larger widebody offering.